Imagination Inflation

The finding that an external suggestion can lead to the construction of false childhood memories helps us understand the process by which false memories arise. It is natural to wonder whether this research is applicable in real situations such as being interrogated by law officers or in psychotherapy. Although strong suggestion may not routinely occur in police questioning or therapy, suggestion in the form of an imagination exercise sometimes does. For instance, when trying to obtain a confession law officers may ask a suspect to imagine having participated in a criminal act. Some mental health professionals encourage patients to imagine childhood events as a way of recovering supposedly hidden memories.

Surveys of clinical psychologists reveal that 11 percent instruct their clients to "let the imagination run wild" and 22 percent tell their clients to "give free rein to the imagination." Therapist Wendy Maltz, author of a popular book on childhood sexual abuse, advocates telling the patient: "Spend time imagining that you were sexually abused, without worrying about accuracy, proving anything, or having your ideas make sense. . . . Ask yourself. . .these questions: What time of day is it? Where are you? Indoors or outdoors? What kind of things are happening? Is there one or more person with you?" Maltz further recommends that therapists continue to ask questions such as: "Who would have been likely perpetrators? When were you most vulnerable to sexual abuse in your life?"

The increasing use of such imagination exercises led me and several colleagues to wonder about their consequences. What happens when people imagine childhood events that did not happen to them? Does imagining a childhood event increase confidence that it occurred? To explore this, we designed a three-stage procedure. We first asked individuals to indicate the likelihood that certain events happened to them during their childhood. The list contains 40 events, each rated on a scale ranging from "definitely did not happen" to "definitely did happen." Two weeks later, we asked the participants to imagine that they had experienced some of these events. Different subjects were asked to imagine different events. Some time later the participants again were asked to respond to the original list of 40 childhood events, indicating how likely it was that these events actually happened to them.

Consider one of the imagination exercises. The participants are told to imagine playing inside at home after school, hearing a strange noise outside, running toward the window, tripping, falling, reaching out and breaking the window with their hand. In addition, we asked participants questions such as: "What did you trip on?" "How did you feel?"

In one study, 24 percent of the participants who imagined the broken-window scenario later reported an increase in confidence that the event had occurred, whereas only 12 percent of those who were not asked to imagine the event reported an increase in the likelihood that the event had taken place. We found this "imagination inflation" effect in each of the eight events that participants were asked to imagine. A number of possible explanations come to mind. An obvious one is that an act of imagination simply makes the event seem more familiar and that familiarity is mistakenly related to childhood memories rather than to the act of imagination. Such source confusion -- when a person does not remember the source of information -- can be especially acute for the distant events of childhood.

Studies of by Lyn Goff and Henry L. Roediger III of Washington University of recent rather than childhood experiences more directly connect imagined actions to the construction of false memory. During the initial session, the researchers instructed participants to perform the stated action, imagine doing it, or just listen to the statement but do nothing else. The actions were simple ones such as knock on the table, lift the stapler, break the toothpick, cross your fingers, roll your eyes. During a second session, the participants were asked to imagine some of the actions that they had not previously performed. During the final session, they answered questions about what actions they actually performed during the initial session. The investigators found that the more times participants imagined an unperformed action, the more likely they were to remember having performed it.