The Making of the Mind: The Neuroscience of Human Nature (19 page)

Now, try to imagine what you will be doing at 10 a.m. one year from now. Is the process similar to recalling the past? Or imagine what your birthday party will be like ten years from now? The means by which the brain envisions the future is by recalling a similar situation from the past and modifying it appropriately. Cognitive neuroscientists have found that when envisioning the future, subjects reported situating the event in the context of familiar places, such as home, school, or work, and familiar people, such as friends and family.
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In doing so, they were able to reactivate images from personal past experience and then modify them in ways that fit their expectations for the future.

Not only did their introspective reports reveal this phenomenon of constructing the future by reconstructing the past, but fMRI images of the brain confirmed it. The same neural regions that were activated in recalling the past appeared when the subjects were asked to imagine the future. These were
the medial prefrontal cortex, the posterior cingulate cortex, the medial temporal cortex surrounding the hippocampus, and the occipital cortex in the left hemisphere.
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In addition, an entirely new set of brain regions are activated in envisioning the future—these regions seem to be much the same as those observed when people are asked to simulate bodily movements. It seems as if the brain must actively simulate movements of the body in trying to form mental images of the future. In recalling events from the past, the bodily movements had actually once been experienced, so such imagined simulation is unnecessary.
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Of interest, this use of past episodic memories to see the future only occurs when the self is part of the memory. The self-concept and its close ally, the interpreter, are essential for the operation of episodic memory and its capacity for mentally traveling backward and forward through time. When the subjects were asked to imagine an event in the future with which they have no personal past experience, the results were different. They were asked to imagine not their own birthday in the future, but rather the birthday of a famous person, namely, Bill Clinton. The images generated in cases like this were less detailed and drew upon general knowledge stored in semantic memory rather than autobiographical knowledge. For example, subjects tended to report seeing Bill Clinton at a party in the White House, but the other guests were faceless and unknown to them.
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This is indicative of drawing on a schema about birthdays from semantic memory but not engaging the interpretative self to construct the details needed for a true episodic experience of the future. Thus, when imagining one's future by traveling forward in time, episodic memory and the interpreter play a prominent role, but they do not when one imagines the future scenarios of a nonpersonal nature. The neuroimages of the brain confirmed this difference in reported mental experiences as well.

To summarize, episodic memory can be thought of as way of simulating the perception of an event in the here and now. As in the perception of an event at hand, schemas provide expectations about the contents and order of the past event, allowing a simulation of what must have transpired. Because episodic memory allows one to travel forward in time as well as into the past, the human capacity to imagine a future event is also a simulation. Because a future event has no record at all in long-term memory, the task of simulation
is generally more challenging. One might start the imaginative process by reconstructing a similar event from the past and then modifying it as the mind projects into the future.

What areas of the brain become active when people are allowed to think about whatever they wish while neuroimaging of the brain takes place? Allowing the mind to wander as it will, instead of giving it a specific task to accomplish, reveals what cognitive neuroscientists call the default network of the brain.
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When the brain is left to mind its own business, what does it think about? Of interest, it often turns to thoughts about the self, both reflections on past events and fantasies about possible future events. The default network thus involves the medial prefrontal cortex, the posterior cingulate cortex, and the medial temporal cortex. Besides remembering autobiographical events and envisioning the future, the default network is also activated in theory of mind tasks, such as when one must adopt the perspective of another person. It appears that the brain draws upon the default network to support “internal mentation that is largely detached form the external world…constructing dynamic mental simulations based on personal past experiences such as used during remembering, thinking about the future, and generally when imagining alternative perspectives and scenarios to the present.”
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FALSE MEMORIES

Retrieval from long-term memory involves not only an effort to reconstruct the past, but also an attempt to monitor the source of the events that emerge from the reconstruction. Given that human memory uses the same mechanism for recollecting the past and for imagining the future, it is essential that we monitor whether the source of an experience is a result of past perception or of imagination. Without effective source monitoring, it is possible to confuse the two and believe that an imaginary event really happened. The reliability of episodic memory depends not only on having accurately stored information about one's past, but also on how well the information is retrieved and evaluated. The source of thoughts that come to mind must be monitored and attributed correctly to either reality or one's imagination.
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For example, suppose you remember an embarrassing situation involving a particular person.
That person is someone you know and encounter in real life, and also someone who on occasion appears as a figure in your dreams. So, did the embarrassing event really happen or did it occur only in a dream? Source misattribution refers to false memories resulting from just such confusions. Effective reality monitoring, then, is an important component of sound episodic memory.

Psychologists have found that the more often people imagine an event occurring, the more likely they believe it has actually been perceived.
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This again makes perfect sense given that our brain draws on common neural systems for perceiving an event in the present, reconstructing an event from the past, and imagining an event in the future. But it is problematic when the brain loses track of its time travel and mistakenly confuses imagination with perception. The more complex the event, the more perceptual detail there is to imagine and the easier it is to falsely remember it as actually having occurred. Those of us with especially vivid visual and auditory imagery are especially prone to these confusions of imagination with perception.
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Dramatic and highly consequential cases of false memory are part of contemporary society. Beginning in the 1970s and 1980s, allegations of childhood sexual abuse increased dramatically in frequency, including father-daughter incest.
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These allegations were unusual in that the victims claimed to have no recollection of the abuse until years after it had taken place. In some cases, the memories did not surface until the individual was in psychotherapy for other current problems, such as depression, anxiety, substance abuse, or eating disorders. Therapists treating the individual regarded these recollections as recovered memories—recovered from a process of repression that had pushed the sexual abuse out of awareness for years. In fact, some therapists encouraged their clients to reconstruct the painful events through a variety of techniques, including the use of hypnosis. They further warned their clients that worries over whether the reconstructed memories were actually just fantasies and not true memories were normal but not to be trusted. Thus, the techniques simultaneously encouraged memory recovery and discouraged monitoring for false memories.
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Encouragement to validate the recovered memories took the form of writing them down, vocalizing them to others in a group therapy session, or even publicly accusing the abuser.

It is unknown how many of these cases truly involved a repressed memory
of sexual abuse. Because the sexual abuse of minors is known be perpetuated by pedophiles, some of these cases conceivably could have involved memory repression. However, it is also possible that the recovered memories reflected a failure of source monitoring. In reconstructing the events, it is possible that the products of imagination became confused with reality. Elizabeth Loftus and Katherine Ketcham conveyed the experience of several women undergoing therapy to recover lost memories of abuse in what follows:

At first the pictures in their minds included one abuser, usually a father, mother, or brother; but eventually the images enlarged to include uncles, aunts, cousins, grandparents, ministers, friends, neighbors. In the beginning, when the memory was developing, the abuse involved touching, fondling, probing; but as time went by the panorama of images expanded to include penetration, rape, and sodomy. Eventually, for several of these women, the mental spectacle included satanic cults, sadistic tortures, blood-drinking rituals, even murder.
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How is it possible to determine whether a recovered memory is true, partly true, or complete fantasy? Despite all the advances in cognitive neuroscience, there is no known method for answering this question. Cognitive science has methods for producing, measuring, and understanding false memories in the laboratory. Researchers have also worked with police and lawyers to aid in determining whether a person's testimony should be believed. However, “nobody has developed a neurophysiological procedure that can be used to predict whether a single memory is true or false.”
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Although this may be possible in the future with improved batteries of tests and neuroimaging techniques, it is not now possible.

However, the theory that recovered memories are commonly a result of repression is problematic for two reasons.
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First, in some cases traumatic memories may be stored in a highly fragmented form that is susceptible to being forgotten. Yet to the extent that fragments are forgotten for a period of time and then recovered, the recollections are prone to the distortions and inaccuracies that typify our normal mechanism of reconstructive retrieval. Second, in many cases, traumatic memories are not forgotten at all, but in fact are retained in vivid, relentlessly persistent detail. Severe physical and psychological trauma is
difficult to repress—consciously or unconsciously—despite the fact that forgetting would bring healing and relief. The repeated, intrusive, automatic flashbacks to severely traumatic events constitute a psychological disorder known as post-traumatic stress disorder (PTSD). Sexual assault is known to be a cause of PTSD, as is exposure to combat in war. Known as shell shock in World War I, combat fatigue in World War II, and now PTSD in more recent wars, all refer to the same problem: persistent, unwanted, and disturbing replays of death and destruction, deprivation and despair. Sufferers of PTSD recall the trauma of sexual assault and combat all too easily and frequently.

Both of these problems can be found in the most famous case of repressed memory. At the age of twenty-nine, Eileen Franklin accused her father of being a murderer. Twenty years earlier, her best friend, Susan Nason, had in fact been murdered, and the case had gone unsolved. Eileen had a flashback in adulthood that her father, George, was the perpetrator all those many years ago. Elizabeth Loftus served as an expert witness at George Franklin's trial to provide testimony about the possibility that Eileen's recovered memory was not a consequence of repression but instead reflected a false memory. In her analysis of the case, there were two arguments against the recovered memory theory:

If stress (and, of course, time) cause memory to decay and deteriorate, why did Eileen Franklin's memory come back to her twenty years later in such astonishing, full color detail? If…traumatic events create clear, detailed, and long-lasting memories…, how was Eileen able to push the memory of Susan Nason's murder out of her conscious mind for nearly twenty years?
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Sexual abuse and murder are plausible events, because regrettably they do indeed happen. But what about recovered memories of events that seem highly implausible, more from the realms of fiction and film than from reality? The tabloid press at times reports cases of seemingly sane individuals who recall being abducted by aliens and taken aboard unidentified flying objects (UFOs), being sexually abused during satanic rituals, or witnessing cannibalism of children. From a scientific viewpoint, such reports are difficult to accept as anything other than false because they are so bizarre and implausible. How, then, might they be understood? One plausible explanation is that such
recollections are false memories instilled through a sociocultural mechanism of memory implantation.
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Through repeated suggestion from the information channels of the culture, beliefs about the world take hold. Through what a person reads, watches on television, hears on the radio, and discusses with others who receive the same inputs from the culture, a view of the world can take shape that has very little connection with objective reality. In the laboratory, cognitive psychologists have shown that “exposing people to a set of articles that describe a relatively implausible phenomenon, like witnessing a possession, made people believe that the phenomenon is more plausible, and also made them less confident that they had not experienced the event in childhood.”
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Such memory implantation is perhaps rare but possible if three conditions are met. People must first believe that an event is plausible. Second, they must undergo a process of falsely reconstructing an autobiographical experience that actually happened to them. Third, they must interpret their subsequent thoughts and fantasies related to the event as real memories.