8. The Seven Sins: Vices or Virtues?

The Seven Sins: Vices or Virtues?

PEOPLE LOVE TO COMPLAIN about their memories. When I meet someone for the first time and the conversation turns to my research, I know
what's coming next. "You should study me;' my new acquaintance will almost invariably say with a shrug, especially if he or she is over age forty.
Then follows a list of exasperating recent encounters with absent-mindedness or name blocking, and finally a sigh of relief when I offer assurances
that these kinds of memory problems are common. The very pervasiveness
of memory's imperfections, amply illustrated in the preceding pages, can
easily lead to the conclusion that Mother Nature committed colossal blunders in burdening us with such a dysfunctional system. John Anderson, a
cognitive psychologist at Carnegie-Mellon University, summarizes the prevailing perception that memory's sins reflect poorly on its design: "over the
years we have participated in many talks with artificial intelligence researchers about the prospects of using human models to guide the development of artificial intelligence programs. Invariably, the remark is made,

'Well, of course, we would not want our system to have something so unreliable as human memory:"

It is tempting to agree with this characterization, especially if you've
just wasted valuable time looking for misplaced keys, read the statistics on
wrongful imprisonment resulting from eyewitness misidentification, or
woken up in the middle of the night persistently recalling a slip-up at work.
But along with Anderson, I believe that this view is misguided: it is a mistake to conceive of the seven sins as design flaws that expose memory as a
fundamentally defective system. To the contrary, I suggest that the seven
sins are by-products of otherwise adaptive features of memory, a price we
pay for processes and functions that serve us well in many respects.

To support this suggestion, I'll draw on evidence and ideas from a variety of sources, including evolutionary biology and psychology. Evolutionary psychology has sparked heated debates recently. Proponents of this
approach draw heavily on Darwin's ideas about natural selection in an attempt to explain cognition and behavior, claiming that the mind cannot be
understood fully without adopting an evolutionary perspective. They contend that the mind consists of a collection of specialized abilities that arose
to solve specific problems posed by the environment during the course of
evolution, and that natural selection is the primary mechanism responsible
for the mind's complex design. Evolutionary theorists contend further that
much of the mind's structure is specified innately by intricate genetic programs. From this perspective, the task of psychology is to engage in what
the cognitive psychologist and evolutionary theorist Steven Pinker calls
"reverse-engineering" :

In forward-engineering, one designs a machine to do something; in reverse-engineering, one figures out what a machine was designed to do.
Reverse-engineering is what the boffins at Sony do when a new product is announced by Panasonic, or vice versa. They buy one, bring it
back to the lab, take a screwdriver to it, and try to figure out what all the parts are for and how they combine to make the device work.

Critics of the evolutionary approach, in contrast, express concern
about several aspects of evolutionary theorizing. For example, they worry
that evolutionary ideas too often rely on large doses of speculation - and
too little on hard data. They question whether evolutionary theories can be
adequately tested in a way that allows us to understand the origins of a particular ability, or whether attempts at reverse-engineering have succeeded.
Some critics contend that evolutionary psychologists assign too much
weight to innate genetic programs when attempting to explain the mind's
abilities and complexities; others believe that the mind is better viewed as a
general-purpose problem solver than as a collection of specialized abilities.
And some critics wonder whether an evolutionary perspective really adds
anything to the nonevolutionary theories that psychologists construct in
their attempts to understand the working of the mind.

I'll return to some of these issues later in the chapter. Though I share
the critics' concerns regarding the testability of evolutionary claims, I've
drawn on evolutionary perspectives in earlier work, and have found that an
evolutionary orientation can serve as a rich source of suggestions and hypotheses. In previous chapters of this book, I focused on lessons that experimental research has taught us about each of the seven sins. In this chapter,
the spirit is more exploratory; I advance ideas about the origins of the
seven sins which can help us to place them in a broader perspective, think
thoughts that we might nOt otherwise consider, and appreciate why memory's vices can also be its virtues.

WHEN LESS IS MORE.

To illustrate the general thrust of my proposal, consider what Marc Hauser,
the Harvard evolutionary psychologist who studies animal behavior, calls
"intelligent errors." In his review of studies concerning spatial navigation in
various species, Hauser observes that animals sometimes make seemingly
bizarre mistakes when they navigate their environments. For instance, train
a rat to navigate a maze to find a food reward at the end, and then place a
pile of food halfway into the maze. The rat will run right past the pile of
food as if it did not exist, continuing to the end, where it seeks its just reward!

Why not stop at the halfway point and enjoy the reward then?
Hauser suggests that the rat is operating in this situation on the basis of
"dead reckoning" a method of navigating in which the animal keeps a
literal record of where it has gone by constantly updating the speed, distance, and direction it has traveled. A similarly comical error occurs when a
pup is taken from a gerbil nest containing several other pups and is placed
in a nearby cup. The mother searches for her lost baby, and while she is
away, the nest is displaced a short distance. When the mother and lost pup
return, she uses dead reckoning to head straight for the nest's old location.
Ignoring the screams and smells of the other pups just a short distance
away, she searches for them at the old location. Hauser contends that the
mother is driven by signals from her spatial system.

Though the behaviors in these examples seem perverse, they reflect
reliance on a type of navigation that serves the animals quite well in most
situations. The system is adapted to aspects of the animal's environment,
but can get the animal into trouble when things change in unexpected
ways. Fortunately, nests don't move in the real world that the animal inhabits; such confusing changes require the intervention of a cunning experimenter and tend not to occur in the wild.

Something similar occurs in the behavior known as imprinting. After
hatching, a baby chick treats the first moving object she encounters as her
mother. Because the first moving object that a chick encounters almost always is the mother hen, imprinting is an effective mechanism for ensuring
that a newborn chick follows its mother in order to receive proper feeding and care. But as shown by the student of animal behavior Konrad Lorenz,
when a baby chick first sees another moving object after hatching - a rolling red ball or a human (Lorenz used himself) - the animal imprints on
the object and follows along as it would normally follow the mother hen.
Consequently, a small flock of goslings often followed Lorenz. Imprinting
depends on a specialized memory mechanism that is adapted to the regularities of the chick's ordinary environment. Though usually adaptive, imprinting can cause problems for the chick if the mother is not the first
moving object that the bird encounters. But in nature, this event is highly
improbable.

I believe something similar is going on with memory's seven sins:
mechanisms that serve us well much of the time occasionally get us into
trouble. Of all the sins, seeing the positive side of persistence is perhaps easiest. Rene Descartes crystallized the issue several centuries ago. "The utility
of all the passions consists in their strengthening thoughts which it is good
that [the soul] preserve:' he observed. "So too all the evil they can cause
consists either in their strengthening and preserving those thoughts more
than necessary or in their strengthening and preserving others it is not
good to dwell upon." Although intrusive recollections of trauma can be
disabling, it is critically important that emotionally arousing experiences,
which sometimes occur in response to life-threatening dangers, persist over
time. The amygdala and related structures contribute to the persistence of
such experiences by modulating memory formation, sometimes resulting
in memories we wish we could forget. But this system boosts the likelihood
that we will recall easily and quickly information about threatening or
traumatic events whose recollection may one day be crucial for survival.
Remembering life-threatening events persistently - where the incident
occurred, who or what was responsible for it - boosts our chances of
avoiding future recurrences.

Transience, forgetting over time - also has an adaptive side. Forgetting can be frustrating, but it is often useful and even necessary to dismiss information that is no longer current, such as old phone numbers or
where we parked the car yesterday. As the psychologists Robert and Elizabeth Bjork have pointed out, information that is unimportant or no longer
needed will tend not to be retrieved and rehearsed, thereby losing out on
the strengthening effects of post-event retrieval and becoming gradually
less accessible over time.

John Anderson and his associates have taken this line of thinking even
further, arguing that forgetting over time reflects an optimal adaptation to
the structure of the environment. Anderson examined various situations
involving information retrieval and analyzed how the past history of using
a particular bit of information predicts its current use. He observed a regularity that parallels the form of transience in human memory: the demand
for a particular piece of information drops as greater periods of time pass
since its last use. For example, the Anderson group has noted that in library
systems, books that have been checked out recently or frequently in the past
are more likely to be requested at a specific present moment than books
that have been checked less recently or frequently. They observed something similar when they examined headlines in the New York Times for 730
days in 1986 and 1987, recording each time a particular word appeared. The
likelihood that a particular word would appear on a specific day fell as a
function of the time since it was last used. Anderson's group has found
similar parallels in other situations, including the use of words in conversations with children, and the likelihood of receiving an e-mail message from
a correspondent as a function of the time elapsed since earlier messages.

A system that renders information less accessible over time is therefore highly functional, because when information has not been used for
longer and longer periods of time, it becomes less and less likely that it will
be needed in the future. On balance, the system would be better off setting
aside such information - and transience leads to exactly that outcome.
Anderson suggests that the general form of forgetting documented in numerous experiments - the rate of forgetting slows down over time - reflects a similar function in the environment which relates past and present
use of information. According to Anderson, our memory systems have
picked up on this regularity, and in essence make a bet that when we
haven't used information recently, we probably won't need it in the future.
We win the bet more often than we lose it, but we are acutely aware of the
losses - the frustrations of forgetting - and are never aware of the wins.

The basic idea here resembles what scientists who study animal behavior in natural environments call a "trade-off." Think about a squirrel
that gingerly approaches a fractured cookie near a group of picnickers. The
squirrel bravely grabs a bit of the cookie and retreats to a nearby tree before
eating it. It returns several times and, on each occasion, grabs a cookie fragment, brings it back to the tree, and devours it. Though not the most efficient way to consume a cookie, this procedure allows the squirrel to re duce its exposure to possible predators. Researchers have indeed found that
squirrels are more likely to haul small pieces of cookie to cover than big
ones - big pieces take longer to eat than small ones, and thus place the
squirrel at greater risk. There is a trade-off between maximizing the benefits of feeding and minimizing the costs of encountering a predator; the
squirrel's behavior suggests that it is balancing the two. Similarly, in memory there is a trade-off between the benefit of reducing the accessibility of
information that hasn't been used recently or frequently, which probably
won't be needed in the future, and the annoyance or other costs of forgetting.

Some of the same ideas involving frequency and recency of usage also
apply to blocking in semantic memory, as seen most clearly in tip-of-thetongue states. Recall that people are most susceptible to blocking on names
and other bits of information that have not been used recently. Recall also
that blocking often results from a weakened connection between conceptual representations (things you know about a person or object) and
phonological representations (the sound of a word or name). Tip-of-thetongue states may thus reflect the principle articulated by Anderson's
group: information that has not been used recently begins to lose out
in memory because the odds are growing that it will not be needed. When
a connection between conceptual and phonological representations has
not been strengthened recently by using a word or a name, the link becomes ever more unreliable and we become correspondingly susceptible to
blocking.

Some types of blocking reflect the operation of inhibitory processes
that render information inaccessible (see Chapter 3). Psychologists and
neuroscientists have long recognized that inhibition is a fundamental feature of the nervous system: the brain relies on mechanisms that reduce activity as much as mechanisms that intensify it. Think about what might result without the operation of inhibition: a memory system in which all
information that is potentially relevant to a cue invariably and rapidly
springs to mind. Consider the following experiment. Try to recall an episode from your life that involves a table. What do you remember, and how
long did it take to come up with the memory? You probably had little difficulty coming up with a specific incident - perhaps a conversation at the
dinner table last night, or a discussion at a conference table at the office this
morning. Now imagine that the cue "table" brought forth all the memories
that you have stored away involving a table. There are probably hundreds
or thousands of such incidents. What if they all sprung to mind within seconds of considering the cue? A system that operated in this manner would
likely result in mass confusion produced by an incessant coming to mind of
numerous competing traces. It would be a bit like using an Internet search
engine, typing in a word that has many matches in a worldwide data base,
and then sorting through the thousands of entries that the query elicits. We
wouldn't want a memory system that produces this kind of data overload.
Robert and Elizabeth Bjork have argued persuasively that the operation of
inhibitory processes helps to protect us from such potential chaos.

The basic idea underlying the foregoing analyses of transience and
blocking is that as far as memory is concerned, less is sometimes more.
That same principle applies equally - if not more strongly - to absentmindedness. Absent-minded errors occur in part because establishing a
rich memory representation that can later be recollected voluntarily requires attentive, elaborate encoding. Events that receive minimal attention
and elaboration as they are occurring also stand little chance of being recollected subsequently. But what if all events were registered in elaborate detail, regardless of the level or type of processing to which they were subjected? The result would be a potentially overwhelming clutter of useless
details, as happened in the famous case of the mnemonist Shereshevski.
Described by the Russian neuropsychologist Alexander Luria, who studied
him for years, Shereshevski formed and retained highly detailed memories
of virtually everything that happened to him - both the important and
the trivial. Yet he was unable to function at an abstract level because he was
inundated with unimportant details of his experiences - details that are
best denied entry to the system in the first place. An elaboration-dependent system ensures that only those events that are important enough to
warrant extensive encoding have a high likelihood of subsequent recollection. Events that do not attract attention and elaboration are likely to be
less important and, hence, less likely to be needed for recall at a later time.

An elaboration-dependent system allows us to enjoy the considerable
benefits of operating on automatic pilot, without having memory cluttered
by unnecessary information about routine activities. As I discussed in
Chapter 2, tasks that initially require considerable attention and effort,
such as learning to drive a car, are eventually handled by automatic processes after sufficient practice, thereby freeing up resources for more im portant matters. It is surely infuriating when, operating on automatic pilot,
you put down a book or your wallet in an atypical location and later can't
remember where you left it. But suppose that when you misplaced the object, you were mentally absorbed in thinking about ways to cut costs in
your business, and came up with a great idea that saved you lots of money.
Operating on automatic led to an irritating incident of absent-minded forgetting, but because you were focusing attention on your business, you
gained a lasting benefit. When we can perform routine tasks by relying on
automatic processes, we are free to devote attention to more consequential
matters. Because we rely on automatic processes frequently in our daily
lives, the occasional absent-minded error seems a relatively small cost for
such a large benefit.

The "less is more" principle also applies to two of the sins involving
memory distortion: misattribution and suggestibility. I showed earlier that
many instances of misattribution and suggestibility reflect poor memory
for the source of an experience (see Chapters 4 and 5). When we don't recall
exactly who told us a particular fact, where we saw a familiar face, or
whether we actually witnessed an event or only heard about it later, the
seeds of memory distortion are sown. If we don't recall the exact source of
an experience - either because the details were not initially well encoded,
or because they fade over time - we become quite vulnerable to the misattributions considered in Chapter 4 which are associated with source confusions and cryptomnesia (unintentional plagiarism). We may also be vulnerable to incorporating suggestions made after an event regarding the
nature of specific details that we remember only vaguely. Accepting inaccurate suggestions can have grave consequences for eyewitness testimony, as I
showed in Chapter 5.

But what would be the consequences and costs of retaining the myriad of contextual details that define our numerous daily experiences? Assume, as I've argued, that memory is adapted to retain information that is
most likely to be needed in the environment in which it operates. We seldom need to remember all the precise sensory and contextual details of our
every experience. Would an adapted system routinely record all such details
as a default option, or would it carefully record such details only when circumstances warn that they may later be needed? Our memories operate on
the latter principle, and most of the time we are better off for it. We pay the
price, however, when we are required to recollect detailed source informa, 92 tion about an experience that did not elicit any special effort to encode
source details.

Some types of misattribution occur when we fail to recollect specific details of an experience, and at the same time recall the general sense
of what happened. In laboratory demonstrations of false recognition considered in Chapter 4, for instance, people incorrectly claimed that they previously heard the word sweet when in fact they had heard a group of semantically associated words, including candy, sugar, and taste. In related
experimental procedures, people claim to have seen a picture of a particular car or teapot earlier in the experiment, when they had actually seen pictures of physically similar but not identical cars and teapots. Misattribution
occurs because participants in these experiments respond on the basis of
memory for the general sense or gist of what they saw or heard.

However, the ability to remember the gist of what happened is also
one of memory's strengths: we can benefit from an experience even when
we do not recall all of its particulars. Indeed, studies conducted in my laboratory show that misattributions that result from remembering the gist are
signs of a healthy memory system. For instance, after studying semantically
associated words such as candy, sugar, and so forth, patients with amnesia
caused by damage to the hippocampus and nearby structures in the temporallobe remembered fewer of these words than did healthy control subjects - hardly a surprising result. But the amnesic patients were also less
likely than the controls to make the mistake of falsely recognizing semantically related words such as sweet, which had not been presented in the originallist. The same thing happened when amnesic patients studied pictures
of cars, teapots, and other objects: compared to healthy controls, they later
recognized fewer of the pictures they actually saw but were also less likely
to falsely recognize similar pictures they hadn't seen earlier. Temporal
lobe damage impaired patients' memories for both the particulars and
the gist of what they had experienced, resulting in reduced true and false
memories.

Memory for gist information is fundamental to such abilities as categorization and comprehension, allowing us to generalize across and organize our experiences. To develop a coherent category of "birds;' for example, it's important to learn that a cardinal and an oriole are both members
of the category despite superficial differences in their appearances. We need
to notice and retain the recurring features that unite all birds, and to ignore
the idiosyncratic details that differentiate among them. The cognitive psychologist James McClelland has developed a theoretical model in which
generalization results from retaining the gist of prior experiences. McClelland contends that generalization "is central to our ability to act intelligently:' Yet in his model McClelland also notes that "such generalization
gives rise to distortions as an inherent by-product."

This idea receives striking experimental support from a recent study
of false recognition in adults with a type of autistic disorder. Autism is associated with poor social skills, impaired communication abilities, and a
highly rigid, literal style of processing information. But autistic children
and adults can also show surprisingly good, and sometimes spectacular,
rote memory abilities, as illustrated some years ago by Dustin Hoffman's
character in the popular movie Rain Man. Despite his many limitations,
Raymond Babbitt was a repository of obscure facts, spewing forth such
nuggets as the name of the only major airline never to have suffered a crash
(Qantas).

Scientists have described autistic patients who show exceptional
memory for dates, names, or visual patterns. The neurologist David Beversdorf and his collaborators presented lists of semantically associated
words to autistic adults and to a nonautistic control group. On a later test,
the autistic subjects recognized just as many of the words they had studied
earlier as nonautistic subjects did. But the autistic group had fewer false
alarms than the non autistic group to semantically related words that they
hadn't studied earlier. The autistic group thus more accurately discriminated between true and false memories than cognitively intact subjects.

This pattern contrasts with that of the amnesic patients who showed
reduced true memories and reduced false memories. The autistic adults
were less likely than controls to generalize from the words on the study list.
They retained individual memories of the specific words they had studied,
but not the semantic gist that misleads cognitively normal adults down the
path of false recognition. A memory system that is not susceptible to gistdriven false recognition might free us from occasional bouts of misattribution. But it could also turn us into something like Raymond in Rain
Man, burdened by a rote record of trivial facts while remaining insensitive
to patterns and regularities in the environment which our memory systems
normally exploit to our benefit. False recognition is, in part, a price we may
pay for the benefit of generalization.

The sin of bias is also partly attributable to important strengths of our
cognitive systems. Stereotypical biases often lead to unwarranted evaluations of individuals based on accumulated past experiences with groups, as
we saw in Chapter 6. Though stereotypes can produce these undesirable
consequences, they also make our cognitive lives more manageable by promoting generalizations that, on average, are reasonably accurate. The social
psychologist Gordon Allport dearly saw this point back in the 1950S. He
characterized stereotypes as consequences of ordinary processes of perception and memory, "Iman's] normal and natural tendency to form generalizations, concepts, categories, whose content represents an oversimplification of his world of experience." Stereotypical biases constitute another
price we pay for memory processes that generalize across past experiences.

We also saw that bias often results in memories that depict the self in
an overly favorable light. Egocentric biases lead us to remember better
grades than we actually achieved, or to exaggerate in memory our contributions at work or at home. Consistency and change biases can help to justify our involvement in a relationship, and hindsight biases make us seem
wiser in retrospect than we actually were. On the face of it, these biases
would appear to loosen our grasp on reality and thus represent a worrisome, even dangerous tendency. After all, good mental health is usuallyassociated with accurate perceptions of reality, whereas mental disorders and
madness are associated with distorted perceptions of reality. But as the social psychologist Shelley Taylor has argued in her work on "positive illusions;' overly optimistic views of the self appear to promote mental health
rather than undermine it. Far from functioning in an impaired or suboptimal manner, people who are most susceptible to positive illusions generally
do well in many aspects of their lives. Depressed patients, in contrast, tend
to lack the positive illusions that are characteristic of nondepressed individuals. Remembering the past in an overly positive manner may encourage us to meet new challenges by promoting an overly optimistic view of
the future, whereas remembering the past more accurately or negatively
can leave us discouraged. Clearly there must be limits to such effects, because wildly distorted optimistic biases would eventually lead to trouble.
But as Taylor points out, positive illusions are generally mild and are important contributors to our sense of well-being. To the extent that memory
bias promotes satisfaction with our lives, it can be considered an adaptive
component of the cognitive system.

SEEKING THE SOURCES OF THE SEVEN SINS.

Up to now, I've used the word adaptive in a quite general sense, but to
explain the possible sources of the seven sins I need to clarify what I mean
when I say that a feature of memory is adaptive. Psychologists use the term
adaptation in at least two ways. One usage comes from evolutionary theory
and has a highly specific, technical meaning. An adaptation in this sense is
a feature of a species that came into existence through the operation of natural selection because it increased the reproductive fitness of individuals.
Darwin's argument for natural selection as the sole evolutionary mechanism to account for adaptive design rested on three fundamental observations. First, he observed that only a portion of each generation manages to
reproduce. Second, he noted that offspring are not identical to their parents
- some are taller, faster, or stronger than others. Variations like these that
can be passed on to subsequent generations are considered heritable. Third,
Darwin argued that some aspects of heritable variation raise the likelihood
that their bearers will survive and reproduce. Features of an organism that
result from natural selection are adaptations.

However, psychologists often use the term "adaptation" in a looser
manner - a colloquialism that refers to a feature of an organism that has
generally beneficial consequences, whether or not it arose directly in response to natural selection during the course of evolution. Within the domain of memory, for instance, recalling telephone numbers and learning to
use a computer provide examples of this looser sense of an adaptive feature. We can remember frequently used telephone numbers reasonably
well, and in that sense memory can be considered adapted to the task. But
telephones are such a recent invention that this ability could not have
arisen during the course of evolution as an adaptation produced by natural
selection. The same goes for the abilities needed to learn to use a computer
or any other type of modem technology: our memory systems allow us to
accomplish these tasks, but memory cannot have arisen as an adaptation
for learning to operate modern technology.

The Harvard paleontologist Stephen Jay Gould has used the term
exaptation to refer to "features that now enhance fitness, but were not built
by natural selection for their current role." Exaptations are, in effect, adaptations that are co-opted to perform functions other than the one for which
they were originally selected. For instance, evolutionary biologists believe
that the feathers of birds likely evolved initially as adaptations to perform
such functions as thermal regulation or capturing prey, and were only later
co-opted for the entirely different function of flight. In human cognition,
the ability to read is an example of an exaptation. Because significant portions of the population have begun to read only during the past few centuries, reading is too new to be a product of natural selection. But reading
draws on basic visual and cognitive abilities that likely arose as adaptations.
Similarly, our abilities to remember telephone numbers and to use computers are not themselves evolutionary adaptations, but draw on features of
memory that presumably originated as adaptations.

Gould and his Harvard colleague Richard Lewontin delineated a third
type of evolutionary development called a "spandrel" - a special type of
exaptation that is an unintended consequence or by-product of a particular
feature. Whereas the exaptations discussed previously originated as adaptations, and were later hijacked to perform a different function, spandrels
have no adaptive function from the outset. The term spandrel is used in architecture to designate the leftover spaces between structural elements in a
building. As an example, Gould and Lewontin described the four spandrels
in the central dome of Venice's Cathedral of San Marco: spaces between
arches and walls that were subsequently decorated with four evangelists
and four biblical rivers. The spandrels were not designed for the specific
purpose of housing these paintings, although they do so quite well. Similarly, people seeking shelter can sleep in the spaces between pillars of a
bridge, even though the pillars and spaces were not put there in order to
provide shelter.

Determining whether particular features of the human mind are adaptations, exaptations, or spandrels is a difficult task that has turned into a
kind of blood sport in contemporary psychology and biology. Evolutionary
psychologists have sought to explain human cognition and behavior in
terms of adaptations preserved by natural selection. "The mind is a system
of organs of computation, designed by natural selection to solve the kinds
of problems our ancestors faced in their foraging way of life," contends Steven Pinker, an enthusiastic advocate of the evolutionary perspective. The
psychologist Leda Cosmides and the anthropologist John Tooby, pioneers
of evolutionary psychology, argue in a similar spirit. "The human mind
consists of a set of evolved information-processing mechanisms in the human nervous system;' they assert. "These mechanisms, and the developmental programs that produce them, are adaptations, produced by natural
selection over evolutionary time in ancestral environments."

In contrast, critics of evolutionary psychologists, including Stephen
Jay Gould, maintain that it is too easy to come up with after-the-fact explanations of mind and behavior that appeal to adaptations and natural selection - what have come to be known as "just so" stories. Gould holds that
many current features of the human mind are exaptations and spandrels
- in addition to reading, other examples include writing and religious beliefs. He argues that exaptations and spandrels are such dominant influences in shaping the contemporary human mind that they constitute "a
mountain to the adaptive molehill." Debates between advocates of these
contrasting perspectives, exemplified by a 1997 exchange in the New York
Review of Books between Pinker and Gould, are often quite contentious.

For evolutionary accounts of mind in general and memory in particular to amount to more than speculative exercises in post hoc storytelling,
debates about the relative importance of adaptations, exaptations, and
spandrels will have to be settled by empirical tests of hypotheses and predictions generated by alternative positions. Experimental psychologists
such as myself tend to require hard evidence from controlled studies to decide between competing hypotheses. Although we do not have direct access
to the evolutionary record of human cognition - there were no psychologists recording observations of our ancestors' behaviors in ancient environments - that doesn't preclude rigorous testing of evolutionary hypotheses.

The University of Texas psychologist David Buss and his associates
have recently provided a helpful discussion of how such testing might proceed. They provide thirty examples in which predictions from an evolutionary perspective anchored by ideas of adaptation and natural selection
led to empirical discoveries about human behavior or cognition. The cited
examples include the nature of male sexual jealousy, patterns of spousal
and same-sex homicide, relationship-specific sensitivity to betrayal, and
mate guarding as a function of female reproductive value.

To test for evolutionary adaptations, psychologists and biologists rely
on several types of evidence and considerations. One criterion is that of
complex or special design: a feature of an organism is likely to be an adaptation if its internal structure is so complex as to minimize the possibility
that the feature arose by chance or as an incidental by-product of something else. The vertebrate eye is a classic example of complex design. Intricate interdependencies among its many parts make it highly likely that the
eye was designed by natural selection to accomplish the task of seeing, and
highly unlikely that it developed by chance or as an incidental by-product.
In the early nineteenth century, the theologian William Paley argued that
such complex design reflects the presence of a designer with foresight. Invoking a comparison with a watchmaker, Paley noted that the intricate
structure of a watch, like that of a living organism, reveals the presence of
design that is devoted to specific functions, and cannot be attributed to a
fortuitous alignment of all the different parts in just the right arrangement.
In his book The Blind Watchmaker, the biologist Richard Dawkins offered a
Darwinian twist on Paley's watchmaker argument. A true watchmaker sets
out with the goal of designing a watch, Dawkins observed, but natural selection is blind - it has no goal, purpose, or foresight.

Adaptations lead to differential reproductive success. It therefore follows that if a specific trait or feature has been favored by selection, it should
be possible to find some evidence in the numbers of offspring produced by
the trait's bearers. For instance, the hypothesis that women prefer to mate
with tall men recently received support from the finding that tall men bear
more offspring than short men. Physical stature in men may thus be, in
part, an adaptation produced by selection.

The operation of natural selection may also be indicated when a trait
turns up consistently in different species. Consider, for instance, the case of
bodily symmetry. Humans and other organisms vary in the degree to
which their bodies deviate from perfect left-right symmetry. In studies
where raters judge attractiveness, greater bodily symmetry is generally associated with higher ratings. Further, symmetry produces advantages in
sexual competition over asymmetry across a wide variety of nonhuman
species, including insects, birds, and primates. Biologists have found that
asymmetry is associated with the existence of genetic abnormalities and
with exposure to negative environmental events, such as parasites and pollutants. Combining these observations with the sheer pervasiveness of selection for individuals with high symmetry across different species, there
are grounds for arguing that bodily symmetry is an adaptation produced
by natural selection. Though this idea is not accepted by all researchers - a
controversy exists concerning how symmetry and asymmetry come about
- the findings point toward the operation of selective pressures.

An adaptation may also be signaled by the presence of what anthropologists call human universals: traits that are present in all recorded human cultures. For example, cross-cultural studies indicate that physical attractiveness is widely valued by both men and women (although more by
men) and that people from different cultures tend to agree in their judgments of facial attractiveness. Aspects of facial attractiveness have, in turn,
been associated with greater physical and mental health, raising the possibility that it may be an evolutionary adaptation.

The fact that a feature is a universal does not necessarily indicate that
it arose as an adaptation. The anthropologists Donald Brown and Steven
Gaulin each point out that universals can also arise from cultural traits that
are ancient and highly useful, and therefore have spread through many societies. For example, the use of fire (particularly for cooking) is a human
universal. However, we do not need to postulate that the use of fire reflects
the operation of a shared adaptation. It's simpler to argue, as both Brown
and Gaulin do, that people have long been exposed to fire and recognize its
usefulness. But as Gaulin points out, if this type of cultural explanation can
be ruled out, then the remaining universals can help to guide the search for
psychological adaptations.

Conversely, if a trait is universally present across cultures with a single
exception, that exception does not necessarily rule out the existence of an
adaptation; there could be other cultural factors operating that help to explain the exception. On balance, then, while universals do not provide
definitive evidence for (or against) adaptations, they can serve as helpful
guideposts.

How about memory and the seven sins? Though we don't have a great
deal of evidence on which to base strong claims about evolutionary origins,
some relevant data come from studies of gender differences. Consider one
evolutionary hypothesis about memory noted in the article by Buss and coworkers: women have more accurate memories for the spatial locations
of objects than men do. The Canadian psychologists Marion Eals and
Irwin Silverman noted that archeological and paleontological data from
the hunter-gatherer period, one of the important epochs when human cognition evolved, suggest that men engaged primarily in hunting whereas
women primarily foraged. Eals and Silverman hypothesized that these different activities placed different demands on spatial cognition and memory. Specifically, they suggested that successful foragers must locate food
sources that are embedded within complex arrays of vegetation, and remember those locations for later visits. Natural selection therefore should
have favored the development of superior memory for the spatial location
of objects in women compared to men.

Eals and Silverman tested this hypothesis by showing men and women
spatial arrays of objects. In one experiment, the objects appeared in a drawing; in another, they were dispersed on desks and tables in a room. In both
experiments, women remembered the locations of objects more accurately
than did men. But men outperformed women on other spatial tasks that,
according to Eals and Silverman, tap spatial abilities that would have been
required for successful hunting.

Some subsequent studies have replicated Eals and Silverman's results,
whereas others have placed various qualifications and limitations on the
findings. The question of whether spatial memory abilities in women are
adaptations produced by selection for foraging skills is, accordingly, not yet
settled. Nonetheless, these studies provide an example of how evolutionary
hypotheses about the origins of memory can be formulated and tested.

A related type of evidence hinting at selection for sex differences in
spatial memory abilities comes from research by the psychologist David
Sherry at the University of Western Ontario, who has studied memory in
various bird species, including brown-headed cowbirds. When they breed,
female cowbirds lay a single egg in another species' nest, and then spend the
rest of the day searching for other nests in which they can lay eggs during
the coming days. Females must remember the location of the nests, as the
males do not help the females to locate nests (in other cowbird species,
both sexes playa role in such nest hunting).

In earlier studies, Sherry and others had demonstrated that the avian
hippocampus plays a key role in allowing food-storing birds to remember
where they have hidden food. A Clark's nutcracker, for instance, stores as
many as thirty thousand seeds in five thousand locations during the fall, retrieving them the next spring. The bird accomplishes this daunting recall
task with great success. Overall, the hippocampus is consistently larger in
species that store and retrieve food than in those that do not. Further, after
damage to the hippocampus, food-storing birds have great difficulty remembering the locations of their food caches.

If the avian hippocampus is important for spatial memory, Sherry
reasoned, then female brown-headed cowbirds ought to have a relatively
larger hippocampus than male brown-headed cowbirds as a consequence
of selection for spatial ability in the females related to finding and remembering nest locations. Measurements of hippocampal volume in relation to
the overall size of cowbirds' brains revealed exactly that: the hippocampus
is indeed relatively larger in females than males. No such sex differences
were found in two closely related species of birds that do not lay eggs in
other birds' nests.

Studies of spatial abilities in other species show that the direction of
sex differences can be reversed when selection pressures favor the development of spatial learning in males. Steven Gaulin at the University of Pittsburgh examined two types of male rodents: a polygamous meadow vole
that expands its home range during breeding season to increase mating opportunities, and a monogamous prairie vole that does not. Expanding its
home range should produce selection for spatial abilities in the polygamous meadow vole. When Gaulin tested the two types of voles in laboratory maze learning tasks, he found evidence for superior spatial abilities in
male compared with female meadow voles, and no sex difference among
prairie voles. The hippocampus was also larger in male than female
meadow voles, but no difference existed in hippocampal size between male
and female prairie voles.

The work of Gaulin, Sherry, and their associates strongly supports the
general idea that some features of memory are adaptations produced by
natural selection. I'm not aware of any comparable evidence that speaks directly to the origins of the seven sins. Back in the 1980s, David Sherry and I
coauthored a theoretical article arguing that some features of memory are
adaptations produced by selection whereas others are exaptations; we tried
to identify characteristics of each. I take the same approach to the seven
SinS.

The most probable candidates for adaptations are persistence and
transience. To the extent that persistence originated as a response to lifethreatening situations that posed a direct threat to survival, animals and
people who were able to remember those experiences persistently would
surely be favored by natural selection. This ability seems so basic that if it
did originate as an adaptation, we would expect many species to have neural machinery dedicated to preserving the memory of life-threatening experiences for long periods of time. As noted earlier, the universal presence
of a particular feature across numerous cultures does not necessarily indicate that the feature is an adaptation, but it does provide one telltale sign
of an adaptation. The neurobiologist Joseph LeDoux has noted that the
amygdala and related structures are involved in long-lasting fear learning
across diverse species, including humans, monkeys, cats, and rats. Likewise,
we might also expect to observe links among persistence, the amygdala,
and arousing or threatening experiences across diverse cultures and social
groups. I am not aware of any evidence that addresses this issue directly,
but cross-cultural studies examining neurobiological and cognitive aspects
of persistence represent a promising avenue for future research. Consider
also that, as discussed in Chapter 7, persistence results from a finely tuned
interplay between the amygdala and stress-related hormones which modulates memory formation - an interdependent system that is suggestive of
complex design.

The arguments of John Anderson and his group support the possibility that transience, too, could be an evolutionary adaptation. As mentioned
earlier, Anderson's argument rests on the idea that properties of transience
reflect properties of the environment in which memory operates. There is a
catch here, however. If transience is an adaptation that arose through selection, then its properties should reflect those of the ancient environments
in which our ancestors evolved. But how could we ever know about the
relevant properties of environments during the hunter-gatherer period
or other even earlier periods that may be relevant to human evolution?
Not easily. Some anthropologists study contemporary foraging groups that
remain culturally isolated, such as the Matsigenka indigenous people in
southeastern Peru. If patterns of information retrieval in such groups could
be examined, the results would help to determine whether transience reflects properties of environments more akin to ancestral environments,
rather than modern Western societies. I am not aware of any such studies.
However, the cognitive psychologist Lael Schooler, who has collaborated
with Anderson on the idea that memory reflects environmental properties,
has tried to get at the issue from a different but related angle.

Schooler drew on data collected by his collaborators Ramon Rhine
and Juan Carlos Serio Silva concerning primate behavior in two separate
environments that are similar in important respects to environments in
which our hominid ancestors evolved: a tropical forest and a savanna. They
studied the ranging behavior of howler monkeys living in a tropical forest
on the volcanic island of Agaltepec in Mexico, and baboons living in the savanna and open plains of Mikumi National Park in Tanzania. At both sites,
the researchers observed the ranging behavior of troops of howlers and baboons over a period of several months as they moved from location to location. Schooler, Rhine, and Silva then analyzed the likelihood that a troop
would return to a particular location as a function of the number of days
that had passed since they were last there. The probability of returning to a
particular location declined as time went on, and the form of the curve was
similar to that observed for forgetting. As with the modern environments
studied by Anderson and Schooler, the tropical forest of Agaltepec and the
savanna of Mikumi appear to be environments in which it is an increasingly good bet to forget about information that hasn't been used for everlonger periods of time. We don't know whether the similar patterns are
based on independent mechanisms in modern humans and ranging primates, or whether they reflect a common evolutionary origin. Nonetheless,
these observations encourage the view that transience is an adaptation to
enduring properties of environments inhabited by both modern and ancient primates.

In her analysis of positive illusions, Shelley Taylor has suggested that
overly optimistic biases may also be evolutionary adaptations. However,
the University of Pennsylvania psychologist Steven Heine and his collaborators have presented evidence that casts some doubt on this possibility.
They suggest that biases to view the self in an overly positive manner are
specific to certain cultures. For example, they cited anthropological, sociological, and psychological evidence that the Japanese tend to adopt a critical view of the self, rather than the positive bias commonly seen in studies
of North Americans. If positive biases were evolutionary adaptations, we
would expect to observe such biases across cultures. Although, as noted
earlier, a single exception to a universal pattern does not rule out the possibility of an adaptation, this line of work suggests that cross-cultural studies
of the various forms of memory bias could prove to be highly informative.

Bias is closely related to high-level cognitive operations and complex
social interactions (see Chapter 6). These are precisely the kinds of processes that we would expect to vary considerably among cultures. Based on
the work of Heine's group, I predict that the specific form of memory biases will be found to vary considerably across cultures, and is more likely
the product of social and cultural norms than biological evolution produced by natural selection. It is still possible, however, that people in all
cultures exhibit some type of bias during remembering, with the particular
type or content of bias varying across cultures. Even if this is so, however, I
hypothesize that bias is an incidental by-product of the fact that general
knowledge and beliefs frequently guide acts of remembering.

I hypothesize that the remaining sins - blocking, absent-minded204 ness, misattribution, and suggestibility - are most likely evolutionary
spandrels. Part of my reasoning is driven by plausibility considerations: it
is difficult to imagine how or why natural selection would design a system that is especially prone to absent-minded errors, frequently blocks on
names or words, or remembers events that never occurred. But we have already seen that each of these sins can be plausibly viewed as a by-product
of useful features of memory that themselves arose as either adaptations or
exaptations. Absent-minded errors, misattribution resulting from source
memory confusion, and related effects of suggestibility are, I suggest, byproducts of adaptations and exaptations that produced a memory system
that does not routinely preserve all the details required to specify the exact
source of an experience. Blocking may be an incidental by-product of effects related to recency and frequency of information retrieval that also give
rise to transience. And gist-based false memories are by-products of categorization and generalization processes that are themselves vital to our
cogniti'/e function.

There is a difference, however, between these spandrels of memory
and the architectural spandrels discussed by Gould and Lewontin. Architectural spandrels have benign consequences: they do not interfere with or
undermine a building's structural or functional integrity. Not so for memory, however. The irritation of absent-minded errors, the momentary frustration of blocking, and the potentially shattering consequences of eyewitness misidentifications and false memories resulting from misattribution
or suggestibility all have the power to disrupt our lives, temporarily or permanently. When suffering the consequences of these spandrels gone awry,
it is difficult to appreciate or imagine that they are by-products of processes
that, for the most part, keep our cognitive lives running smoothly. It may
be helpful to think of these memory spandrels in relation to the squirrel
that weighs the benefits of feeding against the possible costs of encountering a predator and returns to cover repeatedly with bits of cookie. The misbegotten spandrels represent the cost of a trade-off in memory which also
has important, though less visible, benefits.

If my suggestions about the origins of the seven sins have merit, one
thing we can count on is that the sins are not going to disappear any time
soon. Recall the case of Binjimin Wilkomirski: he "remembered" childhood
terrors experienced in a Nazi concentration camp, when he actually appears to have lived safely in Switzerland during the war. The prospect of
someone falsely recollecting that he endured one of the greatest horrors
imaginable seems so bizarre that one is tempted to write off Wilkomirski as
an inexplicable, one-time aberration. But if misattribution and suggestibility, the likely culprits in Wilkomirski's delusions, are truly evolutionary
spandrels, then Wilkomirksi should not be an isolated case. And he is not.
Women and men who once believed that they had recovered memories of
terrible childhood traumas, only to later retract them after ending psychotherapy, remind us that Wilkomirski's experience is far from unique. So,
too, do the legions of self-proclaimed alien abductees, who vividly remember impossible events such as sexual abuse at the hands of demonic - and
elusive - alien captors. Suggestive procedures such as hypnosis are frequently implicated in such cases.

These types of false memories are nothing new. In Chapter 4, we considered the debate over false memories and deja vu which raged in the
1890s. As early as 1881, the British psychologist James Sully devoted an entire chapter of his book, Illusions: A Psychological Study, to "illusions of
memory," citing case after case of memory distortions that exemplify what
I call misattribution and suggestibility. The historian Patrick Geary described an eleventh-century Bavarian monk named Arnold who "remembered" encountering a flying dragon on a journey he made years earlier. Arnold's false memory was likely the product of imagination and suggestion.
Misattribution and suggestibility have been with us for a long time, and
will surely continue their mischief in the future.

The same applies to the other sins. Consider, for instance, transience
and persistence. People have been trying to overcome the limitations of
transience for centuries. As I noted in Chapter 1, the invention of visual imagery mnemonics - a method of improving memory by encoding new information in the form of vivid visual images - dates to the Greeks. Similarly, persistence has a long heritage. Recall Robert Burton's description of
the terrified Blasius, a reporter who witnessed the ancient earthquake at
Sacai, and for years afterward could not "drive the remembrance of it out
of his minde" (see Chapter 7). Post-traumatic stress disorder - where the
effects of persistence are painfully magnified - has achieved recognition
only recently from psychologists and psychiatrists. Yet its symptoms have
probably been around as long as people have experienced trauma. This idea
is wonderfully illustrated by the psychiatrist Jonathan Shay's compelling
book, Achilles in Vietnam, which delineates parallels between the aftermath
of combat trauma in Vietnam and in Homer's Iliad. Shay relates an incident where Achilles is overwhelmed by grief because he failed to cover for a
fellow soldier who died, and feels "pierced by memory" as he intrusively remembers his fallen comrade.

Even though they often seem like our enemies, the seven sins are an
integral part of the mind's heritage because they are so closely connected to
features of memory which make it work well. The seemingly contradictory
relationship between memory's sins and virtues captured the attention of
Fanny Price, the heroine of Jane Austen's nineteenth-century novel Mansfield Park. Admiring a beautiful shrub-lined walkway that had emerged
from a formerly rough patch of ground, Fanny recalled what the walkway
had looked like years earlier, and wondered whether she would lose this
memory in the future. The moment inspired her to contemplate seemingly
contradictory properties of memory:

If anyone faculty of our nature may be called more wonderful than the
rest, I do think it is memory. There seems something more speakingly
incomprehensible in the powers, the failures, the inequalities of memory, than in any other of our intelligences. The memory is sometimes
so retentive, so serviceable, so obedient; at others, so bewildered and so
weak; and at others again, so tyrannic, so beyond control! We are to be
sure a miracle every way - but our powers of recollecting and of forgetting, do seem peculiarly past finding out.

Modern psychology and neuroscience have proven Fanny wrong on
one point - that our powers of recollecting and forgetting are "peculiarly
past finding out" - but her acute appreciation of memory's contrasting
strengths and weaknesses could hardly be more apt. The seven sins are not
merely nuisances to minimize or avoid. They also illuminate how memory
draws on the past to inform the present, preserves elements of present experience for future reference, and allows us to revisit the past at will. Memory's vices are also its virtues, elements of a bridge across time which allows us to link the mind with the world.

7. The Sin of Persistence.

7. The Sin of Persistence.

ON A SUNNY AFTERNOON in early October 1986, a jubilant crowd of baseball fans cheered as the hometown California Angels neared victory ver the Boston Red Sox in the American League championship series. In he ninth inning of the series' fifth game, the Angels held a seemingly insurmountable advantage: leading by a score of 5 to 2, they needed only one
more win to clinch the series. But the Red Sox rallied, cutting the lead to 5 to 4 and putting a runner on first base with two outs. Trying to end the game, the Angels manager Gene Mauch summoned the ace reliever Donnie Moore from the bullpen to face the journeyman outfielder Dave Henderson. Moore quickly threw two strikes. Angels fans and players began to celebrate as the seemingly overmatched Henderson barely fouled off a pitch to
avoid striking out. With the odds stacked heavily against him, Henderson hammered Moore's next offering into deep left field for a game-winning home run. Moore, his teammates, and the crowd watched in disbelief as
Henderson trotted around the bases. The Angels failed to bounce back and the Red Sox advanced to the World Series.

With the passing of time, Angels players and fans eventually recovered from the deflating loss. But Donnie Moore never did. He was haunted, sometimes overwhelmed, by the memory of Henderson's home run.
Though his teammates tried to remind him of all the games he had saved during the season, Moore focused only on the fateful pitch, blaming himself for the team's defeat. Fans and media helped to strengthen the vivid
recollection by talking about the incident incessantly. Unable to shake the memory, Moore sank into an ever-deepening depression that undermined
his marriage and career. In July 1989, Moore's descent concluded violently. "Tormented by the memory of one pitch:' began a bulletin from the Associated Press, "and despondent over his failing career and marital troubles,
former California Angels pitcher Donnie Moore shot his wife numerous times before killing himself, police said:' Moore's agent, Dave Pinter, com mented that "Even when he was told that one pitch doesn't make a season, he couldn't get over it. That home run killed him."

Though Moore's downfall was probably not entirely attributable to this single incident, his demise nonetheless provides a dramatic example of
memory's seventh and perhaps most debilitating sin: persistence. In contrast to transience, absent-mindedness, and blocking, which entail forgetting information or events you wish you could remember, persistence
involves remembering those things that you wish you could forget. Sometimes, persistence is no more than a mild irritant. We've all had the experience of a tune or a song that we can't get out of our heads. We may at first
enjoy the experience, but as time goes on we tire of mentally "hearing" the persisting melody and attempt to banish the intruder from consciousness.
Sometimes these persistent memories can distract us from more important tasks. I recall feeling flustered as a high school student when a favorite Led
Zeppelin song kept running through my head in the middle of an exam, making concentration on the test almost impossible. Laurie Gordon, an
undergraduate in one of my Harvard seminars, recounted a similar annoyance and took steps to prevent its recurrence:

I was able to bring in a double-sided review sheet for one of my finals. I found that I had extra room on the sheet, since there wasn't much in ormation that would be useful to have during the exam. I decided to fill the extra space on the sheet with lyrics from 5 or so of my favorite
songs, so that I wouldn't run into the situation I had experienced the day before, when I had had difficulty concentrating because of an annoying song running through my head. Instead, when I took the exam,

I was able to block out this song by looking at the song lyrics that I had written on my review sheet.

Though irritating, the "tune-running-through-the-head" experience occurs relatively infrequently, most often does not have serious consequences, and can be managed effectively with techniques such as the one
that Gordon used. The type of persistence that overwhelmed Donnie Moore is far more troubling. Despite the extraordinary nature of Moore's
story, it nevertheless illuminates the primary territory of persistence: disappointment, regret, failure, sadness, and trauma. Experiences that we remember intrusively, despite desperately wanting to banish them from our
minds, are closely linked to, and sometimes threaten, our perceptions of who we are and who we would like to be.

HOT MEMORIES.

Because persistence is strongly linked with our emotional lives, to understand the seventh sin we need to consider the relationship between emotion and memory. Everyday experience and laboratory studies reveal that
emotionally charged incidents are better remembered than nonemotional events. The emotional boost begins at the moment that a memory is born,
when attention and elaboration strongly influence whether an experience will be subsequently remembered or forgotten. As bouts of absent-mindedness illustrate, when we fail to attend to or eiaboratively encode incoming
information we stand little chance of remembering it later.

Experiments have shown that emotional information attracts attention quickly and automatically, illustrated nicely by experiments using a
variant of the famous "Stroop effect:' Write the word yellow in a yellow color, red in a blue color, green in a black color, and try to name the color in
which each of the words is printed. You will notice that you take longer to say "blue" and "black" than "yellow:' because you can't help but analyze the
meanings of red and green, which conflict with the colors you are trying to name. Something similar can happen with emotional words such as sad
and joy: compared with neutral words like wet, naming the colors of positive and negative words takes longer. The emotional words seem to draw attention automatically, which gets in the way of naming the color. In the
split second that it takes to read a word, its emotional significance is retrieved and evaluated, influencing how we name and encode it.

After this first-pass automatic evaluation, the significance of emotional information undergoes evaluation in relation to our current goals
and concerns. Goals may be short-term - striking out a batter to end a baseball game - or long-term, such as performing well during the course
of a baseball season to attain a higher future salary. When our actions prevent us from attaining our goals - as with Donnie Moore, we feel sadness, frustration, or disappointment. When they allow us to attain our
goals - imagine that Moore had struck out Dave Henderson we feel happiness and perhaps elation. When we relate a current experience to
short- or long-term goals, we engage in a kind of reflection and analysiselaborative encoding - that promotes subsequent memory for the experience.

Though memory for emotional events generally benefits from both automatic first-pass evaluation and later reflections, there's a cost. Consider
a bystander in a bank as a robbery unfolds. Attempting to escape, the crook brandishes a gun; feeling a rush of fear, the bystander instantly focuses on
the weapon. Consequently, she can later recall the gun's features in great detail. But when police ask for a description of the robber, the bystander
can summon only a hazy memory of his face - not enough information to help investigators. Psychologists call this phenomenon "weapon focus."
The emotionally arousing object draws attention automatically, leaving few resources to help encode the rest of the scene. Experiments have shown that
people usually remember well the central focus of an emotionally arousing incident, at the expense of poor memory for peripheral details.

The benefits of emotional arousal for subsequent memory extend to
both positive and negative events: we remember more high and low moments from our lives than mundane ones. And positive experiences, just
like negative experiences, tend to be remembered involuntarily and intrusively. Roughly 90 percent of college students who recorded emotional incidents in a diary reported that they later experienced at least some intrusive memories for both positive and negative events, with more intense
emotions producing more frequent intrusive memories. The difference,
of course, is that positive memories are usually welcome intruders - we
enjoy basking in the glow of a recent business success, athletic accomplishment, or romantic encounter - whereas negative memories are decidedly
not.

Psychologists have long debated whether positive experiences are
better remembered than negative ones, or vice versa. Though little such evidence has turned up so far, experiments conducted in my laboratory by
the psychologist Kevin Ochsner have revealed an intriguing qualitative difference between the two. He showed college students a series of positive,
negative, and neutral photographs, such as a smiling baby, a disfigured face,
or an ordinary building. On a later test, people recognized more of the
positive and negative pictures than the neutral ones, and recognized about
the same number of positive as negative items. But when Ochsner probed
the experimental participants more closely about why they claimed to
recognize a particular picture, differences between positive and negative
memories began to emerge. When people recognized positive pictures, they
tended to say that the pictures just seemed familiar; when they recognized
negative pictures, they reported detailed, specific recollections of what they
thought and felt when they originally encountered the item. If we tend to
remember negative events in greater detail than positive ones, then we may be at special risk for persistently retrieving painful particulars of those experiences we would like most to forget.

WHEN MEMORY HURTS.

Our chances of becoming chronically plagued by persistence depend in
part on what happens after an adverse experience. Over time, the sting associated with unpleasant events often fades. We've all endured difficult experiences the death of a loved one, rejection by a lover, failure at work
- that pain us mightily in the days and weeks after they occur. In the immediate aftermath, we may find ourselves reliving the painful incident to
the point of distraction, but the raw hurt eventually dissipates. Recent data
suggest that negative emotions may actually fade faster than positive ones.
Consider a study in which college students kept diaries of daily experiences,
rated the pleasantness and other features of the events, and then tried to remember the experiences and associated emotions at various times ranging
from three months to over four years after the incident occurred. Memory
for unpleasant emotions faded faster than memory for pleasant emotions.

Reminders of difficult experiences can slow the normal fading of
painful emotions over time. The great novelist Gabriel Garda Marquez
began his novel Love in the Time of Cholera with a tribute to one: "It was inevitable: the scent of bitter almonds always reminded him of the fate of
unrequited love:' Continual reminding can strengthen recall of the disturbing specifics of what happened to a point at which persistence becomes
unbearable. Reporters, fans, and the media hounded Donnie Moore for
months after Henderson's home run, making it impossible for him to find
relief in the usual benefits conferred by the passing of time. His teammate
Brian Downing blamed the media for reminding Moore unrelentingly.
"You destroyed a man's life over one pitch:' commented Downing ruefully
after learning of Moore's suicide. "All you ever heard about, all you ever
read about, was one pitch."

Reminders of unpleasant experiences can also induce us to engage in
what psychologists call "counterfactual thinking" - generating alternative
scenarios of what might have been or should have been. Anyone who has
invested in the stock market is likely familiar with the power of counterfactual thinking. You track a favorite stock as its price steadily rises. Finally,
you work up the nerve to invest, and in no time your worst fears are realized - the market begins a correction and you lose 20 percent from your
investment within a few days. As you helplessly watch the stock drop, you
become overwhelmed with regret over your hasty action. If only I had been
more patient and waited for the market to tumble, you chide yourself as
you relive the moments leading up to your decision to throw money after
the stock. You wake up at night ruminating about your decision, imagining
how happy you would have been had you decided to wait just one or two
more days to invest. Such counterfactual thinking can easily lead to the
kind of hindsight biases we considered in Chapter 6.

I experienced an unsettling episode of such counterfactual thinking
during a recent trip to a midwinter conference in Florida. Scheduled to return to Boston on a Friday night, I heard a weather report warn of a massive storm that would surely result in my flight's cancellation. Should I
leave the conference early and try to beat the storm to Boston, or relax and
enjoy another day or two of Florida sunshine? After some hesitation I
opted to out race the storm. The strategy almost worked: my flight was
cleared to land in Boston, and it looked as if I would arrive home ahead of
the blizzard. But conditions deteriorated rapidly, the pilot was unable to
touch down, and we ended up making an emergency landing in Maine.
Then I endured an eighteen-hour odyssey of waiting, another failed landing attempt, a diversion to Kennedy Airport in New York, and finally an
overnight limousine ride to Boston with several other flustered passengers.
Why didn't I stay in the sunshine, I kept thinking to myself as the situation
fell apart. Reflecting back on the moment when I decided to try to outrace
the storm, I imagined myself on the phone to the airline, making the now
clearly wise decision to remain in Florida a little while longer.

Persistent counterfactual thinking can be far more serious when people feel that they could have or should have acted to prevent a tragedy.
Friends and relatives of people who commit suicide, for instance, are frequently plagued by persisting counterfactual thoughts about what they
could have done or should have done to prevent a loved one from taking
his life. "Some survivors will blame themselves for not intervening:' concludes the British suicide expert Mark Williams, "and endlessly ruminate
on what they could have done to prevent it." Even after a loved one died
from an un treatable illness, grieving family members "found themselves
repeatedly reviewing, going over in their minds, the events leading up to
the death, often endlessly replaying the incident, as if by doing so they
could undo or alter the events that had occurred." One widow paralyzed
by persistent counterfactual thinking commented, "I go through that last
week in the hospital again and again. It seems photographed on my mind."
Consistent with these real-life examples, laboratory studies have revealed
that negative experiences result in higher levels of subsequent counterfactual, "if only" kinds of thinking than do positive experiences.

Persisting memories and counterfactual thinking almost invariably
accompany such overwhelming events as the death of a loved one. But responses to many kinds of disappointments and failures depend, at least in
part, on previous experiences that shape the way we view ourselves: even
relentless reminding of an unpleasant experience need not result in paralyzing counterfactual thinking or the kind of crippling persistence that undermined Donnie Moore. Consider the case ofJean Van de Velde. This previously unknown French golf professional captured international attention
in July 1999 when he led the prestigious British Open in the tournament's
final round. Standing on the eighteenth tee, Van de Velde held a commanding three-shot lead and seemed assured of victory, needing only to avoid a
complete disaster to win. Instead, he collapsed: wild shots into the remote
reaches of rough and water led to a triple-bogey eight as millions of golf
fans around the world watched incredulously. Van de Velde fell into a
three-way tie for the lead, and then lost the tournament in a playoff, completing the most stunning meltdown that professional golf had ever witnessed.

Recognizing the magnitude of the disaster, articles the next day in
London newspapers proclaimed that the bitter memory of his collapse
would torment Van de Velde for the rest of his life. But that's not what happened. Though shaken and disappointed in the hours and days after he lost
the tournament, Van de Velde did not become a prisoner of persisting
memory the way that Donnie Moore did. Nor did he endlessly engage in
counterfactual thinking about what he could have done or should have
done on the fateful eighteenth hole. Instead, he explained the rationale for
some of the controversial decisions he had made - decisions that backfired - and placed the experience in a broader perspective, noting that
golf is a game and only one part of his life. Van de Velde also enjoyed the
new fame he had achieved by contending in an event of international stature. "Maybe it's in my temperament," Van de Velde commented several
weeks later when reporters asked how he managed to handle the situation
so well and avoid endlessly reliving what had happened on the final hole. "I
don't live in the past."

The contrasting fates of Donnie Moore and Jean Van de Velde remind
us that long-lasting persistence is not an inevitable consequence of all
disappointments: how we respond to adversity, and whether we become
plagued by persistence, depends on how we evaluate and appraise what
happens to us. Psychologists refer to the compilations of past experiences
that influence current evaluations as "self-schemas:' Built up over years
and decades, self-schemas contain evaluative knowledge of our own characteristics. Consider whether the following words describe you: sad, optimistic, successful, or lethargic. To make such judgments, you consult a selfschema that contains relevant information based on individual experiences
and composite pictures from different stages of your life. Emotionally
healthy people tend to endorse more positive than negative words, whereas
depressed individuals endorse more negative than positive words. Depression is associated with a highly negative self-schema, resulting in a chronic
perception of oneself as an inadequate or flawed individual.

The great Russian poet Alexander Pushkin captured some of the searing emotions associated with intrusive memories that reinforce a negative
life script or self-schema:

And in the idle darkness comes the bite.
Of all the burning serpents of remorse;
Dreams seethe; and fretful infelicities.
Are swarming in my over-burdened soul.
And Memory before my wakeful eyes.
With noiseless hand unwinds her lengthy scroll.
Then, as with loathing I peruse the years.
I tremble, and I curse my natal day.
Wail bitterly, and bitterly shed tears.
But cannot wash the woeful script away.

A negative self-schema can easily lead to depression because it provides a rich network of knowledge that facilitates encoding and later retention of negative experiences. When depressed patients make judgments
about whether such words as failure or happy describe them accurately,
they later recall more of the negative words, but not more positive words,
than healthy controls. The Harvard psychologist Patricia Deldin has found
that depressed and nondepressed individuals show different patterns of
electrical brain activity during encoding of positive and negative information. Depressed patients, relative to healthy controls, showed larger electrical responses to negative than positive words. These differences, which occur during the fleeting moments when a new memory is born, create
conditions that favor persistent retrieval of negative experiences - which
in turn can heighten depressed mood, contributing to a self-perpetuating
and potentially vicious cycle.

We don't know whether Donnie Moore possessed an unusually negative self-schema that left him vulnerable to persistence, nor do we know
whether Jean Van de Velde possessed an exceptionally positive self-schema
that protected him from memory's seventh sin. But we do know that patients suffering from clinical depression are especially prone to persistence.
Studies carried out by the University of London psychologist Chris Brewin
and his associates reveal that depressed patients are much more prone to
intrusive memories of negative experiences than are healthy controls. In
one study, for instance, Brewin's group found that nearly all patients who
became depressed as a result of a recent death, health problem, or an incident of abuse or assault reported persistent and unwanted memories related to the precipitating event.

Brewin also examined intrusive memories in people who had recently
received a cancer diagnosis. Some of these individuals sunk into a severe
depression, others became mildly depressed, and still others did not develop depression. The severely depressed patients reported many more intrusive memories - mainly related to illness, injury, and death - than did
either the mildly depressed or non depressed patients. This intensified persistence could be attributable to the negative mood that prevails in a severe
depression. Laboratory studies have shown that current mood state influences the kinds of memories that people tend to retrieve: in happy moods,
recollections of positive experiences spring to mind more readily than recollections of negative experiences; the opposite tends to occur in dark
moods. The cancer patients' intrusive memories could also be related to
negative self-schemas that predispose patients to developing depression in
the first place: these patients may have a larger store of negative memories
than patients who prove emotionally resilient in the face of a cancer diagnosis. Once again, conditions are in place for a self-perpetuating cycle in
which negative self-schemas and moods create fertile ground for persistent
retrieval of negative memories, which in turn amplifies the severity of depression.

The University of Michigan psychologist Susan Nolen-Hoeksema and her collaborators have found that people with a "ruminative" style, who focus obsessively on their current negative moods and past negative events,
are at special risk for becoming trapped in such destructive self-perpetuating cycles. Those with a ruminative style endure longer episodes of depression than individuals who do little ruminating. For instance, prior to the
1989 Loma Prieta earthquake that shook the northern California Bay Area,
Nolen-Hoeksema measured mood and tendencies toward rumination in a
large group of college students. In the days and weeks following the destructive event, she assessed their moods and emotional responses. Students who exhibited a ruminative style before the earthquake were more
likely to be depressed weeks afterward than students who had not shown
signs of a ruminative style prior to the quake. More rumination after the
earthquake was linked with longer and more severe depression. NolenHoeksema observed something similar in caregivers of terminally ill patients, who are at great risk for depression. Caregivers who tended to ruminate on present and past negative events became more severely depressed
during the course of a terminal illness than those who did not.

Nolen-Hoeksema's group has recently linked rumination, depression,
and memory even more strongly. College students who were experiencing
depressed or nondepressed moods engaged in two types of tasks. The rumination task focused on students' current mood, energy level, and past
events that influenced them to turn out the way that they did. The distracting task drew attention away from the students' moods and concerns, requiring them to imagine the Mona Lisa's face or douds forming in the sky.
Students were then asked to recall autobiographical incidents from their
pasts. For students who were already experiencing a depressed mood, engaging in the rumination task led to recall of more negative autobiographical memories than did the distracting task.

Ruminative tendencies may explain some differences between the responses of men and women to depression. Nolen-Hoeksema monitored
episodes of depression in women and men for a month. She found that
women were more likely than men to ruminate over their depressed
moods; men were more likely to engage in distracting activities that drew
attention away from their negative moods, such as spending more time on
work or hobbies. High levels of rumination contributed to longer-lasting
and more severe depressive episodes in women than in men. Here again,
the vicious cycle of rumination, memory, and depression was at work.

Women ruminated by asking questions about why they were depressed,
thereby activating a wealth of negative memories: past experiences in
which they felt inadequate or otherwise saw themselves in a negative light.
These negative memories further deepened an already black mood, leading
to more prolonged and painful depression. By fleeing into distracting activities, men escaped this downward spiral.

It's important to distinguish between ruminating about a painful experience and disclosing it to others. Rumination involves a kind of obsessive recycling of thoughts and memories regarding one's current mood or
situation which produces an even worse outcome. Disclosing difficult experiences to others, however, can have profoundly positive effects. The psychologist James Pennebaker and coworkers at the University of Texas have
carried out studies in which people disclose troubling experiences by writing or talking about them for several days. The resulting narratives that
people create produce surprising benefits: more positive mood, enhanced
immune system functions, fewer visits to the doctor, higher grade point
averages, reduced absenteeism at work, and even higher rates of reemployment following job loss. Although the exact reasons for these benefits are
still a matter of debate, the findings suggest that the act of converting turbulent emotions into narrative form influences important physiological
systems.

The difference between generating useful narratives and endlessly ruminating is apparent in very severe or suicidal depression. Patients suffering from suicidal depression may have difficulty coming up with coherent
narratives because they persistently recall and ruminate over what the British psychologist Mark Williams calls "overgeneral memories." Several years
ago, Williams began conducting experiments on autobiographical memory
in suicidally depressed patients using a widely adopted word-cueing technique. Try to recall a specific incident from your life for each of the following words: happy, sorry, angry, and successful. Most people have no difficulty coming up with detailed recollections of particular experiences. In
response to happy, for instance, I recalled how pleased I felt when I watched
my daughter Hannah score six points during a recent game in her fourthgrade basketball league. For sorry, I remembered how bad a professional acquaintance felt when she lost a set of slides I used to deliver a lecture at her
university.

Williams noticed that severely depressed patients rarely generated
memories of specific incidents in response to either positive or negative
cues - even though, as we saw earlier, Kevin Ochsner's results suggest that
the natural tendency is to remember negative events in great detail. Instead,
they came up with summary descriptions, such as "when I do things
wrong" in response to the cue sorry, or "my father" in response to happy.
Williams notes that persistent retrieval of overgeneral memories can contribute to an eventual decision to commit suicide. An unpleasant event that
turns out to be the final straw in a suicidal decline can stimulate recall and
rumination about negative overgeneral memories, such as "I've always
been a failure" or "Nobody's ever really liked me." A patient may be overwhelmed by persistent recall of such self-damaging descriptions, which
dominate the patient's mind and lead to a decision to take his own life.

Studies of brain activity in depressed patients provide some clues concerning possible underlying bases of persistent overgeneral memories. Several studies have found that depressed patients show relatively reduced activity in parts of the left frontal lobe, mainly on the lateral surface (the
dorsolateral frontal region), either when they are resting comfortably or
performing cognitive tasks. Patients who suffer strokes to the left frontal
lobe often become depressed, whereas patients with right frontal damage
typically do not become depressed. The affected regions in the left frontal
lobe may playa role in the generation of positive emotions.

From the standpoint of memory, neuroimaging studies suggest that
similar regions in the left prefrontal cortex playa role in reflecting back on
past experiences and retrieving specific aspects of what happened. In studies conducted by the Yale University psychologist Marcia Johnson and her
group, the amount of activity in the left prefrontal cortex during retrieval
was greatest when people recalled particular details of past episodes. If severely depressed patients have more trouble activating key regions of the
left frontal lobe, they may be particularly vulnerable to persistent recall of
overgeneral memories. A healthy individual might be able to counter retrieval of negative memories by recalling a specific positive experience. If,
having had a paper rejected from a scientific journal, I am reminded of
previous rejections and conclude that I am a lousy researcher, I still can
generate specific memories of papers that journal reviewers accepted enthusiastically. Supported by these positive memories, I begin to feel better
about my abilities and resolve to revise the rejected paper for publication
elsewhere. But if I am depressed and thus unable to generate specific recollections, I could well become overwhelmed by intrusive overgeneral memories that match my despairing mood - "I've always had problems publishing in the top journals;' "I feel like a failure again" - further increasing
my sense of despair. A dysfunctional left frontal lobe might well contribute
to this destructive cycle.

Persistence, then, thrives in an emotional climate of disappointment,
sadness, and regret. But to witness the full force of the seventh sin, we need
to turn our attention to the world of traumatic experiences.

TERROR IN THE PAST.

In Sacai ... the ... earthquake was so terrible unto them, that many
were bereft of their senses; and others by that horrible spectacle so
much amazed, that they knew not what they did. Blasius, a Christian
the reporter of the newes, was so affrighted for his part, that though it
were two months after, hee was scarce his owne man, neither could hee
drive the remembrance of it out of his min de. Many times, Some years
following, they will tremble afresh at the remembrance or conceipt of
such a terrible object, even all their lives long, if mention be made of it.
In his classic seventeenth-century treatise, The Anatomy of Melancholy, the
British writer Robert Burton described the devastating psychological consequences of an ancient earthquake. The experience of Blasius and others
in Sacai has been replicated countless times across centuries and millennia: traumatic experiences almost invariably result in intrusive, persisting
memories of a terrible event.

In the twentieth century, the damaging effects of traumatic experiences on memory and other mental functions were first recognized during
World War 1. Doctors began treating cases of "shell shock;' in which soldiers exposed to life-threatening situations later become incapacitated by
recurring nightmares and intrusive memories of their encounters with
death. After the war, the British government established a committee to determine whether soldiers who had been executed for cowardice had in fact
been suffering from shell shock. World War II produced another upsurge
in cases of shell shock, but what we now call post-traumatic stress disorder
became widely acknowledged and formally recognized by medical practitioners only after the conclusion of the Vietnam War. Hospitals and other
organizations charged with caring for returning veterans became inundated with cases in which intrusive war memories and recurrent batde
nightmares interfered with the ability of affected veterans to resume their
lives at home and to reintegrate with society.

Persisting memories are a major consequence of just about any type
of traumatic experience: war, violent assaults or rapes, sexual abuse, earthquakes and other natural disasters, torture and brutal imprisonment, motor vehicle accidents. Though such events may seem like relatively rare occurrences, epidemiological studies suggest that just over half of women and
60 percent of men will experience at least one traumatic event in their lives.
The intrusive memories that result from such experiences usually take the
form of vivid perceptual images, sometimes preserving in minute detail
the very features of a trauma which survivors would most like to forget.
Though intrusive recollections can occur in any of the senses, visual memories are by far the most common. The Oxford psychologist Anke Ehlers
studied the perceptual qualities of intrusive memories in people who had
been traumatized by sexual abuse or road traffic accidents. For both types
of trauma, visual recollections predominated in nearly all survivors, with
some remembering "single pictures" of the traumatic incident and a similar proportion recalling multi-image "film clips." Other senses still played
some role: more than half of both sexual abuse and traffic accident survivors reported experiencing intrusive memories in the form of smells,
sounds, or bodily sensation.

Post-traumatic stress disorder, or PTSD, is often associated with depression. Chris Brewin has direcdy compared intrusive memories in traumatized patients and in depressed patients who had not experienced a
specific trauma. Patients with PTSD reported more frequent intrusive
memories and flashbacks than did depressed patients, but the qualities of
the memories were generally similar in the two groups. Traumatized patients, however, reported more unusual dissociative experiences, in which
they felt as though they were observers watching an event happen to someone else.

Studies of trauma survivors indicate that nearly all of them experience
troubling intrusive memories in the days and weeks after a trauma occurs.
But, just as we saw with Jean Van de Velde, not everyone continues to be
plagued by intrusive recollections months, years, or decades later. Those
who continue to experience intrusive memories long after a traumatic
event, and who as a result cannot return to normal functioning in their
everyday lives, are likely to receive a diagnosis of post-traumatic stress disorder.

For some people, the force of a traumatic event is so compelling that
they become "stuck" in the past. Studies of Vietnam veterans and victims
of sexual abuse indicate that individuals who remain focused on the past
for years after a traumatic event exhibit higher levels of psychological distress than those who focus on the present and future. High levels of psychological distress in turn stimulate even greater focus on the past, thus
setting up a destructive self-perpetuating cycle of persistent remembering
like that observed in cases of depression.

The likelihood of getting stuck in the past depends in part on how a
person responds in the immediate aftermath of a trauma. Recall the terrible 1993 firestorms in southern California which destroyed vast swathes of
property, threatened lives, and forced scores of people to abandon their
homes. Alison Holman and Roxane Silver of the University of California at
Irvine interviewed survivors of the firestorms in nearby Laguna Beach and
the Malibu-Topanga area of Los Angeles within a few days of the disaster,
and then followed up six: months and one year later. Immediately after the
fires, some survivors reported disturbances in their sense of orientation in
time: they felt that time had stopped or that the present was no longer continuous with the past or the future. People who experienced high levels of
such "temporal disintegration" immediately after the firestorms were especially likely to focus on and ruminate about the event six: months later. A
year after the firestorms, these same individuals experienced more distress
than did people who were able to focus more on the present or future in the
intervening months. Temporal disintegration in response to a trauma thus
foreshadowed later troubles in people who remained stuck in the past, prisoners of persistent memories.

Long-term psychological trouble can also result from attempting to
avoid thinking about a traumatic event in its immediate aftermath. The
overwhelming pain of a traumatic experience and associated intrusive
memories naturally leads people to want to avoid reminders of the incident
and, if possible, to suppress trauma-related memories and thoughts. Consider the protagonist in Sarah Van Arsdale's 1995 novel Toward Amnesia.
Libby has recently been abandoned by her lover and is trying to deal with
persisting memories of their relationship. She devises a plan of psychological escape from memories that burden her continually. "It was on Memorial Day I decided to achieve amnesia:' the novel begins. First trying to
attain this goal by simply admonishing herself to forget - 'Td gotten
through ... by chanting that mantra or the other one: forget, forget, forget" - Libby eventually flees the ever-present reminders of her relationship, driving hundreds of miles to Canada in order to seek refuge from
memory.

Though the prospect of forgetting may seem soothing after a disappointment or trauma, such attempts are likely to backfire. Consider a
group that is at high risk for intrusive traumatic memories: emergency
service personnel. Ambulance crews, firefighters, and disaster relief workers are frequently exposed to upsetting, sometimes overwhelming, events.
In a study of ambulance workers, Anke Ehlers and her collaborators found
that virtually all of them experienced some work-related intrusive memories. The most common sources of intrusive memories were accidents involving the loss of children or acquaintances, violent deaths, severe burns,
or failed attempts to save a life. But despite the ubiquity of persisting traumatic memories in ambulance workers, just one in five of Ehlers's sample
met the criteria for PTSD. These individuals often responded initially by
trying to avoid remembering the trauma. They tended to interpret their
traumatic recollections as an indication that they were going mad or otherwise unraveling. Instead of working through the traumatic event initially,
they retreated into wishful thinking, sometimes trying to alter or undo the
past in fantasies. Yet attempts to avoid distressing memories resulted in
only more rumination and distress with the passing of time.

These observations fit nicely with pioneering laboratory studies conducted by the Harvard psychologist Daniel Wegner concerning paradoxical
or ironic effects of attempting to suppress unwanted thoughts. In Wegner's
experiments, people are instructed to try to avoid thinking about a particular topic - a neutral concept such as a white bear, or a personally meaningful one like an old flame. Wegner finds that following a period of
thought suppression, participants in his experiments usually show a "rebound effect": they later think about the forbidden subject more often and
intensely than they would have if they had never attempted to suppress
thinking about it in the first place. "Although not thinking about painful
thoughts may seem like a reasonable coping strategy to adopt:' comments
Wegner, "trying to forget might not only prolong the misery, but make it
worse." Wegner's ideas are backed up by other studies showing that after
exposure to distressing films, people who are instructed to suppress
thoughts related to the film later experience more film-related intrusive
memories than those who do not try to suppress. Attempts to avoid thinking about a horrendous experience are common in trauma survivors, but
are more likely to amplify, rather than lessen, later problems with persisting
memories.

One possible reason for this phenomenon is that reexperiencing a
traumatic event in an otherwise safe context can take out some of the sting.
Repetition of just about any stimulus or experience will result in what researchers call habituation - a reduced physiological response to the stimulus. If I playa loud sound for you at regular intervals and record physiological activity, at first you will show a strong response to the sound,
followed by a gradual drop-off. The same goes for traumatic memories: repeated reexperiencing of a traumatic memory in a safe setting can dampen
the initial physiological response to the trauma. Attempts to suppress
memories of upsetting experiences prevent this normal process of habituation. Suppressed recollections thus retain an extra charge that eventually
augments persistence.

Perhaps not surprisingly, then, therapeutic attempts to counter persistence in trauma survivors almost invariably focus on allowing patients to
reexperience the traumatic event within the safe confines of the therapy
setting. The approaches that have proven most effective are imaginal exposure therapies: patients are repeatedly exposed to stimuli associated with
their traumas and they recall and reexperience vivid images of the incidents. In the early 1980s, the Boston psychologist Terrence Keane and his
associates reported that exposure therapy reduced levels of anxiety and intrusive memories in Vietnam veterans, and others reported similar effects
in survivors of sexual abuse. Later studies directly compared imaginal exposure therapy to other kinds of treatments that do not involve repeated
reexperiencing of trauma, such as supportive counseling. Keane's group
and another team led by the psychologist Edna Foa found that exposure
therapy produced the greatest reductions in intrusive memories, flashbacks, and related symptoms of PTSD.

The psychiatrist Stevan Weine and his collaborators have recently described a related approach to reducing persistence in people who have been
traumatized by state-sponsored terrorism. Refugees who escaped the attempted genocide several years ago in Bosnia-Herzegovina often showed
classic symptoms of PTSD, including overwhelming intrusive memories.
Weine and his collaborators are exploring the effectiveness of what they call
"testimony therapy:' in which survivors retell and relive their traumatic experiences, and try to relate them to the traumas suffered by others in their
society. Weine's group gathered survivors' recollections into an oral history
archive that was shared with other patients as part of the testimony therapy
process. "Within this context, where the survivors explicitly understand
that their remembrances are becoming part of a collective inquiry:' observed Weine, "testimony can reduce individual suffering, even when survivors have not explicitly sought trauma treatment." Preliminary results indicate that testimony therapy does indeed produce reduced levels of intrusive
memories in traumatized Bosnian refugees.

These findings fit well with James Pennebaker's studies concerning the
beneficial effects of disclosing disappointments, losses, and other negative
experiences. In the short term, persistence is a virtually inevitable consequence of difficult experiences. But for the long term, confronting, disclosing, and integrating those experiences we would most like to forget is the
most effective counter to persistence.

THE ROOTS OF PERSISTENCE.

To understand better why traumatic events produce such powerful persistence in the first place, it's helpful to consider the neural systems involved
in remembering trauma. A key player in the brain's response to traumatic
events is a small almond-shaped structure called the amygdala. Buried
deep in the inner regio~s of the temporal lobe, the amygdala abuts the
nearby hippocampus, but performs quite different functions than does its
neighbor. Recall that when people sustain damage to the hippocampus and
surrounding cortical areas, they almost invariably suffer a general impairment in forming and later retrieving new episodic memories of personal
experiences. Damage to the amygdala does not result in this sort of global
memory deficit: patients with amygdala damage can remember their recent
experiences with little difficulty. The memories of patients with amygdala
damage, however, do not benefit from the emotions that normally accompany an arousing experience and aid subsequent recollection. Consider
what happens when healthy people view a slide sequence that begins mundanely - a mother walking her child to school - and later includes an
emotionally arousing event: the child is hit by a car. When tested later,
healthy people remember the arousing event better than the mundane
ones. Patients with amygdala damage remember the mundane events normally, but do not show improved memory for the emotionally arousing
event.

Abnormal fear responses are a hallmark of amygdala damage: patients
have great difficulty learning to fear situations that would normally scare
the rest of us. Consider a rape victim who begins to experience fear and
distress every time she drives near the park where she was assaulted. There
is nothing inherently frightening about this particular park, but for the
rape survivor it has become inextricably associated with trauma. Researchers have created experimental analogues of fear learning by using conditioning procedures that expose people or animals to normally innocuous
stimuli that are associated with a fear-inducing event. The procedures are
based on the famous conditioning experiments conducted in the early
1900S by the Russian physiologist Ivan Pavlov. Pavlov's dogs learned to salivate at the sound of a bell because it was previously associated with the enjoyable experience of gnawing on a piece of meat. Something similar happens with fear. Imagine that I show you a series of colored slides, and that
every time you see a blue slide you also hear the jolting sound of a loud
horn. It won't be too long before the appearance of a blue slide will induce
an emotional response, as you begin to dread the occurrence of the obnoxious sound. Researchers can measure this reaction by monitoring skin conductance responses, which provide a rough-and-ready index of emotional
arousal.

When patients with amygdala damage participated in this kind of
conditioning procedure, they did not show any signs of fear or emotional
arousal with repeated presentations of the blue slides. The psychologist
Elizabeth Phelps videotaped one such patient who had just participated in
a similar conditioning procedure. The patient knew perfectly well that
whenever the blue slide appeared, a loud unpleasant sound would begin to
blare. "Blue slide, loud sound;' she confidently announced to Dr. Phelps.
Nonetheless, the patient showed no signs of fear learning - physiological
arousal in response to the blue slide - at any time during the conditioning
experiment.

These findings fit neatly with numerous studies in rats and other experimental animals showing that damage to the amygdala disrupts fear
conditioning. When a normal rat receives an electric shock after hearing a
particular tone, it will soon behave fearfully upon hearing the tone alone.
The neuroscientist Joseph LeDoux, who has performed pioneering studies
on fear conditioning, provides a vivid description of a terrified rat:

After very few such pairings of the sound and the shock, the rat begins to act afraid when it hears the sound: it stops dead in its tracks
and adopts the characteristic freezing posture - crouching down and
remaining motionless, except for the rhythmic chest movements required for breathing. In addition, the rat's fur stands on end, its blood
pressure and heart rate rise, and stress hormones are released into its
bloodstream. These and other conditioned responses are expressed in
essentially the same way in every rat.

leDoux and others have discovered that selectively damaging specific
regions within the amygdala eliminates these telltale signs of fear. leDoux's
group has further shown that memories created during fear conditioning in healthy animals are exceptionally durable - perhaps even indelible.
Combined with the work on brain-damaged patients, these observations
suggest that the amygdala plays a role in generating the kinds of persisting
memories that haunt survivors of traumatic events.

As leDoux points out, the amygdala is well positioned to guide evaluation of the personal significance of incoming information - the essence
of emotional responding. He likens the amygdala to the hub of a wheel: it
receives raw sensory information from the thalamus, a key subcortical
switching station; more extensively processed perceptual information from
higher-order areas in the cortex; and signals from the hippocampus about
the general context of an event. Alerted by this converging information, the
amygdala can flag the occurrence of a significant event.

The amygdala also has a powerful influence on hormonal systems that
kick into high gear when we are confronted with a frightening or otherwise
arousing event. The release of stress-related hormones, such as adrenaline
and cortisol, mobilizes the brain and the body in the face of threat or other
sources of stress, and also enhances memory for the experience (probably
by influencing the activity of the hippocampus). When the amygdala is
damaged, however, stress-related hormones no longer produce any memory enhancement. The amygdala thus regulates or modulates memory
storage by turning on the hormones that allow us to respond to and remember vividly - but sometimes intrusively - threatening or traumatic
events.

Neuroimaging techniques are beginning to provide new insights into
the role of the amygdala and other brain structures in persistent memories
of traumatic events. Several studies using PET and fMRl have shown that
the amygdala is strongly activated by the presentation of aversive materials:
pictures of mutilated bodies, film clips of traumatic events, even faces with
angry or fearful expressions. These neuroimaging studies are particularly
intriguing, because seeing a face with a fearful expression does not necessarily elicit an emotional response from the viewer. Experiments by the
University of Wisconsin neuroscientist Paul Whalen and his coUaborators
reveal that even when fearful faces are presented so briefly that people do
not consciously discern the expression - participants report that they see
"expressionless" faces - the amygdala still shows greater activity for fearful faces than for happy faces. These and related results led Whalen to propose that the amygdala is turned on by events that signal a possible threat
in the environment.

When the amygdala lights up during threatening or aversive events,
the amount of activity predicts how well people later remember these experiences. Larry Cahill and James McGaugh at the University of California at
Irvine performed PET scans while people viewed film clips containing both
neutral and upsetting episodes. Later, participants tried to recall episodes
from the film. The amount of activity in the amygdala was closely correlated with the number of upsetting episodes that people recalled: the more
amygdala activity during film clip viewing, the more aversive incidents
later recalled. They found no such relationship for neutral incidents (interestingly, the amount of activity in the hippocampus correlated with subsequent recall of neutral, but not aversive, incidents).

Neuroimaging studies have also shown that, consistent with studies of
rats and other animals, the amygdala is strongly activated during fear conditioning. It is perhaps not surprising, then, that several imaging studies of
trauma survivors, including Vietnam War veterans and victims of sexual
abuse, have also documented amygdala activation when survivors recalled
and relived traumatic events that they remember intrusively in their everyday lives. Imaging studies also reveal heightened activity during traumatic
recollections in several other brain regions thought to playa role in fear
and anxiety - one tucked deep down in the frontal lobe, another near the
tip of the temporal lobe. These findings can help to explain why persistent
recollections of trauma often preserve the intense fear and anxiety that prevailed during the original experience.

Consistent with animal studies implicating stress-related hormones in
fear conditioning, studies of trauma survivors have also related these hormones to intrusive recollections. When stress-related hormones spring into
action during an emotionally arousing experience, they stimulate the release of a class of chemical messengers known as catecholamines. Researchers have focused in particular on the role of norepinepherine, one of
the major catecholamines. Several studies of Vietnam veterans and victims
of sexual abuse have found that greater levels of norepinepherine (measured in urine samples) are associated with more frequent intrusive memories of traumatic experiences. Further, when traumatized patients were administered the drug yohimbine, which raises levels of norepinepherine in
specific brain regions, nearly half of the patients experienced overwhelming visual flashbacks of a traumatic event, often accompanied by fear and
even panic.

Yohimbine is available over the counter in pharmacies and health
food stores, where it is marketed as an aphrodisiac, a remedy for male impotence, and a general energy booster. Several PTSD patients who purchased the drug experienced unexpected flashbacks and panic attacks. "I
felt like I was going crazy;' reflected one veteran who took yohimbine as an
aphrodisiac and instead found himself overwhelmed by unwanted war
flashbacks. "I kept thinking that my combat buddy was wounded. I kept
thinking that I was a medic and that I had to save him."

Though its effects are most dramatic in patients suffering from PTSD,
other studies have shown that giving normal volunteers yohimbine while
they view emotionally arousing slides enhances later recall of the emotional
events, probably by increasing levels of norepinepherine during encoding.
Norepinepherine supplies a chemical spark that ignites intrusive recollections.

Understanding the chemical and hormonal bases of persistence also
provides clues about how to counter it pharmacologically. If yohimbine or
other substances that boost stress-related hormones and norepinepherine
also heighten persistence, then it stands to reason that substances that
lower stress-related hormones and norepinepherine should reduce persistence. This result is exactly what Larry Cahill and James McGaugh found in
a study in which they administered a drug - the beta-blocker propranolol
- that prevents the release of stress-related hormones. Some participants
watched a slide show depicting mundane events, whereas others watched a slide show in which an emotionally arousing event was interposed among
the mundane ones. The group that received propranolol remembered the
mundane events about as well as a group that received an inactive placebo
pilL But an important difference also emerged: memory for the arousing events improved substantially in the placebo group, but not in the
propranolol group. Propranolol effectively blocked the usual memoryenhancing effects of emotional arousal.

These results raise the intriguing possibility that beta-blockers such as
propranolol could be administered to trauma survivors in order to reduce
persisting memories. Beta-blockers might also be given ahead of time to
emergency workers before they enter a disaster site, and thus thwart altogether the development of intrusive memories that will plague them later.
These are exciting possibilities because intrusive memories can be so crippling for long periods of time. And for emergency or disaster personnel
who are repeatedly exposed to potential sources of persistence, preliminary
administration of beta-blockers might make a highly stressful occupation
more manageable.

But this strategy for countering persistence also poses risks. We've
seen that attempts to avoid traumatic memories often backfire. Intrusive
memories need to be acknowledged, confronted, and worked through in
order to set them to rest for the long term. Unwelcome memories of
trauma are symptoms of a disrupted psyche that requires attention before
it can resume healthy functioning. Beta-blockers might make it easier for
trauma survivors to face and incorporate traumatic recollections, and in
that sense could facilitate long-term adaptation. Yet it is also possible that
beta-blockers would work against the normal process of recovery: traumatic memories would not spring to mind with the kind of psychological
force that demands attention and perhaps intervention. Prescription of
beta-blockers could bring about an effective trade-off between short-term
reductions in the sting of traumatic memories and long-term increases in
persistence or related symptoms of a trauma that has not been adequately
confronted.

For all its disruptive power, persistence serves a healthy function:
events that we need to confront come to mind with a force that is hard to
ignore. The seventh sin - just like the other six - is not merely an inconvenience or annoyance, but is instead a symptom of some of the greatest
strengths of the human mind.