Source-Specifying Information Affects Imagination Inflation

Abstract

Imagination inflation is the increase in subjects' confidence that fictitious childhood event really happened after they merely imagined it (Garry, Manning, Loftus, & Sherman, 1996). Two explanations have been proposed to account for this increase in confidence. In a familiarity explanation, the act of imagining the fictitious events makes them more fluent, which subjects interpret as a feeling of familiarity because the event really happened. In a source confusion explanation, the act of imagining generates weak perceptual fragments, and subjects confuse these generated fragments with fragments of their real memories. However, recent research suggests that familiarity and source confusion share many overlapping features. Moreover, research suggests that the source confusion explanation does not provide a good account of imagination inflation. Thus, this thesis focused on expanding the fluency-based familiarity account of imagination inflation. This "fluency monitoring" explanation is proposed to incorporate two steps. First, the processing fluency of the target events needs to increase. Second, people need to experience a fluency confusion and misattribute this increased fluency to their childhoods. To investigate this fluency account of imagination inflation, the level of source specifying information (SSI) subjects generated was manipulated. It was predicted that when subjects were able to detect the SSI they would not show imagination inflation because they would be able to use it to attribute the increased fluency of the imagined events to the imagination exercise. Thus, the level of SSI was manipulated in the series of experiments described in this thesis from a low level (Experiment r) to a higher level (Experiment 4). In Experiment 1, SSI was manipulated in the form of the perspective subjects used when they imagined the target events. In Experiment 2, another level of SSI was added to the perspective manipulation, in the form of a plausibility questionnaire. That is, subjects had one (perspective or plausibility only) or two sources of SSI (perspective and plausibility). Experiment 3 was conducted to investigate how increasing the SSI decreases imagination inflation. Experiment 4 investigated whether subjects could use source monitoring cues as SSI. Overall, the results from Experiments 1 to 4 provided support for the fluency monitoring account of imagination inflation. Thus, the focus of Experiment 5 changed slightly. Instead of investigating the effect of the amount of SSI, the source of the false information was examined. Subjects either imagined a false childhood haircut; were told their parents provided information about the haircut; both imagined and were told about the haircut, or were in the control condition. Taken together, the findings from all five experiments support the fluency monitoring account of imagination inflation. The account is applied to other areas of research, and future research is suggested. Both the practical and theoretical implications of this series of experiments are discussed.