The locus of adaptation to altered gain in aimed movements

Altered gain settings cause a mismatch between the actual movement amplitude across the surface and the distance covered on a real time visual display. The present study pursued three objectives of how adaptation to altered gain affects aimed motor behavior. First, we replicated findings of an earlier study reporting a negative linear relation between gain and both target acquisition time and end-point variability. This means that our data do not agree with the classic U-shaped relation between gain and acquisition time. Second, our results proved to be robust when we manipulated movement difficulty by varying target distance. And third, dividing a movement into four successive sections on the basis of key kinematic events revealed the locus of the adaptation to altered gain within movement execution. Time differences between gain conditions proved to start at a very early part of the movement, but appeared to be absent in the final movement section. In contrast, differences between gain conditions regarding the use of online feedback were also present in the last part of the movement during which the final target approach takes place.     

Overwriting of phonemic features in serial recall

We tested two explanations of the phonological similarity effect in verbal short-term memory: The confusion hypothesis assumes that serial positions of similar items are confused. The overwriting hypothesis states that similar items share feature representations, which are overwritten. Participants memorised a phonologically dissimilar list of CVC-trigrams (Experiment 1) or words (Experiment 2 and 3) for serial recall. In the retention interval they read aloud other items. The material of the distractor task jointly overlapped one item of the memory list. The recall of this item was impaired, and the effect was not based on intrusions from the distractor task alone. The results provide evidence for feature overwriting as one potential mechanism contributing to the phonological similarity effect.     

Comparison of fundus autofluorescence and minimum-motion measurements of macular pigment distribution profiles derived from identical retinal areas

The optical density of macular pigment was measured at twelve retinal locations in ten subjects by minimum motion photometry, comparing 460 nm with 580 nm or 550 nm. Fundus autofluorescence images were obtained for the same subjects with a scanning laser ophthalmoscope. Optical density was computed from mean calibrated grey-scale values for a central circular field and for annular segments, identical to areas tested psychophysically, and for complete annuli. Psychophysical assessments of optical density were similar irrespective of whether 550 nm or 580 nm was used. Optical density values derived psychophysically showed a linear correlation with assessments based on identical sampled areas of annular segments (slope = 0.98, r2 = 0.97) or complete annuli (slope = 0.89, r2 = 0.96) in autofluorescence images.     

Context in selection of men and women in hiring decisions: gender composition of the applicant pool

The hypothesis that the sex composition of an applicant pool affects the hiring probabilities of individual job applicants was tested using gender-distinctive information on accepted and rejected job applicants in The Netherlands. The evidence supports this hypothesis, although the effect sizes are moderate. Both men and women have a lower probability of being hired when the applicant pool contains fewer applicants from their own sex.     

Relationships of Functional Flexibility with Individual and Work Factors

To investigate how functional flexibility is related to demographics, personality traits, and work perceptions, 250 employees of a large Dutch passenger transport firm filled out a written questionnaire. Two dimensions of functional flexibility were discerned: willingness and ability to be flexible. Analysis of variance showed the support staff and managers were higher on willingness and ability to be flexible than workers. Hierarchic regression analysis showed that willingness to be flexible was positively related to initiative and trust in management, and was negatively related to age and task formalization. Ability to be flexible was positively related to general self-efficacy and initiative, and was negatively related to task formalization. It was concluded that willingness to be flexible depends on fair treatment and freedom provided by their organization and that ability to be flexible is part of the development of general self-efficacy.     

Rewarding leadership and fair procedures as determinants of self-esteem

In the present research, the authors examined the effect of procedural fairness and rewarding leadership style on an important variable for employees: self-esteem. The authors predicted that procedural fairness would positively influence people's reported self-esteem if the leader adopted a style of rewarding behavior for a job well done. Results from a scenario experiment, a laboratory experiment, and an organizational survey indeed show that procedural fairness and rewarding leadership style interacted to influence followers' self-esteem, such that the positive relationship between procedural fairness and self-esteem was more pronounced when the leadership style was high in rewarding behavior. Implications in terms of integrating the leadership and procedural fairness literature are discussed.     

Lack of the metabotropic glutamate receptor subtype 7 selectively modulates Theta rhythm and working memory

Metabotropic glutamate receptors (mGluRs) are known to play a role in synaptic plasticity and learning. We have previously shown that mGluR7 deletion in mice produces a selective working memory (WM) impairment, while other types of memory such as reference memory remain unaffected. Since WM has been associated with Theta activity (6-12 Hz) in EEGs, and since EEG abnormalities have been observed in these mice before, we studied the effect of mGluR7 gene ablation on EEG activity in the hippocampus, in particular in the Theta range, during performance of a WM task. In an eight-arm maze with four arms baited, mGluR7 knock-out (KO) and wild-type mice committed the same number of reference memory errors, whereas KOs committed more WM errors. While performing the task, KO mice showed substantially higher Theta amplitudes, and the ratio of Theta to overall EEG power was much increased. No change was seen in the Delta (0-5 Hz), or Gamma (30-40 Hz) EEG bands compared with controls. When recording EEGs during periods of rest in the home cages, no difference was seen between groups. These findings suggest that mGluR7 is important for modulation and control of Theta activity. Since only WM was affected, and only the Theta range of EEG activity was altered, these results show a correlation between Theta rhythm and WM performance, and therefore support the concept that Theta activity in the hippocampus is involved in WM storage.     

The effect of conscious control on handwriting in children with attention deficit hyperactivity disorder

Two experiments were performed regarding the effect of conscious control on handwriting fluency in healthy adults and ADHD children. First, 26 healthy students were asked to write a sentence under different conditions. The results indicate that automated handwriting movements are independent from visual feedback. Second, the writing performance of 12 children with ADHD was examined on their usual medication with methylphenidate and under placebo. In comparison to placebo, medication with methylphenidate resulted in a reduced fluency of handwriting. Automated handwriting movements could be elicited in children with ADHD on medication. The results suggest that both visual and mental control of handwriting movements affect the automation of handwriting movements. Furthermore, a simple training procedure was designed and performed in a case study of a boy with ADHD.     

An evaluation of the Tripartite Influence Model of body dissatisfaction and eating disturbance with adolescent girls

The Tripartite Influence Model of body image and eating disturbance proposes that three formative influences (peer, parents, and media) affect body image and eating problems through two mediational mechanisms: internalization of the thin-ideal and appearance comparison processes. The current study evaluated this model in a sample of 325 sixth through eighth grade girls. Simple path analyses indicated that internalization and comparison fully mediated the relationship between parental influence and body dissatisfaction and partially mediated the relationship between peer influence and body dissatisfaction. Additionally, internalization and comparison partially mediated the relationship between media influence and body dissatisfaction. Six a priori SEM models based on the full Tripartite Influence Model were also evaluated. A resulting model was found to be an adequate fit to the data, supporting the viability of the Tripartite Model as a useful framework for understanding processes that may predispose young women to develop body image disturbances and eating dysfunction.     

Concurrent validity of the DSM-IV scales Affective Problems and Anxiety Problems of the Youth Self-Report

This study investigated the concurrent validity of the DSM-IV scales Anxiety Problems and Affective Problems of the Youth Self-Report (YSR) in a community sample of Dutch young adolescents aged 10-12 years. We first examined the extent to which the YSR/DSM-IV scales reflect symptoms of DSM-IV anxiety disorders and DSM-IV Major Depressive Disorder, assessed with the Revised Child Anxiety and Depression Scale (RCADS). Second, we examined whether the association between the YSR/DSM-IV scales and the RCADS scales was stronger than the association between the empirically derived YSR narrow-band scales Anxious/Depressed and Withdrawn and the same RCADS scales. Results showed that the YSR/DSM-IV scale Affective Problems had a stronger association with symptoms of DSM-IV Major Depressive Disorder than the YSR narrow-band scales Withdrawn and Anxious/Depressed. However, the YSR/DSM-IV scale Anxiety Problems had a weaker association with symptoms of DSM-IV anxiety disorders, compared to the YSR narrow-band scale Anxious/Depressed. It was concluded that the construction of the DSM-IV scales improved the correspondence with DSM-IV Major Depressive Disorder, but not with DSM-IV anxiety disorders.