Imagination inflation: Imagining a childhood event inflates confidence that it occurred
by Elizabeth Loftus
Page 5
Source: http://faculty.washington.edu/eloftus/Articles/Imagine.htm
Discussion
The major result from this experiment is that imagining a self-reported counterfactual event increased confidence that the event did happen. This result complements earlier findings on the power of imagination to increase people's subjective sense of the probability that a future event will occur (see, e.g.. Sherman et al., 1985). Why should imagination influence reports of both future and past events in a similar way? On the face of it, future events and past events do not seem to have much in common. After all, future events are obviously not subject to memory reconstruction (as judged against objective, historical truth), but past events are. For instance, witnessed events are often reported inaccurately (Belli. 1989); more to the point, personal experiences are also subject to various memory distortions (Loftus, 1993). But Johnson and Sherman (1990) argued for less simplistic categories than mere past, present, and future. In their view, both past and future are constructions of the present. The present constantly flows into the past, so the past is always changing. and the future is always being constrained by this changing past. J.1. Gibson (1977/1986) made a similar point when he challenged psychologists to find the place where the present stops and the past takes over. That confidence promoting effects are found for both future and past events suggests that the timeline is not necessarily so neatly carved up into past. present, and future.
Imagination did not have a systematic effect on events that were initially judged to have happened. Of course, the mental activity involved in imagining an actual past event is probably very different from the mental activity involved when one imagines something that did not happen. In other words, an instruction to imagine an event that did not happen may lead people to create an alternate reality, but an instruction to imagine an event that did happen may lead them simply to recall the past event. Thus the mental processes involved when people imagine the real versus the unreal past may be quite different.
In addition to the finding that the act of imagination promotes greater likelihood estimates, there was also a slight tendency for the repeating of an item to produce higher scores. For example, being asked if you had ever broken a window with your hand, then being asked again 2 weeks later, may lead to a small increase in likelihood scores--even without any intervening imagination. Of course, this increase might be nothing more than regression to the mean, but in other domains an analogous "repetition" effect has been found. For example, Arkes and colleagues Arkes, Boehm. & Xu, 1991; Arkes, Hackett, & Boehm, 1989) have shown that validity ratings of true and false statements of fact that have been repeated are greater than validity ratings of unrepeated statements. Even with repeated tests, the largest gains in validity occur between the first and second tests.
Why should there be any gain at all in validity? Subjects do not have access to new, supporting information; they simply read the propositions again. One explanation that Arkes and his colleagues have offered for the repetition effect is that subjects tend to rely on familiarity as one measure of validity, even when the facts are constant. In other words, truth is inferred on the basis of what might be an easier cognitive route: It may be easier to judge the familiarity of content than it is to judge the content itself. In the context of imagination inflation, then, when subjects read an event in the second LEI, they may take the familiarity of the item to mean that it happened. Of course, such a mechanism is a classic case of source confusion, and it is worth repeating (if only to increase the validity of our argument) that source confusion is one of the explanations for the effects seen in the imagine the future literature (Koehler, 1991). This entire line of reasoning is similar to that in arguments made about the venerable "sleeper effect" (Pratkanis, Greenwald, Leippe, & Baumgardner, 1988), in which content and source eventually become dissociated, and a proposition that would immediately have been judged invalid (because its source was suspect) is now judged as true.
In short, if the work of Arkes et al. (1989, 1991) shows that asking twice about a purported fact results in higher validity ratings, it seems plausible that asking twice about a purported event may result in higher likelihood estimates. Perhaps pondering whether or not an event occurred involves a subset of the same strategies that are involved in imagination. On the other hand, we should exercise caution in going too tar afield with a discussion of repetition effects; the effects observed In the present experiment might actually be explained by regression to the mean, and research is needed to specifically investigate the possibility of a repetition effect for past events.
Of course, there are other explanations for the present results. One account for at least some of these data is what we will call the reinterpretation hypothesis. It supposes that a given item is interpreted more broadly on the LEI posttest than it is on the pretest. In other words, the item expands to accommodate the event. The reinterpretation mechanism is entirely plausible, and it is not clear that it would generally work to produce imagination inflation. Reinterpretation could easily lead to imagination deflation. To see why, consider that the imagination procedure leads subjects to imagine a specific, complex scenario in which they are the protagonists. Thus, the "imagined " subjects should have more constrained item interpretations, and the "not imagined" subjects should have a greater tendency to reinterpret items more broadly, permitting more instances of events that fit the item; such a pattern would work against the imagination inflation effect. In short, a reinterpretation mechanism might inflate confidence in some item and event combinations, and deflate confidence in others.
Another explanation for the increased confidence we observed after imagination involves the concept of hypermnesia. Hypermnesia is the tendency toward increased recall over successive tests. In a typical hypermnesia experiment, subjects study word lists and then take several successive tests. Recall performance often improves steadily over repeated testing (e.g.. Roediger & Payne, 1985). Under the hypermnesia explanation, the design of the present experiment merely promotes the increasingly accurate recall of genuinely experienced events. For instance, the first LEI test is the first occasion to think about an event, and it thus produces the least accurate memory. The second test produces more accurate memory than the first, and the act of imagination is yet another chance to think about the target event. Subjects who Imagine an event are given an additional opportunity to think about it, which explains imagination inflation. The newly remembered event could conceivably be one that fits the LEI item well, or one that fits somewhat.
We cannot rule out the hypermnesia possibility given the data we collected here. Perhaps imagination inflation is sometimes due to new genuine memories, and sometime to enhanced confidence about false memories. This is a question worthy of further research with more probative methods. Before leaving the topic of hypermnesia, however, we note two points about how the present study differs considerably from the typical hypermnesia study. The first difference is on what is being measured. The relatively neat content of hypermnesiac memories (see. e.g., Roediger & Payne. 1985) may not generalize to the messy complexity of real life memories (see. e.g., Neisser, 1986). The second difference is in how these memories are measured. Hypermnesia is found with recall tests, but not with recognition tests (Payne & Roediger, 1987). However, we used a test that cannot be categorized neatly as either recall or recognition. Subjects were asked to indicate which of 40 possible childhood experiences had occurred. The items did not describe very simple experiences. Instead. they described events of some complexity, in that multiple idea units were in all of the critical items (except for the "Haircut event"; see Table 1). For example, subjects were not asked if they had ever found any amount of money anywhere at any time in their lives; they were asked if they had ever found a $10 bill in a parking lot before they were 10 years old.
In the present research, we do not know if imagining the event itself might cause imagination inflation. or if one must be the agent in the event. Source confusions might be increased (and imagination inflation be most pronounced) when subjects imagine themselves, say, finding a $10 bill in a parking lot, but not if they imagine Bill Clinton finding the same $10 bill. Imagining oneself should create more kinds of weak information (e.g., weak kinesthetic and haptic information) that could later increase familiarity. We also do not know which subjects in which events--if any--recognized that an LEI item asked about an event that had been imagined several minutes earlier. Future research is needed to ascertain whether subjects are drawing this link, and not showing imagination inflation when they do. Even if subjects do make a conscious link between the LEI item and the imagination exercise, we might still see an imagination effect. For instance, these subjects might not think that all of the familiarity associated with the asked about event was due to the earlier act of imagination, or they might think that the event is familiar for reasons in addition to imagining it. More to the point, if some subjects were indeed meeting the demand of the experiment by deliberately inflating their scores, we should have seen increased confidence among those subjects who originally were confident that a given event had happened. Instead, we saw no particular pattern in that category.
These results suggest appropriate restraint in situations in which imagination is used as an aid in searching for or shoring up presumably lost memories. When the police repeatedly ask a suspect to imagine his possible role in a murder he does not remember, or when a mental health processional repeatedly encourages a client to imagine an abusive childhood event, these imagination activities may unknowingly promote a greater belief that particular episodes occurred. The search for fact may create a fiction. Such is the power of imagination, long ago recognized by Keats (1817, cited in Bartlett. 1992, p. 417), who said, "The Imagination may be compared to Adam's dream--he awoke and found it truth."
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