False Recognition & Retrieval Failure 2

People often falsely recognize items that are similar to previously encountered items. This robust memory error is referred to as gist-based false recognition. A widely held view is that this error occurs because the details fade rapidly from our memory. Contrary to this view, an initial experiment revealed that, following the same encoding conditions that produce high rates of gist-based false recognition, participants overwhelmingly chose the correct target rather than its related foil when given the option to do so. A second experiment showed that this result is due to increased access to stored details provided by reinstatement of the originally encoded photograph, rather than to increased attention to the details. Collectively, these results suggest that details needed for accurate recognition are, to a large extent, still stored in memory and that a critical factor determining whether false recognition will occur is whether these details can be accessed during retrieval. False
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 INTRODUCTION Human memory is not a literal reproduction of the past, like a photograph or film, but rather a constructed representation of past experience that is influenced by a variety of factors related to the originally encoded event, including general knowledge, personal biases, information from other events, and inferences (Bartlett, 1932; Johnson, 1997; Johnson, Hashtroudi, & Lindsay, 1993; Loftus, 1979, 2003; Roediger, 1996; Schacter, Norman, & Koutstaal, 1998). These constructive processes presumably lead to functionally beneficial representations of the past, but they also cause memory to be prone to error (Schacter, 1999, 2001) The mistaken recognition of an item that is similar, but not identical, to a previously encountered item is a ubiquitous and robust memory error referred to as gist-based false recognition (Koutstaal & Schacter, 1997; cf., Reyna & Brainerd, 1995). For instance, people tend to mistakenly recognize a word that is a synonym of a studied word (Anisfeld & Knapp, 1968), an abstract shape that is structurally similar to studied shapes (Koutstaal, Schacter, Verfaellie, Brenner, & Jackson, 1999; Slotnick & Schacter, 2004), or a pictured object that has the same verbal label as a studied item (Koutstaal, 2006). In these cases, people fail to remember the specific details of an event but can remember more abstracted information — the “gist” — such as the superordinate category of an encountered object. One possibility is that these errors occur because the original details have been lost from memory, either because they were not encoded originally or because the memory trace has degraded over time. Then, at retrieval, the system relies on more abstract information to reconstruct the lost details. This line of thinking has been implicit in much of the literature. For instance, in the Constructive Memory Framework put False
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 forward by Schacter et al. (1998), it was proposed that gist-based false recognition results primarily from a failure of pattern separation, a process that occurs during encoding. Thus, according to this proposal, gist-based false recognition occurs in large part because the details were not adequately encoded in the first place. Brainerd and Reyna’s (2002) Fuzzy Trace Theory proposed that verbatim details are forgotten more rapidly than gist information, a combination that contributes to gist-based false recognition (see also Reyna & Brainerd, 1995). However, it is also known that people can store an impressive amount of information, particularly about recently encountered pictures or objects. For example, Standing (1973) demonstrated that people could recognize thousands of experimentally presented pictures. More recently, Brady et al. (2008) had participants study 2,896 pictures of objects shown for 3 s each. In a forced-choice test, participants were asked to make subtle distinctions based on memory: the foil was the same object as the studied item, but in a slightly different state (e.g., a bread box with the loaf of bread inside the box or outside the box). Participants scored 87% correct in this condition, suggesting that people can store a large amount of detailed information about recently encountered objects (see also Konkle, Brady, Alvarez, & Oliva, 2010). These findings present a puzzle. On the one hand, a large body of data on false recognition suggests that the detail stored in episodic memory is limited and that memory relies heavily on constructive processes to compensate for this limitation. On the other hand, the findings concerning highly specific recognition of visual objects suggest that the level of detail stored in episodic memory is far greater than what would have been False
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 expected on the basis of the false recognition findings. Here we attempt to reconcile these seemingly contradictory results. We suggest that, even when rates of false recognition are high, people do retain many details, but do not adequately utilize them at retrieval. In two experiments, we explored the hypothesis that high rates of false recognition occur when people do not attend to or do not retrieve the relevant perceptual details. To this end, we developed an experimental paradigm that encouraged participants to focus on the relevant perceptual details. EXPERIMENT 1 Method Rationale and Design The conditions of the memory test are depicted in Figure
1. On each trial, the participant was presented with three pictures. Two of the pictures were related to one another because they were both exemplars of the same category and shared a common verbal label. It is important to note that the conditions did not differ systematically in terms of their perceptual presentation; they differed only in terms of the content of the participant’s memory. The participant’s task was to select one of the items as studied or reject all three items as new (“all new”). In the baseline target condition, one of the pictures was a target (studied item) and the other two items were not systematically related to any of the studied items. In the baseline lure condition, all three items were not systematically related to any of the studied items and the correct response was “all new”. In the single related item condition, one of the pictures was related to a studied item. The other two items were not systematically related to any of the studied items. The correct False
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 response was “all new”, but we anticipated that participants would falsely recognize the related item with high frequency, reflecting a standard gist-based false recognition effect. In the target and related item condition, the target was presented adjacent to the related item. The third item was not systematically related to any of the studied items. In this condition, the nature of the discrimination required was made explicit to the participant. Both the target and the related lure were likely to seem familiar, thus requiring that the participant systematically compared the target and related lure and identified features that distinguished them. If gist-based false recognition occurs because people fail to attend to or retrieve relevant perceptual details still stored in memory, then false recognition rates should be substantially reduced in this condition. Participants 32 college students (15 male, ages 18-29, mean 22) from the Boston metropolitan area served as participants and were paid $70 (participants were scanned with functional MRI during the experiment; the imaging data will be presented in a separate report). Candidates were excluded for participation that did not meet standard MRI safety criteria, required glasses to see normally, had strabismus or a history of eye surgery, or that were left handed. All participants provided informed consent as approved by the Institutional Review Board at Harvard University. Nine participants were replaced: 4 for poor performance (hits minus false alarms less than .30); 3 for eye tracking problems; 2 for anatomical abnormalities. Stimulus Materials 384 pairs of object photographs or detailed, colored drawings served as stimuli (Koutstaal, 2006; Koutstaal, et al., 2001). The items within a pair were related to each False
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 other because they were both exemplars of the same category and shared a common verbal label (e.g., wrench, dog, tree). However, the two pictures were perceptually distinct exemplars of the category and, at a minimum, differed in terms of color or orientation. Stimuli were fully counterbalanced (Supplementary Methods). Procedure Participants were told that their memory would be tested later and were presented with 144 objects (500 ms duration, 1500 ms ISI) and indicated whether the pictured object could fit into a 13 inch box in the real world by a button press. A box measuring approximately 13 inches was presented. The participant was given a self-paced break halfway through the study session. Then the participant was placed in an MRI scanner. The occurrence of similar foils was clearly explained to the participant. The test was divided into four blocks; each began with 15 s of fixation and ended with 10 s of fixation and contained 12 trials of each condition. Each trial lasted 5 s. With the constraint that the two related items were next to each other, there were four possible arrangements of the pictures; each occurred equally often within each block. 24 fixation trials, also lasting 5 s, were randomly intermixed within each block. Results Accuracy The accuracy data are shown in Figure
2 (reaction times are reported in Supplementary
Table
1). Within the baseline target condition, the hit rate was reasonably high (.76, SEM = .02, green bar). Within the baseline foil condition, the correct rejection rate was reasonably high (.69, SEM = .03, blue bar). Therefore, participants performed the task well. False
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