Cognitive and Brain Mechanisms of True and False Memories and Beliefs

Marcia K. Johnson (Princeton University)

Many, perhaps most, memory distortion reflects failures to identify the sources of mental experience. For example, people sometimes confuse what they inferred or imagined and what actually happened, what they saw or read and what was suggested to them, what one person said and what another said, what they recently heard and what they previously knew, and fiction and fact. Reality monitoring failures are an especially interesting class of memory distortion in which people confuse information derived from perceptual processes and information derived from reflective or self-generated processes. According to the source monitoring framework (e.g., Johnson & Raye, 1981; Johnson, 1991; Johnson, Hashtroudi, & Lindsay, 1993), source confusions arise because activated information is incomplete or ambiguous and because the evaluative processes responsible for attributing such information to sources are imperfect. Both accurate and inaccurate source attributions result from heuristic processes that evaluate a mental experience for various qualities such as amount and type of perceptual, contextual, affective, semantic, and cognitive detail, and from more reflectively complex processes that retrieve additional supporting or disconfirming evidence and evaluate plausibility given general knowledge, schemas, assumptions, and biases. Recent experimental evidence from our lab regarding cognitive mechanisms of source memory and underlying brain structures will be discussed.

Postevent Misinformation Effects

D. Stephen Lindsay (University of Victoria)

Participants asked to remember an event often erroneously report having witnessed details that had in fact merely been mentioned in postevent information. Throughout the mid 1980s debate focused on whether postevent suggestions impair ability to remember what was actually witnessed. In the 1990s, researchers have emphasized the question of whether or not misled individuals have the phenomenological experience of remembering witnessing details that were merely suggested to them. It is clear that many false reports in the standard Loftus paradigm reflect aware uses of postevent information (e.g., the individual thinks, "I don't remember what tool I saw in the event, but I remember that I was later told it was a hammer, so I'll say 'hammer'"). It is also clear, however, that some false reports reflect illusory memories of witnessing suggested details. My talk will review research from my lab exploring the conditions that foster such illusory memories of witnessing, including recent experiments (a) using Jacoby's process-dissociation procedure to estimate aware versus unaware uses of postevent information at test, (b) examining intrusions from postevent information that is versus is not "about" the witnessed event, and (c) exploring suggestion-induced false memories for relatively complex and naturalistic autobiographical events.

The (De)construction of Subjective Experience

Jeffrey P. Toth (Georgia Institute of Technology)

A fluency heuristic has been proposed to underlie feelings of familiarity in recognition memory; all things being equal, items processed more fluently are more likely to be judged "old" regardless of their true episodic status (Whittlesea, 1993). Importantly, however, fluent processing need not support only episodic (context-specific) memory judgments, but can also influence more general judgments concerning world knowledge (Kelley & Lindsay, 1993), personal preferences (Kunst-Wilson & Zajonc, 1980), and other perceptual and interpretive judgments based on subjective experience (Jacoby, Kelley, & Dywan, 1989). What are the 'rules' and operating characteristics by which fluency, derived from prior experience, will have such effects? We examined this question in a series of experiments requiring subjects to make judgments about general word frequency. We found that a single exposure of a word could significantly alter its judged (acontextual) frequency at a later time. However, numerous conditions were also identified in which such alterations of judged frequency did not occur. Possible explanations for the presence and absence of these episodic influences on subjective experience are explored including conscious uses of memory, the availability of an analytic judgment strategy, and the subjects' point of view at the time of judgment. These dimensions may be useful in explaining a variety of reconstructive memory phenomena.

Judgments About Childhood Memories: Remembering Whether We Always
Remembered

J. Don Read (University of Lethbridge)

The claim that traumatic experiences have amnestic effects has been based on survivors' observations that there were periods of time in which they did not well remember the experience(s). In turn, the current availability of information and the respondents' perception that it was previously unavailable has been taken as evidence of both the prior loss and subsequent recovery of memory for some event(s). However, these data derive from retrospective judgments about what was available to recall at a particular time in the past, judgments that are likely to be affected by cognitive heuristics and biases. Our research explores these kinds of judgments for childhood autobiographical events and suggests that memory retrieval activities increase the likelihood that respondents will overestimate the extent of their prior memory impairments.

A Hot/Cool System Analysis of Emotional Memory and the Dynamics of Willpower

Janet Metcalfe (Columbia University)

The relations among stress, learning, and remembering have a puzzling if not paradoxical history, with research from various laboratories indicating enhanced memory under stress, impaired memory under stress, flashbulb memory under stress, and even no change in memory as a function of stress. Two closely linked systems are postulated here: a cool, hippocampally-based, cognitive 'know' system which maintains complex, bound memories of episodes replete with contextual details, and a hot, amygdala-based, emotional 'go' system which processes and remembers unbound, fragmentary emotional trigger stimuli producing conditional fear responses. The cool system is cognitive, emotionally neutral, contemplative, flexible, integrated, coherent, spatio-temporal, slow, episodic, strategic. It is also the seat of self-regulation and self-control. The hot system is the basis of emotionality, fears as well as passions--impulsive and reflexive--initially controlled by innate releasing stimuli (and thus literally under 'stimulus control'), it is fundamental for emotional (classical) conditioning, and undermines efforts at self-control. The balance between the hot and cool systems is determined by stress, developmental level, and the individual's self-regulatory dynamics. The interactions between these systems allow prediction and explanation of stress-related memory findings. We review relevant evidence--from the cellular and neurohormonal level, to the systems and behavioral level--relating this two-system framework to human memory phenomena exhibited under conditions ranging from mild arousal to traumatic stress. If time permits we will extend this framework to account for the findings on goal-directed delay of gratification and willpower.

Lost in Translation: Verbal Overshadowing of Non-Verbal Memories

Jonathan W. Schooler (University of Pittsburgh)

Considerable research has demonstrated that verbalizing non-verbal memories can impair subsequent memory performance. For example, describing a previously seen face can interfere with individuals ability to correctly identify that face in a line up. This talk will review the evidence that this form of memory interference, termed verbal overshadowing, results from a mismatch between the nonverbal perceptual information associated with the original memory and the verbal information associated with the act of verbal retrieval. Three distinct predictions of the modality mismatch assumption will be considered. 1) The generality of verbal overshadowing - If verbalization disrupts the application of nonverbal knowledge, then the effects of verbalization should generalize across domains that rely on nonverbal knowledge. 2) Processing differences - If it is specifically the language component of verbal rehearsal that produces the interference, then the effects of rehearsal on nonverbal stimuli should be shown to specifically depend on whether or not verbal processes are engaged. 3) Expertise differences - If verbalization specifically disrupts the application of nonverbal knowledge then its effect should depend on individuals' relative verbal and nonverbal expertise. Evidence in support of all three of these predictions will be provided.