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.     

When is individual mobility costly? The role of economic and social identity factors

Two studies considered when the individual mobility strategy of attending university has psychological costs in terms of poor adjustment to university life. Study 1, (N = 74) examined both economic considerations affecting university choice and identity‐related factors among open day attendees. Expected identification as a university student and preparedness for university life was affected by economic factors (economic benefit of university attendance and status of the considered universities) but also negatively related to perceived incompatibility with one's social background. These findings were replicated in a longitudinal study in which students' perceptions were assessed before entering university (T1), after being at university for two months (T2) and again after being at university for 8 months (T3; N = 109). Social class (T1) predicted perceived incompatibility but not economic factors. In addition, economic factors and incompatibility predicted group identification (T2) but only perceived incompatibility predicted longer‐term identification (T3). Belief that university education serves as a successful individual mobility strategy (T3) was indirectly negatively affected by initial incompatibility (T1), but positively with perceiving economic benefits of a university degree (T1). Implications for the (economic) benefits versus (identity) costs of individual mobility strategies are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Common Genetic and Environmental Influences on Major Depressive Disorder and Conduct Disorder

The evidence for common genetic and environmental influences on conduct disorder (CD) and major depressive disorder (MDD) in adolescents was examined. A sample of 570 monozygotic twin pairs, 592 dizygotic twin pairs, and 426 non-twin siblings, aged 12-18 years, was recruited from the Colorado Twin Registry. For the past year data, there was a significant correlation between the genetic influences on MDD and CD and, for the lifetime data, there was a significant correlation between the genetic influences on MDD and CD, and a significant correlation between the nonshared environmental influences on MDD and CD. Our results suggest that some genetic factors will increase an individual's vulnerability to both MDD and CD in adolescence.     

How should we revise diagnostic criteria for substance use disorders in the DSM-V?

This article reviews literature on the validity and performance characteristics of the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) diagnostic criteria for substance use disorders (SUDs) and recommends changes in these criteria that should be considered for the next edition of the DSM (DSM-V). Substantial data indicate that DSM-IV substance abuse and substance dependence are not distinct categories and that SUD criteria are best modeled as reflecting a unidimensional continuum of substance-problem severity. The conceptually and empirically problematic substance abuse diagnosis should be abandoned in the DSM-V, with substance dependence defined by a single set of criteria. Data also indicate that various individual SUD criteria should be revised, dropped, or considered for inclusion in the DSM-V. The DSM-V should provide a framework that allows the integration of categorical and dimensional approaches to diagnosis. Important areas for further research are noted.     

Color change as a causal agent revisited

Michotte (1946/1963, p. 235) concluded that color "has no bearing whatever on the question of qualitative causality". Surprisingly, this claim has received little empirical investigation in the 60 years since its publication. In 2 experiments, 2 balls struck a cylinder and changed color (either continuously or in a stepped progression) for 2 s. After the 2-s interval, the cylinder disgorged a purple substance. Participants chose which of the 2 balls was most likely to have caused the disgorging effect. An object that changed color was favored as the cause much more often than one that did not, and participants generally preferred an object that reached its terminal color immediately before the effect over objects that reached their terminal colors earlier. When participants performed a causal ratings task, color change produced moderate judgments of causation, with little response differentiation as a function of color dynamics.     

The impact of object animacy on the appraisal of causality

The goal of this study was to examine whether animacy of objects affected the appraisal of a causal relationship when one object was observed to propel the other either immediately, after a delay, or at a distance. Participants rated the degree of causal interaction either before or after an extended experience with observing the interactions. We expected that spatial distance would have little effect when objects were seen as animate (because social interactions often span spatial gaps) and would have a degrading effect when objects were appraised as inanimate. Motion animacy appeared to attenuate the impact of a gap and to decrease initial causal judgments for direct collisions. Explicitly informing participants about the nature of the objects had a strong impact. Experience with the causal task affected ratings to a greater extent when the objects were explicitly described as nonliving rather than living.     

Pathways to suicidal behaviors in childhood

Path analyses were applied to test a model that includes internalizing and externalizing behavior problems as predictors of suicidal behaviors in children. Parents of an inpatient sample of boys (N=87; M age=9.81 years) rated the frequency of suicidal ideation and completed standardized measures of behavior problems. Blind raters rated the severity of the children's suicidal behaviors. Results revealed a significant direct effect for suicidal ideation on suicide attempt and for depressive symptoms on suicidal ideation. There was also a significant indirect path from impulsivity to suicidal ideation through aggressive and depressive symptoms. Clinical implications are discussed.     

On how a child's awareness of thinking informs explanations of thought insertion

Theories of thought insertion have tended to favour either the content of the putatively alien thought or some peculiarity within the experience itself as a means of explaining why the subject differentiates one thought from another in terms of personal ownership. There are even accounts that try to incorporate both of these characteristics. What all of these explanations share is the view that it is unexceptional for us to experience thought as our own. The aim of this paper is to consider the means by which this awareness of the myness of thought occurs. Why is it that I, as the subject of thought, typically experience a thought as mine? Using research which investigates the development of a child's awareness of the act of thinking, I will evaluate leading explanations of thought insertion. It is my contention that by understanding the means by which the awareness of one's ownership of thought develops, we can better assess explanations of thought insertion; and whilst, at present, no theory is fully able to explain the condition, the incorporation of developmental research suggest that we should favour one in particular.     

Feedback and driver situation awareness (SA): A comparison of SA measures and contexts

The dominant technological trajectory in vehicle design brings with it similarly dominant driver performance issues in regard to vehicle feedback and driver situational awareness (SA). Three experiments are reported in this paper that describe not only the effects on driver SA of manipulations of vehicle feedback but also illuminate issues concerned with SA measurement methods and contexts. The findings suggest that current trends in vehicle design may contribute little towards a driver’s SA and, in fact, may actually show a generalized trend towards decreasing it. The efficacy of verbal protocol and probe recall SA measurement techniques is noted in terms of observing this effect. On the other hand, a concerning dissociation occurred with findings from a self-report measure of SA. Drivers appear to show a concerning lack of self-awareness of their SA and, indeed, any shortfall in it.     

Pilot study for assessing the behaviors of patients with schizophrenia towards a virtual avatar.

This study examined whether a virtual avatar could be perceived as a real human by patients with mental disease, especially schizophrenia, as well as whether a virtual avatar could be applied to acquiring patients' behavior characteristics in a short conversation situation. The virtual avatar has been used for various applications which need to communicate with other person or to train or educate by showing humanlike behavior. Recently, many researches have shown that the virtual avatar technology has been enhanced and the avatar could be perceived like real human. A virtual avatar, standing in a virtual room, was designed for this study. Tasks to approach, initiate a talk, and answer to avatar's questions was assigned to the 11 patients with schizophrenia. As behavioral parameters in the virtual environment, the interpersonal distance and the verbal response time were acquired. In addition, the Positive and Negative Syndrome Scale (PANSS) for patients was administered in order to investigate the relationship between patients' symptomatic characteristics and behavior parameters. The interpersonal distance was negatively correlated with the negative syndrome scale, a subscale of PANSS, which is consistent with previous research reporting the relationship between interpersonal distance and a real person's image. The verbal response time, however, was not correlated with any other subscale of PANSS. After analyzing subitems of the negative syndrome of PANSS, two positive correlations were found: one was with blunted affect and the other was with poor rapport. We concluded that the virtual avatar could be perceived as a real human by schizophrenic patients and the avatar could draw the schizophrenic patients' behavior characteristics.