Geometry,landmarks and the cerebral hemispheres: 2D spatial reorientation in split‐brain patients

A right‐hemispheric superiority in spatial encoding based on geometric cues has been largely documented in a variety of species, together with a left‐hemispheric specialization for encoding based on landmarks. In humans, hemispheric asymmetries for spatial encoding have been little explored. In this study, we compared a patient with a complete callosal resection (D.D.C.) and a patient with a wide callosal resection saving the splenium (A.P.), with healthy participants. In two 2D versions of the ‘reorientation task’, participants were asked to find the target corner of a rectangle‐shaped environment, by exploiting either geometric information alone or the combination of geometric and landmark information. In Experiment 1, the landmark consisted of a coloured side of the rectangle; in Experiment 2, this cue was replaced by a coloured disc located inside the rectangle. In both experiments, the rectangular shape ensured the geometric cue. D.D.C. was always unable to recall the target, whereas A.P. correctly solved the task when only the geometric information was available, without difference with respect to the controls. Importantly, the performance of A.P. did not differ from controls’ when the right hemisphere was tested with the landmark cues (the task being carried out using the left hand), whereas when the left hemisphere was tested (right‐hand session) his performance was worse than controls’ with the coloured side of the space, but it was better than controls’ with the coloured disc. The results are discussed comparing them with data collected on other species, and with theories of spatial processing.     

Hypermnesia in older people and its relationship with successful ageing / La hipermnesia en personas mayores y su relación con el envejecimiento exitoso

Abstract

This study analyses the phenomenon of hypermnesia and its relationship with variables associated with successful ageing such as age, sex, cognitive status and cognitive plasticity in older people. The sample consists of 124 institutionalized and non-institutionalized participants, whose ages ranged from 65 to 91. A specific task was used to evaluate hypermnesia; a cognitive screening test and a verbal fluency test were used to assess cognitive status, and the AVLT-LP test was used to measure cognitive plasticity. The results show significant improvements between the hypermnesia recall tests for the total sample and for all the groups, according to the variables studied. Participants with successful ageing characterized by a younger age, a high level of cognitive functioning and a greater cognitive plasticity showed better results than the other participants in the hypermnesia task with the exception of sex, which did not present differences between groups. This study confirms that hypermnesia occurs more significantly in older people with successful ageing regardless of whether they are male or female.     

Do Friends’ Characteristics Moderate the Prospective Links between Peer Victimization and Reactive and Proactive Aggression?

This study examined (a) the predictive link between peer victimization and children’s reactive and proactive aggression, and (b) the potential moderating effect of reciprocal friends’ reactive and proactive aggression in this context. The study also examined whether these potential moderating effects of friends’ characteristics were stronger with respect to more recent friends compared to previous friends. Based on a convenience sample of 658 twin children (326 boys and 332 girls) assessed in kindergarten and first grade, the results showed that peer victimization uniquely predicted an increase in children’s teacher-rated reactive aggression, but not teacher-rated proactive aggression. The relation of peer victimization to increased reactive aggression was, however, moderated by recent ˉ not previous ˉ reciprocal friends’ similarly aggressive characteristics. These findings, however, tended to be mostly true for boys, but not for girls. The findings are discussed in terms of their theoretical and practical implications for victimized children’s risk of displaying reactive and proactive aggressive behaviors. This research was made possible by grants from the Social Sciences and Humanities Research Council of Canada, the Fonds Concerté pour l’Aide à la Recherche, the Fonds Québécois de la Recherche sur la Société et la Culture, the Canadian Institutes of Health Research, and the Fonds de Recherche en Santé du Québec.     

Conflicting social motives in negotiating groups

Negotiators' social motives (cooperative vs. individualistic) influence their strategic behaviors. In this study, the authors used multilevel modeling and analyses of strategy sequences to test hypotheses regarding how negotiators' social motives and the composition of the group influence group members' negotiation strategies. Four-person groups negotiating a 5-issue mixed-motive decision-making task were videotaped, and the tapes were transcribed and coded. Group composition included 2 homogeneous conditions (all cooperators and all individualists) and 3 heterogeneous conditions (3 cooperators and 1 individualist, 2 cooperators and 2 individualists, 1 cooperator and 3 individualists). Results showed that cooperative negotiators adjusted their use of integrative and distributive strategies in response to the social-motive composition of the group, but individualistic negotiators did not. Results from analyses of strategy sequences showed that cooperators responded more systematically to others' behaviors than did individualists. They also redirected the negotiation depending on group composition.     

Emotional Arousal and Memory Binding: An Object-Based Framework

ABSTRACT— Binding various features of an event together and maintaining these connections in memory is an essential component of episodic memories. Previous theories make contradictory predictions about the effects of emotional arousal on memory binding. In this article, I review evidence for both arousal-impaired and arousal-enhanced memory binding and explain these contradictory findings using an object-based framework. According to this framework, emotionally arousing objects attract attention that enhances binding of their constituent features. In contrast, the emotional arousal associated with one object either impairs or has no effect on the associations between that object and other distinct objects or background contextual information. After initial encoding, the attention-grabbing nature of emotionally arousing objects can lead to interference in working memory, making it more difficult to maintain other bound representations. These contrasting effects of arousal on memory binding should help predict which aspects of emotional memories are likely to be accurate and which aspects are likely to be misremembered.     

The tenacious nature of memory binding for arousing negative items

In two experiments, we investigated whether people are better or worse at updating memory for the location of emotional pictures than of neutral pictures. We measured participants’ memories for the locations of both arousing negative pictures and neutral pictures while manipulating practice (encountering the same event repeatedly) and interference (encountering the same picture in a different location). Memory for the context of emotional items was less likely to be corrected when erroneous and was less likely to be correctly updated when the context changed. These results suggest that initial item-context binding is more tenacious for emotional items than for neutral items, even when such binding is incorrect.     

Split-Brain: What We Know Now and Why This is Important for Understanding Consciousness

Neuropsychology Review - Recently, the discussion regarding the consequences of cutting the corpus callosum (“split-brain”) has regained momentum (Corballis, Corballis, Berlucchi,...     

Associations between young children's emotion attributions and prediction of outcome in differing social situations

Associations between young children's attributions of emotion at different points in a story, and with regard to their own prediction about the story's outcome, were investigated using two hypothetical scenarios of social and emotional challenge (social entry and negative event). First grade children (N=250) showed an understanding that emotions are tied to situational cues by varying the emotions they attributed both between and within scenarios. Furthermore, emotions attributed to the main protagonist at the beginning of the scenarios were differentially associated with children's prediction of a positive or negative outcome and with the valence of the emotion attributed at the end of the scenario. Gender differences in responses to some items were also found.     

Four days later in Cincinnati: longitudinal tests of hyperbolic discounting

Hyperbolic discounting of delayed rewards has been proposed as an underlying cause of the failure to stick to plans to forego one's immediate desires, such as the plan to diet, wake up early, or quit taking heroin. We conducted two tests of inconsistent planning in which respondents made at least two choices between a smaller-sooner (SS) and larger-later (LL) amount of money, one several weeks before SS would be received, and one immediately before. Hyperbolic discounting predicts that there would be more choices of SS as it became more proximate-and, equivalently, that among those who change their mind, "impatient shifts" (LL-to-SS) will be more common than "patient shifts" (SS-to-LL). We find no evidence for this, however, and in our studies shifts in both directions were equally likely. We propose that some of the evidence cited on behalf of hyperbolic discounting can be attributed to qualitatively different psychological mechanisms.     

Self-stereotyping: the central role of an ingroup threatening identity

Self-stereotyping is a process by which people belonging to a stigmatized social group tend to describe themselves more with stereotypical traits as compared with traits irrelevant to the ingroup stereotype. The present work analyzes why especially members of low-status groups are more inclined to self-stereotype compared to members of high-status groups. We tested the hypothesis that belonging to a low-, rather than a high-status group, makes low-status members feel more threatened and motivates them to protect their self-perception by increasing their similarity with the ingroup. Specifically, we investigated the effects of an experimental manipulation that was conceived to either threaten or protect the natural group membership of participants from either a low- or a high-status group on the level of self-stereotyping. The findings supported the idea that only low-status group members protected themselves when their group identity was threatened through increased self-stereotyping.