حافظه کاذب برای پیشنهادات: اثر پیچیدگی مفهومی

Relatively little attention has been paid to the potential role that reflecting on the meaning and implications of suggested events (i.e., conceptual elaboration) might play in promoting the creation of false memories. Two experiments assessed whether encouraging repeated conceptual elaboration, would, like perceptual elaboration, increase false memory for suggested events. Results showed that conceptual elaboration of suggested events more often resulted in high confidence false memories (Experiment 1) and false memories that were accompanied by the phenomenal experience of remembering them (Experiment 2) than did surface-level processing. Moreover, conceptual elaboration consistently led to higher rates of false memory than did perceptual elaboration. The false memory effects that resulted from conceptual elaboration were highly dependent on the organization of the postevent interview questions, such that conceptual elaboration only increased false memory beyond surface-level processing when participants evaluated both true and suggested information in relation to the same theme or dimension.

Our memories for specific life events are influenced by the related events that follow them. We discuss event memories with others (Marsh, Tversky, & Hutson, 2005), reflect and ruminate about them, and sometimes reinterpret or reappraise them from a different perspective. These postevent experiences (both internal and external) have the potential to enhance memory, by, for example, preserving and reinforcing accurate elements of the original experience (see, e.g., Bergman and Roediger (1999), for a discussion). However, they also have the potential to contaminate memory with falsehoods and distortions. One well-studied example of memory errors caused by postevent experiences is the false memories that can result from suggestive forensic or therapeutic interviews. Many studies have documented that misleading suggestions provided by an interviewer can result in confidently held recollections of having witnessed fictitious items and even entire fictitious autobiographical events (see, e.g., Loftus, 2003 and Zaragoza et al., 2007, for recent reviews). Although mere exposure to suggestive interviews can lead to false memory development, reflectively elaborating on misleading suggestions in ways that make the memories for suggested information more similar to memories of actually witnessed events can increase both the incidence and magnitude of the resulting false memory effects (e.g., Drivdahl et al., 2009 and Zaragoza et al., 2007). By reflective elaboration we mean any post-perceptual cognitive processing that embellishes the representation in some way. Such reflective elaboration can occur during the initial encoding episode or at later points in time, when thinking about, reviewing (e.g., Lane, Mather, Villa, & Morita, 2001), or reevaluating a prior event. Evidence that reflective elaboration can contribute to false memory development comes from research on the role of imagery as a catalyst to false memory creation. Many studies have shown that encouraging participants to imagine fictitious events can increase false memory development, even when the imagined events are rather bizarre (such as proposing marriage to a Pepsi machine, see, e.g., Seamon et al., 2006 and Thomas and Loftus, 2002). Moreover, repeatedly imagining how things might have happened can further increase false memory for fictitious events (see also, e.g., Goff and Roediger, 1998 and Suengas and Johnson, 1988), and even for entire autobiographical events (e.g., Ceci et al., 1994, Hyman and Pentland, 1996 and Loftus and Pickrell, 1995). Control over exactly what participants imagine (and how) is somewhat limited in these studies, but in general, the focus is on encouraging percept-like images that contain sensory and spatio-temporal details. Instructions often include encouragement to imagine specific details (e.g., “include familiar places, people, and things in the imagined event”, Garry, Manning, Loftus, & Sherman, 1996, p. 210), and both the language of the instructions (e.g., “picture the event”, “you will answer some questions about your image”, Garry et al., 1996, p. 210) and intermittent prompts (e.g., “…describe the image in detail…what the objects, people, and locations looked like”, Hyman & Pentland, 1996, p. 106) often encourage focusing on sensory and spatio-temporal details in particular. The assumption, even if implicit, is that false memories for events are most likely to occur because of confusion about the source of percept-like qualities, such as perceptual and spatio-temporal details. Indeed, more direct evidence that mentally elaborating on the sensory/perceptual characteristics of suggested events increases false memories comes from studies that have asked participants questions specifically about the sensory/perceptual aspects of the suggested or imagined events rather than simply asking participants to imagine them more generally (see, e.g., Drivdahl and Zaragoza, 2001 and Thomas et al., 2003; see also Lane & Zaragoza, 2007). From the perspective of the source monitoring framework (SMF, Johnson et al., 1993 and Lindsay, 2008) the finding that visual imagery is a catalyst to false memory creation is perfectly understandable. According to the SMF, memory representations do not have labels or tags that specify their sources; rather, mental events are attributed to particular sources on the basis of their qualitative and quantitative characteristics. The more that the thoughts and images that come to mind have characteristics of an actually witnessed event, the more likely they are to be experienced as a memory of an actually-experienced event. Thus, imagining perceptual aspects of suggested events often promotes the development of false memories because such imagery induces participants to create a representation of the fictitious event that is rich in vivid sensory/perceptual and contextual details, characteristics that render it similar to, and hence confusable with, a memory for a “real” event (e.g., Johnson et al., 1993 and Suengas and Johnson, 1988; see also, Johnson, Raye, Mitchell, and Ankudowich (in press), for a recent review and discussion of neuroimaging evidence). In addition, during reflection, perceptual details can be “borrowed” or “imported” from similar real events and become associated with the false event thereby making it seem more veridical (e.g., Henkel et al., 2000, Lampinen et al., 2005 and Lyle and Johnson, 2006). Of course, regardless of where the details originate, it is only when erroneous information is taken as evidence of a real memory that a source memory error occurs ( Johnson and Raye, 2000, Johnson et al., 1993, Lindsay, 2008 and Mitchell and Johnson, 2000). Much less attention has been paid to the potential role that conceptual or evaluative reflective processes might have in false memory development in this context (although see Drivdahl et al. (2009), for an exception). However, imagining fictitious events involves more than simply creating a perceptually detailed representation. Imagining how a fictitious event might have transpired also likely involves more abstract sorts of reasoning about the meaning and implications of the fictitious event, and the creation of a plausible scenario that fits with other information in memory. This sort of meaningful elaborative processing may serve to establish stronger and more numerous connections between the suggested fictitious information and other related information in memory, and thereby promote the development of a false memory. In sum, it seems likely that false information that is well-embedded in a coherent network of true memories and knowledge is especially likely to be confused for “real” memories (Johnson, Foley, Suengas, & Raye, 1988). If this is the case, it is possible that reflectively elaborating on the meaning and implications of fictitious events might be an especially potent path to false memory. The goal of the present study was to assess whether repeatedly elaborating on the meaning and implications of suggested events (hereafter referred to as conceptual elaboration), would, like repeated perceptual elaboration (e.g., Drivdahl & Zaragoza, 2001), increase false memory for having witnessed suggested fictitious events. To this end, a modification of the repeated eyewitness suggestibility paradigm was used in which participants were asked questions that encouraged either perceptual or conceptual elaboration of misleading suggestions (e.g., the suggestion that the thief had a gun, when in fact he had no weapon). Participants in a Conceptual Elaboration Group were asked questions that encouraged them to think about the meaning and implications of suggested events (e.g., they were asked how incriminating a jury would find it that the thief had a gun). Participants in a Perceptual Elaboration Group were asked questions that encouraged them to reflect on the visuo/spatial characteristics of the suggested item (e.g., Was the gun tucked in the front or back of the thief’s jeans?). And, because previous studies have shown that false memory for suggested items increases as a function of number of exposures to the misleading suggestion even without prompts to elaborate ( Mitchell and Zaragoza, 1996, Mitchell and Zaragoza, 2001 and Zaragoza and Mitchell, 1996), participants in a No Elaboration Group read the misleading suggestions but did not elaborate on them further. To minimize spontaneous perceptual and conceptual elaboration in this group, they answered follow-up questions that focused on superficial aspects of the misleading suggestion, such as its rhyming characteristics (e.g., what word in this sentence rhymes with “sun”). We note that our use of the terms “conceptual elaboration”, “perceptual elaboration”, and “no elaboration” does not imply that the elaboration carried out in each condition was “process pure”. To the contrary, we assume that all attempts to answer questions about a previously experienced meaningful event will involve reflecting on both the perceptual and meaningful aspects of the event at least to some minimal extent. This is because the perceptual and conceptual dimensions of our experiences cannot be segregated from each other entirely, and all attempts to retrieve a past experience will involve some meaningful processing. Hence, the condition labels refer to the type of reflective elaboration emphasized by the postevent questions in those groups; they are intended as relative terms. As such, we assume primarily meaningful elaboration in the Conceptual Elaboration group, primarily sensory/perceptual elaboration in the Perceptual Elaboration group, and minimal elaboration of either type in the No Elaboration group. Consistent with prior research (e.g., Drivdahl & Zaragoza, 2001), we predicted that reflectively elaborating on the sensory/perceptual aspects of suggested events will increase false memory, such that participants in the Perceptual Elaboration group would be more likely to misattribute the suggested events to the video than those in the No Elaboration group (although the present study employed an immediate test and Drivdahl and Zaragoza (2001) assessed false memory after a 1 week delay). The question of primary interest in this study is whether conceptual elaboration also increases false memory for suggested events. If reflectively elaborating on the meaning and implications of suggested events increases false memory development, participants in the Conceptual Elaboration group also should be more likely to incorrectly claim they remember witnessing the suggested events in the video than participants in the No Elaboration group. More important, inclusion of both a conceptual elaboration and perceptual elaboration condition in the same study allowed us to compare the relative potency of encouraging perceptual vs. conceptual elaboration in promoting false memory.