Action control: independent effects of memory and monocular viewing on reaching accuracy

Evidence suggests that perceptual networks in the ventral visual pathway are necessary for action control when targets are viewed with only one eye, or when the target must be stored in memory. We tested whether memory-linked (i.e., open-loop versus memory-guided actions) and monocular-linked effects (i.e., binocular versus monocular actions) on action arise from a common mechanism as suggested by evidence from neuropsychology and psychophysics. Participants viewed targets with either one eye or two (vision: monocular versus binocular) and then reached to touch targets in open-loop and memory-guided conditions (condition: open-loop versus 0, 500, 1000, and 1500 ms delays). Results showed that memory-linked and monocular-linked increases in radial and variable movement error were additive (i.e., main effects of vision and condition, but no interaction). This suggests that the two effects on visuomotor control arise from separate mechanisms, in contrast to evidence from psychophysics and neuropsychology suggesting a common underlying mechanism.     

Manual asymmetries in bimanual reaching: the influence of spatial compatibility and visuospatial attention

The goal of the present investigation was to explore the possible expression of hemispheric-specific processing during the planning and execution of a bimanual reaching task. Participants (N = 9) completed 80 bimanual reaching movements (requiring simultaneous, bilateral production of arm movements) to peripherally presented targets while selectively attending to either their left or right hand. Further, targets were presented in spatially compatible (ipsilateral to the aiming limb) and incompatible (contralateral to the aiming limb) response contexts. It was found that the left hand exhibited temporal superiority over the right hand in the response planning phase of bimanual reaching, indicating a left hand/right hemisphere advantage in the preparation of a bimanual response. During response execution, and consistent with the view that interhemispheric processing time (Barthelemy & Boulinguez, 2002) or biomechanical constraints (Carey, Hargreaves, & Goodale, 1996) generate temporal delays, longer movement times were observed in response to spatially incompatible target positions. However, no hemisphere-specific benefit was demonstrated for response execution. Based on these findings, we propose lateralized processing is present at the time of response planning (i.e., left hand/right hemisphere processing advantage); however, lateralized specialization appears to be annulled during dynamic execution of a bimanual reaching task.     

The Neuropsychology of Depression: A Literature Review and Preliminary Model

Neuropsychological research provides a useful framework to study emotional problems, such as depression, and their correlates. This paper reviews several prominent neuropsychological theories. Functional neuroanatomical systems of emotion and depression are reviewed, including those that describe cerebral asymmetries in emotional processing. Following the review, a model that is composed of three neuroanatomical divisions (left frontal, right frontal, and right posterior) and corresponding neuropsychological emotional sequelae within each quadrant is presented. It is proposed that dysfunction in any of these quadrants could lead to symptomatology consistent with a diagnosis of depression. The proposed model combines theories of arousal, lateralization, and functional cerebral space and lends itself to scientific methods of investigation. Accordingly, research, prevention, and treatment programs in accordance with the proposed model may promote an improved understanding of the neuropsychological mechanisms involved in depression.     

Two models of adolescent self-mutilation

Currently little research exists examining the theoretical underpinnings of self-mutilation (SM) in community samples of adolescents. Two models, the hostility and anxiety reduction models, were simultaneously tested in order to determine whether SM in adolescence was characterized by greater feelings of anxiety and hostility. Four hundred and forty students were screened for the presence of SM. Sixty-one students who indicated that they hurt themselves as well as a comparison group of non-SM students completed the Hostility and Direction of Hostility Questionnaire (HDHQ), the Beck Anxiety Inventory (BAI), and an interview. Results indicate support for the hostility model of SM. Students who SM reported significantly more anxiety and more intropunitive and extrapunitive hostility. In addition, prior to self-mutilating feelings of both hostility and anxiety were described. Results are discussed with reference to both theoretical models.     

A semantic memory sentence verification model based on relative judgment theory

A subjective referent model of sentence verification in semantic memory tasks based on the relative judgment theory of Link and Heath (1975), together with the derivation of a discriminability index, are presented in this paper. An attractive feature of the model is its consideration of both error rates and response times (RTs) in the calculation of the discriminability index. The model is also able to account for the frequent finding in semantic memory tasks that error RTs are longer than correct RTs. A partial replication of Experiment 2 of McCloskey and Glucksberg's (1979) sentence verification context effect studies, in which we employed 44 subjects and 28 categories, and controlled for item familiarity, revealed that error RTs were consistently longer than correct RTs--a finding inconsistent with the McCloskey and Glucksberg property comparison model, but in accord with the subjective referent model. An important fortuitous result was the detection of a context effect by the discriminability measure, an effect not detected by the RT data alone. The discriminability measures yielded a near perfect correlation with estimates of the mean step size of the random walk obtained by application of the parameter estimation program FITTRW (Heath, 1983).     

The role of attention in one-handed catching

The present study investigated the contribution of attention to one-handed catching success. A group of skilled (n = 8) and less skilled (n = 9) male subjects were compared in their ability to process secondary task information while executing a primary one-handed catching task. On 40% of the trials, a secondary visual stimulus (SVS) was presented in the peripheral visual field at predetermined times during the flight of the ball. On these trials, the subject was required to complete the one-handed catch and immediately throw the ball at a stationary target. Less skilled subjects made significantly more catching errors under both normal viewing and dual-task processing conditions. The differences were due to errors of positioning rather than grasping. Positioning of the hand appears to require visual attention regardless of skill level, as both skill groups experienced increased difficulty processing secondary task information as the ball approached the catching hand.     

Self-concept Differentiation and Depressive Symptomatology in Children

Self-concept differentiation is the degree to which separate domains of the self-concept are differentiated from one another. Two studies of children's self-reported depressive symptomatology and self-concept differentiation were completed. Study 1 found higher levels of self-concept differentiation associated with greater depressive symptomatology. Study 2 replicated this finding but further revealed a trend for elevated self-concept differentiation to be related to a positive outcome at 5-week follow-up in the depressed sample.     

Evidence for genetic influences on personality from self-reports and informant ratings.

Self-report data on Extraversion (E) and Neuroticism (N), together with ratings by the co-twin, were obtained from a sample of 826 adult female twin pairs ascertained through a population-based twin register. Data were analyzed using a model that allowed for the contributions to personality ratings of the rater's personality (rater bias) as well as of the personality of the person being rated. For E, but not for N, significant rater bias was found, with extraverted respondents tending to underestimate, and introverted respondents tending to overestimate, the Extraversion of their co-twins. Good agreement between self-reports and ratings by the respondent's co-twin was found for both E and N. Substantial genetic influences were found for both personality traits, confirming findings from genetic studies of personality that have relief only on self-reports of respondents.     

Respiratory phase and visual signal detection

Previous studies have implicated respiration as a source of intra-S variation in visual signal detection tasks. In the present study, pneumographic respiration records were obtained on 22 female undergraduates during a visual signal detection task. The analysis of signal detection with respect to respiration phase showed that signals presented during exhalation were detected more frequently than those presented during inhalation. These findings suggest that the intra-S variation in signal detection performance may be partially accounted for by respiratory behavior at the moment of signal presentation.     

Predicting Occupational Status for Non-College-Bound Males

In a follow-up of selected 1957 Wisconsin male high school graduates (N = 2,230), a prediction of occupational status was attempted. Of the 17 independent variables used, 3 emerged as highly significant and valid: post-high school education (p < .001), community of residence (p < .001), and high school grade-point average (p < .01). Two multiple coefficients were obtained (R = .32, F = 42.43, p < .001, and R = .26, F = 24.97, p < .001). Results suggest that family background factors and aspiration levels are not as important in predicting occupational status as are further education and training, high school achievement, and community of orientation in a highly industrialized urban technocracy.