Dopamine, working memory, and training induced plasticity: implications for developmental research

Cognitive deficits and particularly deficits in working memory (WM) capacity are common features in neuropsychiatric disorders. Understanding the underlying mechanisms through which WM capacity can be improved is therefore of great importance. Several lines of research indicate that dopamine plays an important role not only in WM function but also for improving WM capacity. For example, pharmacological interventions acting on the dopaminergic system, such as methylphenidate, improve WM performance. In addition, behavioral interventions for improving WM performance in the form of intensive computerized training have recently been associated with changes in dopamine receptor density. These two different means of improving WM performance--pharmacological and behavioral--are thus associated with similar biological mechanisms in the brain involving dopaminergic systems. This article reviews some of the evidence for the role of dopamine in WM functioning, in particular concerning the link to WM development and cognitive plasticity. Novel data are presented showing that variation in the dopamine transporter gene (DAT1) influences improvements in WM and fluid intelligence in preschool-age children following cognitive training. Our results emphasize the importance of the role of dopamine in determining cognitive plasticity.     

The Role of Personality in Relation to Gender Differences in School Subject Choices in Pre-University Education

Boys and girls to some extent differ in personality characteristics while they also prefer different school subjects in secondary education. This study has attempted to unravel the relations among gender, personality, and students?? subject choices. The study was based on a sample of 1,740 9th grade pre-university students throughout the Netherlands (average age 15?years). We used the Five-Factor Personality Inventory (FFPI) of Hendriks, Hofstee, and De Raad (1999a) to measure the students?? personalities. The research questions were: (1) To what extent are students?? personality characteristics related to their subject choices in secondary education? (2) Do students?? personality characteristics mediate the gender ?C subject choice relation? And if yes, which personality characteristics are responsible for this? (3) Is the relation between personality characteristics and subject choices different for boys and girls? We found several associations between personality characteristics and students?? subject choices. Although the relationship between gender and students?? subject choices was slightly attenuated after the inclusion of the personality characteristics in the multinomial logistic regression analyses, gender remained an important predictor of the students?? choices. The personality factor Extraversion partially mediated the relation between gender and students?? choice of advanced mathematics, chemistry, and physics versus a more language and culturally-oriented set of school subjects. Furthermore, gender was found to moderate the relation between the personality factor Autonomy and students?? choice of advanced mathematics, chemistry, and physics versus a more language and culturally-oriented set of school courses.     

Threat and selective exposure: the moderating role of threat and decision context on confirmatory information search after decisions

Previous studies on the impact of perceived threat on confirmatory information search (selective exposure) in the context of decision making have yielded mixed results. Some studies have suggested that confirmatory information search is reduced, yet others have found contradictory effects. The present series of 5 studies consistently found that the crucial moderator for these inconsistent findings was whether the induced threat was contextually related to the subsequent decision and information search tasks. Contextual incongruence (e.g., an induction of terrorist threat followed by an economic decision case) results in reduced levels of confirmatory information search, whereas a congruent threat (e.g., an induction of terrorist threat followed by a decision case on terrorism) results in increased levels of confirmatory information search. Analyses of the underlying psychological processes revealed that decision-unrelated threat inductions increase decision makers' experienced decision uncertainty, thus reducing confirmatory information search.     

The bystander-effect: a meta-analytic review on bystander intervention in dangerous and non-dangerous emergencies

Research on bystander intervention has produced a great number of studies showing that the presence of other people in a critical situation reduces the likelihood that an individual will help. As the last systematic review of bystander research was published in 1981 and was not a quantitative meta-analysis in the modern sense, the present meta-analysis updates the knowledge about the bystander effect and its potential moderators. The present work (a) integrates the bystander literature from the 1960s to 2010, (b) provides statistical tests of potential moderators, and (c) presents new theoretical and empirical perspectives on the novel finding of non-negative bystander effects in certain dangerous emergencies as well as situations where bystanders are a source of physical support for the potentially intervening individual. In a fixed effects model, data from over 7,700 participants and 105 independent effect sizes revealed an overall effect size of g = -0.35. The bystander effect was attenuated when situations were perceived as dangerous (compared with non-dangerous), perpetrators were present (compared with non-present), and the costs of intervention were physical (compared with non-physical). This pattern of findings is consistent with the arousal-cost-reward model, which proposes that dangerous emergencies are recognized faster and more clearly as real emergencies, thereby inducing higher levels of arousal and hence more helping. We also identified situations where bystanders provide welcome physical support for the potentially intervening individual and thus reduce the bystander effect, such as when the bystanders were exclusively male, when they were naive rather than passive confederates or only virtually present persons, and when the bystanders were not strangers.     

The Coronary Health Improvement Project (CHIP) for lowering weight and improving psychosocial health

This study extends previous research evaluating the association between the CHIP intervention, change in body weight, and change in psychological health. A randomized controlled health intervention study lasting 4 wk. was used with 348 participants from metropolitan Rockford, Illinois; ages ranged from 24 to 81 yr. Participants were assessed at baseline, 6 wk., and 6 mo. The Beck Depression Inventory (BDI) and three selected psychosocial measures from the SF-36 Health Survey were used. Significantly greater decreases in Body Mass Index (BMI) occurred after 6 wk. and 6 mo. follow-up for the intervention group compared with the control group, with greater decreases for participants in the overweight and obese categories. Significantly greater improvements were observed in BDI scores, role-emotional and social functioning, and mental health throughout follow-up for the intervention group. The greater the decrease in BMI through 6 wk., the better the chance of improved BDI score, role-emotional score, social functioning score, and mental health score, with odds ratios of 1.3 to 1.9. Similar results occurred through 6 mo., except the mental health variable became nonsignificant. These results indicate that the CHIP intervention significantly improved psychological health for at least six months afterwards, in part through its influence on lowering BMI.     

Emotional Dynamics in the Development of Early Adolescent Psychopathology: A One-Year Longitudinal Study

This study examined the role of the level and variability of happiness, anger, anxiety, and sadness in the development of adolescent-reported anxiety disorder symptoms, depressive symptoms, and aggressive behavior in 452 adolescents (250 male) followed from age 13 to 14. Level and between-day variability of emotions were assessed through adolescent report at 3-month intervals across a 1 year period. Level and variability of the four emotions contributed to changes in anxiety disorder and depressive symptoms more consistently than to changes in aggressive behavior. All four emotions were predictive of changes in internalizing problems, while anger played the most prominent role in the development of aggressive behavior. Variability of emotions contributed to changes in anxiety disorder symptoms, while heightened levels of negative emotions and diminished happiness contributed to changes in depression. Results suggested somewhat stronger effects of negative affect on aggressive behavior for females than for males. Results underscore the role of emotion dysregulation in the development of psychopathology.     

ICAT: a computational model for the adaptive control of fixation durations

Eye movements depend on cognitive processes related to visual information processing. Much has been learned about the spatial selection of fixation locations, while the principles governing the temporal control (fixation durations) are less clear. Here, we review current theories for the control of fixation durations in tasks like visual search, scanning, scene perception, and reading and propose a new model for the control of fixation durations. We distinguish two local principles from one global principle of control. First, an autonomous saccade timer initiates saccades after random time intervals (local-I). Second, foveal inhibition permits immediate prolongation of fixation durations by ongoing processing (local-II). Third, saccade timing is adaptive, so that the mean timer value depends on task requirements and fixation history (Global). We demonstrate by numerical simulations that our model qualitatively reproduces patterns of mean fixation durations and fixation duration distributions observed in typical experiments. When combined with assumptions of saccade target selection and oculomotor control, the model accounts for both temporal and spatial aspects of eye movement control in two versions of a visual search task. We conclude that the model provides a promising framework for the control of fixation durations in saccadic tasks.     

Heterogeneity of treatment changes after psychodynamic therapy within a one year follow‐up: A replication study

Naturalistic psychotherapy effect studies commonly report effect sizes for the total sample. However, a previous study of SCL‐90 Global Severity Index (GSI) improvement in a large outpatient sample used a cluster analytic strategy and reported clinical relevant outcome trajectories that could be grouped into early within‐treatment improvement, late improvement in the follow‐up period, and deteriorating patients with slight improvement that was lost at follow‐up. We explore GSI outcome trajectories and clinical significant change in a sample of 320 patients at a public psychiatric outpatient psychodynamic group therapy unit, the majority with anxiety, personality, and mood disorders. The study revealed large discharge and follow‐up effect sizes but more than one third of the patients were without measurable improvement. The major clusters described above were confirmed, and revealed unique clinical and socio‐demographic characteristics. Late improvers, as compared with early improvers, were characterized by anxiety symptoms and lack of network support after controlling for GSI at admission. Similarly, deteriorating patients had longer duration of illness and less favourable social characteristics compared with the other two groups. Early improving patients were less likely to have participated in short‐term groups, and only one third participated in additional treatment compared with more than 69% of the other patients. Severe and socially affected psychiatric patients, and patients with anxiety and agoraphobic symptoms may be less optimally treated in short‐term time limited psychodynamic groups. There is an obvious need for diversity of treatment offers, better integration of psycho‐social treatment components, and long‐term open ended treatment.     

Reward-driven modulation of adaptive control: How prospective monetary gains interact with unpredictable control demands

Shifting attention is an effortful control process and incurs a cost on the cognitive system. Previous research suggests that rewards, such as monetary gains, will selectively enhance the ability to shift attention when this demand for control is explicitly cued. Here, we hypothesized that prospective monetary gains will selectively enhance the ability to shift attention even when control demand is unpredictable and not cued beforehand in a modality shift paradigm. In two experiments we found that target detection was indeed facilitated by reward signals when an unpredictable shift of attention was required. In these crossmodal trials the target stimulus was preceded by an unpredictive stimulus directing attention to the opposite modality (i.e., visual–auditory or auditory–visual). Importantly, there was no reward effect in ipsimodal trials (i.e., visual–visual or auditory–auditory). Furthermore, the absence of the latter effect could not be explained in terms of physical limits in speed of responding. Potential motivation of monetary rewards thus selectively translates into motivational intensity when control (i.e., switching) is demanded in unpredictable ways.