Individual differences in executive functions are almost entirely genetic in origin

Recent psychological and neuropsychological research suggests that executive functions--the cognitive control processes that regulate thought and action--are multifaceted and that different types of executive functions are correlated but separable. The present multivariate twin study of 3 executive functions (inhibiting dominant responses, updating working memory representations, and shifting between task sets), measured as latent variables, examined why people vary in these executive control abilities and why these abilities are correlated but separable from a behavioral genetic perspective. Results indicated that executive functions are correlated because they are influenced by a highly heritable (99%) common factor that goes beyond general intelligence or perceptual speed, and they are separable because of additional genetic influences unique to particular executive functions. This combination of general and specific genetic influences places executive functions among the most heritable psychological traits. These results highlight the potential of genetic approaches for uncovering the biological underpinnings of executive functions and suggest a need for examining multiple types of executive functions to distinguish different levels of genetic influences.     

Pride and respect in volunteers' organizational commitment

As volunteer organizations cannot rely on instrumental means to motivate their workers, we examine organizational commitment as a focal indicator of work motivation among volunteers. Based on a social identity analysis and previous work among paid employees, we argue that pride in the organization and respect from the organization predicts organizational commitment among volunteers. We further propose that among volunteers the perceived importance of volunteer work is an antecedent of pride, and that perceived support from the organization is an antecedent of respect. In this study among volunteer workers, Structural Equation Modeling (SEM) offers empirical support for our hypothesized model. In addition to the theoretical significance of developing a model that explains organizational commitment among volunteer workers, this study also has practical relevance, as it indicates that volunteer organizations might convey the importance of volunteer work and provide organizational support to induce pride and respect as a means of enhancing organizational commitment among their volunteers. Copyright © 2007 John Wiley & Sons, Ltd.     

Human topological task adapted for rats: Spatial information processes of the parietal cortex

Human research has shown that lesions of the parietal cortex disrupt spatial information processing, specifically topological information. Similar findings have been found in non-humans. It has been difficult to determine homologies between human and non-human mnemonic mechanisms for spatial information processing because methodologies and neuropathology differ. The first objective of the present study was to adapt a previously established human task for rats. The second objective was to better characterize the role of parietal cortex (PC) and dorsal hippocampus (dHPC) for topological spatial information processing. Rats had to distinguish whether a ball inside a ring or a ball outside a ring was the correct, rewarded object. After rats reached criterion on the task (>95%) they were randomly assigned to a lesion group (control, PC, and dHPC). Animals were then re-tested. Post-surgery data show that controls were 94% correct on average, dHPC rats were 89% correct on average, and PC rats were 56% correct on average. The results from the present study suggest that the parietal cortex, but not the dHPC processes topological spatial information. The present data are the first to support comparable topological spatial information processes of the parietal cortex in humans and rats.     

Hide and seek: the effects of revealing one's personal interests in intra‐ and intergroup negotiations

The present research examined the effects of information sharing about self‐interest and group membership of the negotiation partner on negotiation cognitions, behaviors and outcomes. Study 1 (n = 77) showed that in anticipation of the negotiation, participants placed more trust in an in‐group member, and were more willing to exchange information with a negotiation partner who revealed his/her self‐interest. Study 2 (n = 80) examined how these effects influenced the development of attitudes and behavior during and after the negotiation. Results showed that negotiations with in‐group members were more cooperative when they shared, rather than not shared, information about underlying self‐interest. By contrast, negotiations with out‐group members were more cooperative when they did not share, rather than shared, information about their underlying self‐interest. Copyright © 2006 John Wiley & Sons, Ltd.     

The paradox of the disrespected: Disrespected group members’ engagement in group-serving efforts

Previous research has demonstrated that intra-group respect can strengthen people’s group identification, and encourage them to exert themselves on behalf of their group. In the present contribution, we focus on the possibility that those who are not respected by other group members (i.e., the disrespected) can also display group beneficial behavior. Experiment 1 (N = 159) confirms this paradoxical premise and reveals that systematically disrespected group members indeed exert themselves on group-serving tasks. These findings were replicated in Experiment 2 (N = 110). Additional indicators in Experiment 2 demonstrate that the effort by systematically disrespected group members cannot be attributed to a desire to improve their acceptance in the group, but should be interpreted as attempts to assert the worth of the self separately from the group. Results are discussed in relation to the group-value model and insights on marginal group membership and social exclusion.     

Integrating haptic-tactile feedback into a video-capture-based virtual environment for rehabilitation.

Video-capture virtual reality (VR) systems are gaining popularity as intervention tools. To date, these platforms offer visual and audio feedback but do not provide haptic feedback. We contend that adding haptic feedback may enhance the quality of intervention for various theoretical and empirical reasons. This study aims to integrate haptic-tactile feedback into a video capture system (GX VR), which is currently applied for rehabilitation. The proposed multi-modal system can deliver audio-visual as well as vibrotactile feedback. The latter is provided via small vibratory discs attached to the patient's limbs. This paper describes the system, the guidelines of its design, and the ongoing usability study.     

The sibling familiarity effect: Is within-person facial variability shared across siblings?

Humans are experts at familiar face recognition, but poor at unfamiliar face recognition. Familiarity is created when a face is encountered across varied conditions, but the way in which a person’s appearance varies is identity-specific, so familiarity with one identity does not benefit recognition of other individuals. However, the faces of biological siblings share structural similarities, so we explored whether the benefits of familiarity are shared across siblings. Results show that familiarity with one half of a sibling pair improves kin detection (experiment 1), and that unfamiliar face matching is more accurate when targets are the siblings of familiar versus unfamiliar individuals (experiment 2). PCA applied to facial images of celebrities and their siblings demonstrates that faces are generally better reconstructed in the principal components of a same-sex sibling than those of an unrelated individual. When we encounter the unfamiliar sibling of someone we already know, our pre-existing representation of their familiar relation may usefully inform processing of the unfamiliar face. This can benefit both kin detection and identity processing, but the benefits are constrained by the degree to which facial variability is shared.     

Development of a parent training program for children with pervasive developmental disorders

Parent delivered interventions based on applied behavior analysis (ABA) for children with Pervasive Developmental Disorders (PDDs) have been evaluated using primarily single‐subject design methodology or small case series. While the results of these evaluations are encouraging, an important next step is to standardize the interventions to allow for replication across sites, in studies with large samples and measures of long‐term, clinically meaningful outcomes such as improvements in children's functioning and their relationships with parents. Accordingly, the Research Units on Pediatric Psychopharmacology and Psychosocial Interventions (RUPP Autism Network) assembled a detailed manual for a structured behavioral parent training (PT) program, developed treatment fidelity and training procedures, and conducted a pilot, feasibility study. The PT program is part of a large scale, multisite study intended to determine the efficacy of combined pharmacological treatment and behavioral intervention to improve behavior and adaptive functioning in children with PDD. This paper discusses the rationale for this project. A companion paper provides the results of our feasibility study on the PT program. Copyright © 2007 John Wiley & Sons, Ltd.     

Behavioral and neural correlates of memory selection and interference resolution during a digit working memory task

Neuroimaging studies have shown the involvement of prefrontal and posterior parietal cortexes in regulating information processing. We conducted behavioral and fMRI experiments to investigate the relationship between memory selection and proactive interference (PI), using a delayed recognition task with a selection cue presented during the delay indicating which two of the four studied digits were relevant to the present test. PI was indexed by the response time differences between rejecting probes matching and not matching the no longer relevant digits. By varying the delay intervals, we found that the effect of PI did not diminish, even for cases in which the postcue interval was extended to 9 sec, but was stronger when the precue interval was lengthened to 5 sec. By examining the correlation between PI index and neural correlates of memory selection, we found that stronger PI is predicted by lower selection-related activity in the left inferior parietal lobe, the precuneus, and the dorsal middle frontal gyrus. Our results suggest that activity in the prefrontal-parietal network may contribute to one’s ability to focus on the task-relevant information and may proactively reduce PI in working memory.