Carol L. Raye

Phenomenal characteristics of memories for perceived and imagined autobiographical events.

Two studies explored potential bases for reality monitoring (Johnson & Raye, 1981) of naturally occurring autobiographical events. In Study 1, subjects rated phenomenal characteristics of recent and childhood memories. Compared with imagined events, perceived events were given higher ratings on several characteristics, including perceptual information, contextual information, and supporting memories. This was especially true for recent memories. In Study 2, subjects described how they knew autobiographical events had (or had not) happened. For perceived events, subjects were likely to mention perceptual and contextual details of the memory and to refer to other supporting memories. For imagined events, subjects were likely to engage in reasoning based on prior knowledge. The results are consistent with the idea that reality monitoring draws on differences in qualitative characteristics of memories for perceived and imagined events (Johnson & Raye, 1981) and augment findings from more controlled laboratory studies of complex events (Johnson & Suengas, in press; Suengas & Johnson, 1988).

Separable Neural Components in the Processing of Black and White Faces

In a study of the neural components of automatic and controlled social evaluation, White participants viewed Black and White faces during event-related functional magnetic resonance imaging. When the faces were presented for 30 ms, activation in the amygdala—a brain region associated with emotion—was greater for Black than for White faces. When the faces were presented for 525 ms, this difference was significantly reduced, and regions of frontal cortex associated with control and regulation showed greater activation for Black than White faces. Furthermore, greater race bias on an indirect behavioral measure was correlated with greater difference in amygdala activation between Black and White faces, and frontal activity predicted a reduction in Black-White differences in amygdala activity from the 30-ms to the 525-ms condition. These results provide evidence for neural distinctions between automatic and more controlled processing of social groups, and suggest that controlled processes may modulate automatic evaluation.

fMRI evidence of age-related hippocampal dysfunction in feature binding in working memory.

Richly detailed memories for particular events depend on processes that bind individual features of experience together. Previous cognitive behavioral research indicates that older adults have more difficulty than young adults in conditions requiring feature binding. We used functional magnetic resonance imaging (fMRI) during a working memory task to identify neural substrates of this age-related deficit in feature binding. For young, but not older, adults there was greater activation in left anterior hippocampus on combination trials (remember objects together with their locations) than on trials in which participants were told to remember only which objects or only which locations occurred. The results provide neuroimaging evidence for an age-related hippocampal dysfunction in feature binding in working memory.

Implicit and Explicit Evaluation: fMRI Correlates of Valence, Emotional Intensity, and Control in the Processing of Attitudes

Previous work suggests that explicit and implicit evaluations (goodbad) involve somewhat different neural circuits that process different dimensions such as valence, emotional intensity, and complexity. To better understand these differences, we used functional magnetic resonance imaging to identify brain regions that respond differentially to such dimensions depending on whether or not an explicit evaluation is required. Participants made either goodbad judgments (evaluative) or abstractconcrete judgments (not explicitly evaluative) about socially relevant concepts (e.g., murder, happiness, abortion, welfare). After scanning, participants rated the concepts for goodness, badness, emotional intensity, and how much they tried to control their evaluation of the concept. Amygdala activation correlated with emotional intensity and right insula activation correlated with valence in both tasks, indicating that these aspects of stimuli were processed by these areas regardless of intention. In contrast, for the explicitly evaluative goodbad task only, activity in the anterior cingulate, frontal pole, and lateral areas of the orbital frontal cortex correlated with ratings of control, which in turn were correlated with a measure of ambivalence. These results highlight that evaluations are the consequence of complex circuits that vary depending on task demands.

Cognitive Operations and Decision Bias in Reality Monitoring

In each of the three experiments, a reality monitoring task required subjects to discriminate between words they generated and words presented by an experimenter. Each of the experiments included a manipulation designed to affect the amount of external control over what the subject generated, with the expectation that the more a response is determined by external cues, the less the memory will include information about cognitive operations that took place when the memory was established. In general, increasing cognitive operations increased accuracy of reality monitoring. In addition, when subjects falsely recognized new items as old, they were much more likely to attribute the items to external sources than to internal sources. These findings were discussed primarily in terms of the role that cognitive operations preserved in memory may play in identifying the origin of information in memory. A comparison of memory for the occurrence of experimenterpresented and subject-generated items, regardless of correct identification of origin, extended the generation effect found by Slamecka and Graf in 1978 to information only covertly generated by the subject (Experiment 1), and to retention intervals as long as 10 days (Experiment 2). The results of Experiment 3 suggested that the generation effect may not necessarily appear in situations in which what is generated is essentially a meaningful response to what is perceived.

Aging and reflective processes of working memory: binding and test load deficits.

It was hypothesized that age-related deficits in episodic memory for feature combinations (e.g., B. L. Chalfonte & M. K. Johnson, 1996) signal, in part, decrements in the efficacy of reflective component processes (e.g., M. K. Johnson, 1992) that support the short-term maintenance and manipulation of information during encoding (e.g., F. 1. M. Craik. R. G. Morris. & M. L. Gick, 1990; T. A. Salthouse, 1990). Consistent with this, age-related binding deficits in a working memory task were found in 2 experiments. Evidence for an age-related test load deficit was also found: Older adults had greater difficulty than young adults when tested on 2 features rather than 1, even when binding was not required. Thus, disruption of source memory in older adults may involve deficits in both encoding processes (binding deficits) and monitoring processes (difficulty accessing multiple features, evaluating them, or both).

Age-related Changes in Confusion between Memories for Thoughts and Memories for Speech.

The present experiments compared peoples abilities to make decisions about the origin of their memories. Experiment 1 demonstrated that 6-year-olds were as good as 17-year-olds in discriminating memories originating from what they said earlier (self-generations) from memories of what another person said earlier (external presentations). However, in both experiments 1 and 2, 6-year-olds were not as good at discriminating what they had said earlier from what they had only thought. The possibility that younger children simply have more difficulty distinguishing between memories originating from the same class, internal or external, was ruled out because 6-year-olds performed as well as 9-year-olds when differentiating between memories from 2 external sources (experiment 2). Nor could their difficulty be attributed to a general problem in distinguishing memories for their thoughts from any other class of memories because they were at no disadvantage in discriminating their earlier thoughts (words they imagined themselves saying) from words someone else said (experiment 2). Our findings suggest that some distinctions, self versus other, emerge as cues in memory sooner than other distinctions, thoughts versus actions.

Refreshing: a minimal executive function.

Executive functions include processes by which important information (e.g., words, objects, task goals, contextual information) generated via perception or thought can be foregrounded and thereby influence current and subsequent processing. One simple executive process that has the effect of foregrounding information is refreshing--thinking briefly of a just-activated representation. Previous studies (e.g., Johnson et al., 2005) identified refresh-related activity in several areas of left prefrontal cortex (PFC). To further specify the respective functions of these PFC areas in refreshing, in Experiment 1, healthy young adult participants were randomly cued to think of a just previously seen word (refresh) or cued to press a button (act). Compared to simply reading a word, refresh and act conditions resulted in similar levels of activity in left lateral anterior PFC but only refreshing resulted in greater activity in left dorsolateral PFC. In Experiment 2, refreshing was contrasted with a minimal phonological rehearsal condition. Refreshing was associated with activity in left dorsolateral PFC and rehearsing with activity in left ventrolateral PFC. In both experiments, correlations of activity among brain areas suggest different functional connectivity for these processes. Together, these findings provide evidence that (1) left lateral anterior PFC is associated with initiating a non-automatic process, (2) left dorsolateral PFC is associated with foregrounding a specific mental representation, and (3) refreshing and rehearsing are neurally distinguishable processes.

Emotional Arousal Can Impair Feature Binding in Working Memory

To investigate whether emotional arousal affects memorial feature binding, we had participants complete a short-term source-monitoring taskremembering the locations of four different pictures over a brief delay. On each trial, the four pictures were all either high arousal, medium arousal, or low arousal. Memory for picture-location conjunctions decreased as arousal increased. In addition, source memory for the location of negative pictures was worse among participants with higher depression scores. Two subsequent functional magnetic resonance imaging experiments showed that relative to low-arousal trials, high- and medium-arousal trials resulted in greater activity in areas associated with visual processing (fusiform gyrus, middle temporal gyrus/middle occipital gyrus, lingual gyrus) and less activity in superior precentral gyrus and the precentral-superior temporal intersect. These findings suggest that arousal (and perhaps negative valence for depressed people) recruits attention to items thereby disrupting working memory processes that help bind features together.

Using fMRI to investigate a component process of reflection: Prefrontal correlates of refreshing a just-activated representation

Using fMRI, we investigated the functional organization of prefrontal cortex (PFC) as participants briefly thought of a single just-experienced item (i.e., refreshed an active representation). The results of six studies, and a meta-analysis including previous studies, identified regions in left dorsolateral, anterior, and ventrolateral PFC associated in varying degrees with refreshing different types of information (visual and auditory words, drawings, patterns, people, places, or locations). In addition, activity increased in anterior cingulate with selection demands and in orbitofrontal cortex when a nonselected item was emotionally salient, consistent with a role for these areas in cognitive control (e.g., overcoming “mental rubbernecking”). We also found evidence that presenting emotional information disrupted an anterior component of the refresh circuit. We suggest that refreshing accounts for some neural activity observed in more complex tasks, such as working memory, long-term memory, and problem solving, and that its disruption (e.g., from aging or emotion) could have a broad impact.