Task-dependent compensatory responses to perturbations applied during rhythmic movements in humans

Modulation of the responses to perturbation applied during different phases of three rhythmic movements in humans-running, cycling, and hopping-was studied. The perturbation was an electrical stimulus. The results showed gating and modulation of the responses in both ipsi- and contralateral limb muscles. The responses during running and cycling were only excitatory in nature, while during hopping an inhibitory response was observed. These responses were not correlated with the normal activity during the movement. The latency of the response in general was not altered for different stimulation phases. The alterations in the step cycle demonstrated overt behavioral changes due to the responses. There were differences between the responses observed during these movements and walking. In running, the major adaptation to perturbations appears to be in the contralateral side as seen in the changes in the step cycle. During cycling (except for one phase) and hopping, the same set of muscles was activated in response to perturbation. This represents a simplifying strategy in response organization. The dependency of the response on the task characteristics, postural stability requirement, and external constraints imposed on the subject is discussed. These studies provide insights into task-dependent strategies adopted by the nervous system to meet unexpected perturbation during rhythmic movements in humans.     

Psychometric characteristics and dimensionality of a Persian version of Rosenberg Self-esteem Scale

The Rosenberg Self-esteem scale was translated into Persian and 12 Iranian bilingual judges confirmed the soundness of translation. The psychometric properties of the Persian version of Rosenberg Self-esteem Scale were studied in two samples of Iranian college students separately. Sample I consisted of 232 Iranian students in American universities, and Sample II comprised 305 Iranian students in Iranian universities. Criterion measures of loneliness, depression, anxiety, neuroticism, psychoticism, misanthropy, locus of control, tendency to dissimulate, and measures of relationship with parents, peers, and academic achievement were obtained. Item-total score correlations and alpha reliabilities supported the internal consistency of the scale. Test-retest reliabilities indicated the stability of the scores, and correlations between scores of the scale, and criterion measures supported the concurrent validity of the Rosenberg scale. Factor analysis of the Rosenberg scores confirmed the unidimensionality of the scale.     

Interhemispheric integration of compound nouns: effects of stimulus arrangement and mode of presentation

Normal subjects had to name German compound nouns which were presented tachistoscopically. The compound nouns were displayed either unilaterally to the left or right visual field or bilaterally with one element to each visual field. In the bilateral condition a distinction was made as to whether familiar or unfamiliar arrangement of the elements was used. Representation in print was compared with pictorial representation of the compound nouns. A right visual-field superiority was observed with printed representation, but no laterality effects with pictorial representation. Bilateral processing was superior to unilateral processing. Within the bilateral conditions, the familiar arrangement of the elements yielded a significantly better performance than unfamiliar arrangement. This difference can be explained by reading habits and/or by different styles of interhemispheric integration.     

Differential visual field-interhemispheric transfer: can it explain sex and handedness differences in lateralization?

104 men and women were tested for visual field-hemispheric transfer of spatial information on a dot-localization task. Right-handed subjects showed significant improvement when stimuli were presented to the left visual field of the right hemisphere (LVF-RH) after practice on the same task presented to the right visual field of the left hemisphere (RVF-LH) first. No improvement was found when the task was presented in the reverse order (LVF-RH first followed by RVF-LH). It was concluded that, for right-handers, transfer of spatial information to the right hemisphere is facilitated while transfer to the left hemisphere is inhibited. Left-handed subjects demonstrated no significant improvement in either condition, suggesting inhibition or lack of transfer of spatial information in either direction. No sex differences were found in either right-handed or left-handed subjects. The findings suggest that there may be different mechanisms underlying the similarities in functional lateralization of women and left-handers.     

Handedness and dementia

Some researchers have speculated that left-hand dominance is more prevalent among patients suffering from dementia of the Alzheimer's type which began prior to age 65 yr. and that, in those patients, the disease runs a more rapid course. In the present study, seven left-handed dementia patients were matched with seven right-handed dementia patients on the basis of age and years of education and were compared with regard to neuropsychological compromise. While the left-handed group was somewhat more impaired than the right-handed subjects, the difference between the two groups was not statistically significant.     

A FIELD STUDY OF APPLICANT REACTIONS TO EMPLOYMENT OPPORTUNITIES: DOES THE RECRUITER MAKE A DIFFERENCE?

Previous cross-sectional field and laboratory research has provided mixed results as to whether recruiter characteristics and behaviors influence applicant reactions to employment opportunities. The present research was conducted to examine the effect of recruiter characteristics using a pre-post study design in a naturally occurring setting. In addition, the effects of several potential moderators on recruiter influence were tested. Results indicated that recruiter characteristics had an impact on perceived job attributes, regard for job and company, and likelihood of joining the company. There was little evidence that the effect of recruiter characteristics was moderated by selected applicant, job, or interviewer variables.     

Specific temporal-lobe signs and enhanced delayed cross-modal matching performance

Structural damage to the amygdala severely retards delayed cross-modal (tactile-to-sight) matching in primates. Conversely, we hypothesized that people who display signs suggestive of specific temporal lobe lability should show enhanced delayed cross-modal matching performance. The hypothesis was supported. In a single experiment involving 25 subjects, significant negative correlations obtained between the numbers of errors on the cross-modal matching task and numbers of affirmative responses within clusters of items that contained themes of meaningfulness, religious beliefs or ictal, complex partial epileptic (limbic) states. On the other hand, the numbers of errors were not significantly correlated with either clusters of control items or items that are presumed to reflect the function of other temporal-lobe structures. Both matching and questionnaire data were collected under double-blind conditions.     

The Effects of Flavor-Aversion Learning on Instrumental Performance

Two experiments investigated the role of lithium-mediated environmental conditioning on instrumental performance. Experiment 1 demonstrated that a novel taste consumed in one arm of a T maze prior to lithium-induced toxicosis reduced performance in this environment whereas similar aversions conditioned in the home cage failed to alter maze performance. Experiment 2 showed that maze performance in a straight alleyway was decremented during extinction only in a group that actually traversed the alley prior to drinking saccharin and receiving lithium injections. This demonstrated that the instrumental decrement observed in Experiment 1 was due not only to the presence of an unpalatable flavor in the goalbox during the test.