Differences in Fear of Isolation as an explanation of Cultural Differences: Evidence from memory and reasoning

Previous research suggests that members of East Asian cultures show a greater preference for dialectical thinking and sensitivity to context information than do Westerners. We suggest this difference is rooted in a greater chronic Fear of Isolation (FOI) in East Asians than in Westerners. To support this hypothesis, we manipulated FOI in a group of Westerners and assessed their relative preference for dialectical proverbs and sensitivity to context. For cross-cultural validation of our hypothesis, we assessed the relationship between chronic levels of FOI and dialectical reasoning in Koreans. Consistent with our proposal, both experimentally primed FOI (Experiment 1A and 2) and chronic levels of FOI (Experiment 1B) were positively related to relative preference for dialectical proverbs. This effect was independent of participants’ level of negative mood (Experiment 2). A third experiment showed that sensitivity to context was affected by FOI in a manner consistent with previous studies of cultural differences (Experiment 3).     

Individual differences in information order effects: The importance of right-hemisphere access in belief updating

The order in which information is received alters the evaluation of causal hypotheses. Specifically, research suggests that the last piece of information oftentimes has the greatest impact on the evaluation and that the difference in subjective value between two pieces of information is an important factor influencing the magnitude of this recency effect. The present paper extends this line of work by exploring individual differences in this phenomenon via one's degree of handedness. Two hundred and five participants were given two hypothetical scenarios and related causal hypotheses accompanied by two pieces of additional information and asked to revise their belief in each hypothesis as information accumulated. Results confirmed predictions that 1) inconsistent/mixed-handers (those who use their non-dominant hand for at least some activities) show a larger effect with two pieces of inconsistent weak or strong information, and 2) neither mixed-handers nor consistent/strong-handers (those who use their dominant hand for almost all activities) show an effect with strong and weak pieces of consistent information. Mixed-handers' susceptibility to persuasive arguments and Ramachandran’s (1995; Ramachandran and Blakeslee, 1998) belief-updating theory centered around communication between the two halves of the brain and functional access to the right hemisphere are used to account for these data.     

The effects of stress and stress hormones on human cognition: Implications for the field of brain and cognition

In this review, we report on studies that have assessed the effects of exogenous and endogenous increases in stress hormones on human cognitive performance. We first describe the history of the studies on the effects of using exogenous stress hormones such as glucocorticoids as anti-inflammatory medications on human cognition and mental health. Here, we summarize the cases that led to the diagnosis of glucocorticoid-induced 'steroid psychosis' in human populations and which demonstrated that these stress hormones could thus cross the blood-brain barrier and access the brain where they could influence cognition and mental health. We then summarize studies that assessed the effects of the exogenous administration of glucocorticoids on cognitive performance supported by the hippocampus, the frontal lobes and amygdala. In the second section of the paper, we summarize the effects of the endogenous release of glucocorticoids induced by exposure to a stressful situation on human cognition and we further dissociate the effects of emotion from those of stress on human learning and memory. Finally, in the last section of the paper, we discuss the potential impact that the environmental context to which we expose participants when assessing their memory could have on their reactivity to stress and subsequent cognitive performance. In order to make our point, we discuss the field of memory and aging and we suggest that some of the 'age-related memory impairments' observed in the literature could be partly due to increased stress reactivity in older adults to the environmental context of testing. We also discuss the inverse negative correlations reported between hippocampal volume and memory for young and older adults and suggest that these inverse correlations could be partly due to the effects of contextual stress in young and older adults, as a function of age-related differences in hippocampal volume.     

Aging and strategic retrieval in a cued-recall test: the role of executive functions and fluid intelligence

Cued-recall in episodic memory was investigated in relation to low and high cognitive support at retrieval, executive function level and fluid intelligence level in 81 healthy adults divided first into two age groups (young and elderly adults). The first analyses showed that age-related differences were greater when a low cognitive support was provided to recall the words. An individual index of loss of performance when the number of cues was decreased was then calculated. Hierarchical regression analysis revealed that the executive functions measure (perseverative errors on the Wisconsin Card Sorting Test) was a better candidate than the fluid intelligence measure (Cattell's culture fair test) to account for the age-related variance of the size of performance loss. These findings suggest that age differences in implementing strategic retrieval may be mainly due to a decline in executive functions.     

Intrahippocampal insulin improves memory in a passive-avoidance task in male wistar rats

The main impacts of insulin favor the peripheral organs. Although it functions as a neuropeptide, insulin possesses also some central effects. The aim of this study was to determine the effect of intrahippocampal infusion of insulin on passive avoidance learning in healthy male rats. Thirty male wistar rats were divided into three groups (n=10 each). The experimental group had posttraining insulin infusion into the CA1 region of dorsal hippocampus, after which they were compared with sham (saline) and control (intact) groups. Insulin treated animals had greater latency to enter the dark compartment in compare with saline treated (p=0.023) or control groups (p=0.017). Upon our results, we concluded that intrahippocampal injections of insulin may enhance memory for a simple learning task which supports the concept that insulin possibly plays an endogenous role in memory formation.     

An analogue study of the effects of Psychological Debriefing on eyewitness memory

Sixty-one participants from the community participated in a randomised controlled trial of group debriefing to assess the effect of this intervention upon memory for a stressful event. Participants were randomly allocated to one of three groups: debriefing; debriefing with an experimenter confederate present (who supplied three pieces of misinformation to the group regarding the stressful event); and a no-treatment control. All groups were shown a very stressful video and were again reviewed after 1 month. Members of the debriefing group where a confederate provided misinformation were more likely to recall this misinformation as fact than members of the other two groups. The debriefing group was also more accurate in their recall of peripheral content than the confederate group. Across all groups, participants were found to be more accurate at central rather than peripheral recall yet more confident for incorrect memories of the video than correct memories.     

Enhanced perceived responsibility decreases metamemory but not memory accuracy in obsessive-compulsive disorder (OCD)

Mixed findings have been obtained in prior research with respect to the presence and severity of memory and metamemory deficits in obsessive-compulsive disorder (OCD). We tested the hypothesis that experimentally induced increments of subjective responsibility would lead to a disproportionately strong decline of memory confidence and enhanced response latencies in OCD while leaving memory accuracy unaffected. Twenty-eight OCD patients and 28 healthy controls were presented a computerized memory test framed with two different scenarios. In the neutral scenario, the participant was requested to imagine purchasing 15 items from a do-it-yourself store. In the recognition phase, the 15 needed items were presented along with 15 distractor items. The participant was asked to decide whether items were on his or her shopping list or not, graded by subjective confidence. In the responsibility scenario, the general experimental setup was analogous except that the participant now had to envision that he or she was a helper in a region recently struck by an earthquake, dispatched to provide 15 urgently needed goods from a nearby town. In line with prior work by our group, samples did not differ in either condition on memory accuracy in a subsequent recognition task. As hypothesized, OCD participants were less certain in their responses for the high responsibility condition than controls. Whereas patients and controls did not differ in their subjective estimates for memorized items, patients expressed stronger doubt that their earthquake mission was successful. The findings indicate that low memory confidence in OCD may only be elicited in situations where perceived responsibility is high and that patients may share higher performance standards ("good is not good enough") than controls when perceived responsibility is inflated.     

Does providing props during preparation help children to remember a novel event?

We investigated the conditions under which preparatory information presented 1 day before a novel event influenced 6-year-olds' recall 1 week later. Children were assigned to one of six experimental conditions. Three conditions involved preparatory information that described the event accurately but differed according to the presence and type of props (verbal, real props, and toy props). In two conditions, which also differed according to whether verbal information was supplemented with real props, half of the preparatory information described the event accurately, whereas the other half was thematically similar to, but inconsistent with, the event (misleading verbal and misleading props). Compared with the attentional control condition, all forms of preparation that described the event accurately increased correct recall. Preparation that included props improved photograph recognition. When half of the accurate information was replaced by misleading information, the positive benefit on recall was reduced, and when misleading props accompanied the misleading information, errors increased. The potential underlying mechanisms and implications for pediatric settings are discussed.     

The development of memory for own- and other-race faces

This study demonstrates that experience and development interact to influence the "cross-race effect." In a multination study (n=245), Caucasian children and adults of European ancestry living in the United States, Norway, or South Africa, as well as biracial (Caucasian-African American) children and adults living in the United States, were tested for recognition of Asian, African, and Caucasian faces. Regardless of national or biracial background, 8- to 10-year-olds, 12- to 14-year-olds, and adults recognized own-race faces more accurately than other-race faces, and did so to a similar extent, whereas 5- to 7-year-olds recognized all face types equally well. This same developmental pattern emerged for biracial children and adults. Thus, early meaningful exposure did not substantially alter the developmental trajectory. During young childhood, developmental influences on face processing operate on a system sufficiently plastic to preclude, under certain conditions, the cross-race effect.     

Recent Innovative Studies of Memory in Temporal Lobe Epilepsy

Investigations of patients with temporal lobe epilepsy continue to result in significant advancements in the neuroscience of human memory, as they have for over 50 years. Recent reviews describing the state of the art in the clinical neuropsychology of TLE generally have emphasized (1) lateralization of cognitive deficits and the material-specific model of memory and/or (2) the relationships among pre- and post-surgery performance on standardized measures of anterograde memory, demographic and epilepsy variables and neuroimaging, neuropathology, and neurosurgery data. As information continues to accumulate about the pattern of performance on standard laboratory memory tests and the implications of these data before and after anterior temporal lobectomy for the treatment of TLE, innovative assessment techniques also are increasingly being applied. This review focuses on English language publications that addressed selected novel topics in adult TLE memory research. These topics are: (1) remote memory; (2) accelerated forgetting or long term amnesia; and (3) lateral versus mesial temporal lobe contributions to memory.