The neural correlates of gist-based true and false recognition

When information is thematically related to previously studied information, gist-based processes contribute to false recognition. Using functional MRI, we examined the neural correlates of gist-based recognition as a function of increasing numbers of studied exemplars. Sixteen participants incidentally encoded small, medium, and large sets of pictures, and we compared the neural response at recognition using parametric modulation analyses. For hits, regions in middle occipital, middle temporal, and posterior parietal cortex linearly modulated their activity according to the number of related encoded items. For false alarms, visual, parietal, and hippocampal regions were modulated as a function of the encoded set size. The present results are consistent with prior work in that the neural regions supporting veridical memory also contribute to false memory for related information. The results also reveal that these regions respond to the degree of relatedness among similar items, and implicate perceptual and constructive processes in gist-based false memory.Psycholog

Aging, self-referencing, and medial prefrontal cortex

The lateral prefrontal cortex undergoes both structural and functional changes with healthy aging. In contrast, there is little structural change in the medial prefrontal cortex, but relatively little is known about the functional changes to this region with age. Using an event-related fMRI design, we investigated the response of medial prefrontal cortex during self-referencing in order to compare age groups on a task that young and elderly perform similarly and that is known to actively engage the region in young adults. Nineteen young (M age 23) and seventeen elderly (M age 72) judged whether adjectives described themselves, another person, or were presented in upper case. We assessed the overlap in activations between young and elderly for the self-reference effect (self vs. other person), and found that both groups engage medial prefrontal cortex and mid-cingulate during self-referencing. The only cerebral differences between the groups in self versus other personality assessment were found in somatosensory and motorrelated areas. In contrast, age-related modulations were found in the cerebral network recruited for emotional valence processing. Elderly (but not young) showed increased activity in the dorsal prefrontal cortex for positive relative to negative items, which could reflect an increase in controlled processing of positive information for elderly adults. Aging is associated with declines in cognitive performance in a number of domains. Recent neuroimaging data suggest that changes to the prefrontal cortex may contribute to impaired memory and cognition with age. Structurally, the prefrontal cortex shows pronounced shrinkage with age (Raz, 2000). Functionally, the engagement of frontal mnemonic processes appears to differ in young and elderly adults: Older adults show reduced activation of left inferior fronta

Effects of aging and encoding instructions on emotion-induced memory tradeoffs

The effects of emotion on memory are often described in terms of trade-offs: People often remember central, emotional information at the expense of background details. The present experiment examined the effects of aging and encoding instructions on participants' ability to remember the details of central emotional objects and the backgrounds on which those objects were placed. When young and older adults passively viewed scenes, both age groups showed strong emotion-induced trade-offs. They were able to remember the visual details as well as the general theme of the emotional object, but they had difficulties remembering the visual specifics of the scene background. Age differences emerged, however, when participants were given encoding instructions that emphasized elaborative encoding of the entire scene. With these instructions, young adults overcame the trade-offs (i.e., they no longer showed impairing effects of emotion), whereas older adults continued to show good memory for the emotional object but poor memory for its background. These results suggest that aging impairs the ability to flexibly disengage attention from the negative arousing elements of scenes, preventing the successful encoding of nonemotional aspects of the environment

Reduction of the self-reference effect in younger and older adults

Relating information to the self improves memory. However, this self-reference effect (SRE) is typically studied through explicit self-judgments on individual trials. The current study assessed whether a self-referential mode of thought, induced through a writing task, also induced an SRE on a later task. The study also tested the effects of aging on the SRE, given that a long-lasting mnemonic strategy may be especially relevant for this group. Ninety-two younger adults and 60 older adults were assigned to different writing conditions and then completed an unrelated SRE task. Across younger and older adults, the classic SRE effect was observed in the narrative writing condition, reduced in the semantic self-reference condition, and further reduced in the episodic self-reference condition. These results support the induction of a self-referential mode of thought, but this mode does not enhance memory. The classic SRE effect can be reduced after thinking about the self by reflecting on autobiographical memories. Results argue for a single shared self-referential mechanism that can be accessed through self-focused writing or the classic SRE task

STOP SHOUTING AT ME: The Influence of Case and Self-Referencing on Explicit and Implicit Memory

Evidence suggests that physical changes in word appearance, such as those written in all capital letters, and the use of effective encoding strategies, such as self-referential processing, improves memory. In this study we examined the extent both physical changes in word appearance (case) and encoding strategies engaged at study influence memory as measured by both explicit and implicit memory measures. Participants studied words written in upper and lower case under three encoding conditions (self-reference, semantic control, case judgment), which was followed by an implicit (word stem completion) and then an explicit (item and context) memory test. There were two primary results. First, analyses indicated a case enhancement effect for item memory where words written in upper case were better remembered than lower case, but only when participants were prompted to attend to the case of the word. Importantly, this case enhancement effect came at a cost to context memory for words written in upper case. Second, self-referencing increased explicit memory performance relative to control, but there was no effect on implicit memory. Overall, results suggest an item-context memory trade-off for words written in upper case, highlighting a potential downside to writing in all capital letters, and further, that both physical changes to the appearance of words and differing encoding strategies have a strong influence on explicit, but not implicit memory

Cognition, Persuasion and Decision Making in Older Consumers

Older adults constitute a rapidly growing demographic segment, but relatively little is known about them within consumer contexts: how they process information, respond to persuasive messages, and make decisions. We discuss extant findings from consumer behavior and related disciplines (e.g., cognitive psychology, neuroscience, social psychology, gerontology) as they pertain to the effects of aging on consumer memory, persuasion and decisionPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47045/1/11002_2005_Article_5903.pd

The neural correlates of picture encoding: fMRI investigations of age and cross -cultural differences.

I investigate the effects of neurobiology and environment on plasticity in brain function, specifically seeking evidence for functional compensation with aging and culturally-distinct neural activation for picture encoding. Study one investigates the hypothesis that increased prefrontal activations in older adults are compensatory for decreases in medial temporal activations that occur with age. Because between-group comparisons of high- and low-performing elderly have yielded inconsistent results, it is unclear whether additional activations in older adults reflect compensation. We examined incidental encoding of scenes using functional MRI in a subsequent memory paradigm, which isolates successfully encoded (remembered) items. Younger and older adults both activated inferior frontal and lateral occipital regions bilaterally; however, older adults showed less activation than young in the parahippocampus and more activation than young in prefrontal cortex. Because the findings are unique for remembered but not forgotten items, these data suggest that prefrontal regions could serve a compensatory role for declines in medial temporal activations with age. Study two examines whether culturally-distinct modes of information processing are neurally distinguishable. Using an event-related fMRl design, we investigate the hypothesis that Westerners engage in object-based processing with less regard to the entire context as opposed to East Asians, who process objects in terms of relationships and contexts (Nisbett, 2003). American and East Asian participants incidentally encoded pictures of target objects, backgrounds, and the combination of the two. Consistent with our hypothesis, Americans activated left middle temporal cortex, which responds to presentation of objects and semantic knowledge about properties of objects, more than East Asians when pictures of objects on backgrounds were contrasted with those of backgrounds alone. Although both cultures similarly activated the fusiform region when complex pictures were contrasted with those of objects only, reflecting form and context processing, the more negative correlations between fusiform and middle temporal gyri for East Asians than Americans suggest that the region may be differently involved in task performance for the two cultures. These results suggest that fundamental differences exist cross-culturally in the type of information encoded from pictures, with Americans engaging additional object-based and semantic processing for pictures when salient central objects are present.Ph.D.Cognitive psychologyPsychologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/124067/2/3121937.pd