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

When True Recognition Suppresses False Recognition: Evidence from Amnesic Patients

False recognition occurs when people mistakenly claim that a novel item is familiar. After studying lists of semantically related words, healthy controls show extraordinarily high levels of false recognition to nonstudied lures that are semantic associates of study list words. In previous experiments, we found that both Korsakoff and non-Korsakoff amnesic patients show reduced levels of false recognition to semantic associates, implying that the medial temporal/diencephalic structures that are damaged in amnesic patients are involved in the encoding and/or retrieval of information that underlies false recognition. These data contrast with earlier results indicating greater false recognition in Korsakoff amnesics than in control subjects. The present experiment tests the hypothesis that greater or lesser false recognition of semantic associates in amnesic patients, relative to normal controls, can be demonstrated by creating conditions that are more or less conducive to allowing true recognition to suppress false recognition. With repeated presentation and testing of lists of semantic associates, control subjects and both Korsakoff and non-Korsakoff amnesics showed increasing levels of true recognition across trials. However, control subjects exhibited decreasing levels of false recognition across trials, whereas Korsakoff amnesic patients showed increases across trials and non-Korsakoff amnesics showed a fluctuating pattern. Consideration of signal detection analyses and differences between the two types of amnesic patients provides insight into how mechanisms of veridical episodic memory can be used to suppress false recognition.Psycholog

Remembering what could have happened: Neural correlates of episodic counterfactual thinking

Recent evidence suggests that our capacities to remember the past and to imagine what might happen in the future largely depend on the same core brain network that includes the middle temporal lobe, the posterior cingulate/retrosplenial cortex, the inferior parietal lobe, the medial prefrontal cortex, and the lateral temporal cortex. However, the extent to which regions of this core brain network are also responsible for our capacity to think about what could have happened in our past, yet did not occur (i.e., episodic counterfactual thinking), is still unknown. The present study examined this issue. Using a variation of the experimental recombination paradigm (Addis, Pan, Vu, Laiser, & Schacter, 2009. Neuropsychologia. 47: 2222–2238), participants were asked both to remember personal past events and to envision alternative outcomes to such events while undergoing functional magnetic resonance imaging. Three sets of analyses were performed on the imaging data in order to investigate two related issues. First, a mean-centered spatiotemporal partial least square (PLS) analysis identified a pattern of brain activity across regions of the core network that was common to episodic memory and episodic counterfactual thinking. Second, a non-rotated PLS analysis identified two different patterns of brain activity for likely and unlikely episodic counterfactual thoughts, with the former showing significant overlap with the set of regions engaged during episodic recollection. Finally, a parametric modulation was conducted to explore the differential engagement of brain regions during counterfactual thinking, revealing that areas such as the parahippocampal gyrus and the right hippocampus were modulated by the subjective likelihood of counterfactual simulations. These results suggest that episodic counterfactual thinking engages regions that form the core brain network, and also that the subjective likelihood of our counterfactual thoughts modulates the engagement of different areas within this set of regions.Psycholog

Deese-roediger-McDermott paradigm: Effect of previous recall and type of memory task

Pretendeu-se averiguar se a activação dos itens críticos no paradigma de Deese-Roediger-McDermott também ocorreria numa tarefa de completamento. Para analisar a contaminação explícita explorámos a existência de resultados dissociados em função da manipulação do nível de processamento. Na tarefa de completamento, a primação semântica foi estatisticamente superior à primação directa. A ausência do efeito do nível de processamento demonstra que o teste foi de memória implícita. Também avaliámos o impacto de uma tarefa de evocação numa tarefa de memória posterior. Verificámos que a evocação prévia anulou o efeito do nível de processamento na tarefa de reconhecimento. Na tarefa de completamento de inícios de palavras, o incremento de inícios de palavras completados com associados só foi expressivo quando as palavras foram codificadas superficialmente.This study aimed to verifj whether lhe activation ofcritical items in the Deese-Roediger-McDermott paradigm ofproducing false memories could also occur in the word stem completion task. The finding that lhe levei ofprocessing did not seem to have any effect on the word stem completion task supported lhe conclusion that the stem completion task was in fact an irnplicit memory test. The impact of a previous recali in a followng memory task was also evaluated. The results indicated that lhe previous recall inhibited the effect ofthe processing levei in lhe recognition task. In the word stem completion task lhe increase ofstems completed with associates was only relevam when words were encoded superficialiy.(undefined

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

Neural Correlates of True Memory, False Memory, and Deception

We used functional magnetic resonance imaging (fMRI) to determine whether neural activity can differentiate between true memory, false memory, and deception. Subjects heard a series of semantically related words and were later asked to make a recognition judgment of old words, semantically related nonstudied words (lures for false recognition), and unrelated new words. They were also asked to make a deceptive response to half of the old and unrelated new words. There were 3 main findings. First, consistent with the notion that executive function supports deception, 2 types of deception (pretending to know and pretending not to know) recruited prefrontal activity. Second, consistent with the sensory reactivation hypothesis, the difference between true recognition and false recognition was found in the left temporoparietal regions probably engaged in the encoding of auditorily presented words. Third, the left prefrontal cortex was activated during pretending to know relative to correct rejection and false recognition, whereas the right anterior hippocampus was activated during false recognition relative to correct rejection and pretending to know. These findings indicate that fMRI can detect the difference in brain activity between deception and false memory despite the fact that subjects respond with “I know” to novel events in both processes

A Self-Reference False Memory Effect in the DRM Paradigm: Evidence from Eastern and Western Samples

It is well established that processing information in relation to oneself (i.e., selfreferencing) leads to better memory for that information than processing that same information in relation to others (i.e., other-referencing). However, it is unknown whether self-referencing also leads to more false memories than other-referencing. In the current two experiments with European and East Asian samples, we presented participants the Deese-Roediger/McDermott (DRM) lists together with their own name or other people’s name (i.e., “Trump” in Experiment 1 and “Li Ming” in Experiment 2). We found consistent results across the two experiments; that is, in the self-reference condition, participants had higher true and false memory rates compared to those in the other-reference condition. Moreover, we found that selfreferencing did not exhibit superior mnemonic advantage in terms of net accuracy compared to other-referencing and neutral conditions. These findings are discussed in terms of theoretical frameworks such as spreading activation theories and the fuzzytrace theory. We propose that our results reflect the adaptive nature of memory in the sense that cognitive processes that increase mnemonic efficiency may also increase susceptibility to associative false memories

Distinctive Encoding Reduces the Jacoby-Whitehouse Illusion

We investigated the influence of distinctive encoding on the Jacoby and Whitehouse (1989) illusion. Subjects studied visually presented words that were associated with either an auditory presentation of the same word (non-distinctive encoding) or a picture of the object (distinctive encoding). In both conditions, words were visually presented on the recognition test, and half were preceded by brief repetition primes. Priming test items increased hits and false alarms in the auditory condition, demonstrating the Jacoby-Whitehouse illusion. This illusion was reduced in the picture condition. In order to test whether this distinctiveness effect was caused by a recollection-based response strategy (i.e., the distinctiveness heuristic), we minimized recollection-based responding by having subjects make speeded recognition decisions. Contrary to the distinctiveness heuristic hypothesis, speeded responding did not eliminate the distinctiveness effect on the Jacoby-Whitehouse illusion. Picture encoding may reduce this illusion via a shift in preretrieval orientation, as opposed to a postretrieval editing process.Psycholog