Target-size influences on reaction time with movement time controlled

The variable that affect motor programming time may be studied by changing the nature of the response and measuring the subsequent changes in reaction time (RT). One notion of motor programming suggests that aiming responses with reduced target size and/or increased target amplitude require more "complex" motor programs that require longer RTs. In a series of five experiments which movement time (MT) was experimentally varied target size neither influences RT when the movement amplitude was 2 or 30 cm nor when the target sizes differed by as much as a factor of 16:1. Increasing the movement amplitude from 15 to 30 cm also had no influence on RT. Movement time, however, did affect RT, with 200-msec movements having longer RTs than 120-msec movements. Target size and movement amplitude did not appear to be factors that influence programming time or program complexity.     

Sleep,activity, temperature,and performance: Techniques for long-term monitoring in the mouse

This paper describes a test chamber, a food acquisition task, and a training procedure for the long-term testing of an implanted mouse in a circadian rhythm experiment. For the training phase, a special-purpose controller is provided to a single cage. For the experimental phase, behavioral, electrophysiological, and environmental measures are collected by means of a mini-computer.     

Sex of leader,leader behavior,and subordinate satisfaction

A 2×2×2 factorial design was employed to examine the influence of instructed leadership style, sex of leader, and sex of followers on leader behavior, subordinate satisfaction, and productivity in a simple task. In general, male and female leaders were equally able and equally willing to display autocratic and democratic leadership styles if so instructed. Similarly, leader sex did not have a significant influence on subordinate satisfaction or productivity either by itself or in interaction with leadership style or follower sex.     

Learned helplessness in groups

Group learned helplessness is demonstrated in Experiment I. Groups of 2 tried to turn off noise by their joint action. In the solvable group (S), noise offset was contingent on their sequence of button pushing. In the yoked, unsolvable group (U), noise offset was independent of all sequences of button pushes they produced. In a practice group (O). subjects practiced coordinated sequences of button pushes with their partners, but heard no noise. Later, all 3 groups were tested in pairs in a shuttlebox which required coordinated joint responding to turn off noise. The unsolvable group escaped more poorly than the other 2 groups, paralleling helplessness effects with individuals. Experiment 2 and 3 found no transfer from individual helplessness training to group testing and no transfer from group helplessness training to individual testing. We suggest that the same mechanism, the expectation of response ineffectiveness, may mediate both individual and group learned helplessness.     

Fitting longitudinal reduced-rank regression models by alternating least squares

An alternating least squares method for iteratively fitting the longitudinal reduced-rank regression model is proposed. The method uses ordinary least squares and majorization substeps to estimate the unknown parameters in the system and measurement equations of the model. In an example with cross-sectional data, it is shown how the results conform closely to results from eigenanalysis. Optimal scaling of nominal and ordinal variables is added in a third substep, and illustrated with two examples involving cross-sectional and longitudinal data.Financial support by the Institute for Traffic Safety Research (SWOV) in Leidschendam, The Netherlands is gratefully acknowledged.     

Task dynamics and resource dynamics in the assembly of a coordinated rhythmic activity.

Task dynamics corresponding to rhythmic movements emerge from interactions among dynamical resources composed of the musculature, the link segments, and the nervous and circulatory systems. This article investigated whether perturbations of interlimb coordination might be effect over circulatory and nervous elements. Stiffness of wrist-pendulums oscillated at a common tempo and at 180 degrees relative phase was perturbed through the use of tonic activity about an ankle. Left and right stiffnesses, the common period, and the phase relation all changed. Stiffnesses increased with ankle torque in proportion to the wrist's inertial load. Despite different changes in stiffness at the two wrists, isochrony was preserved. The stability was shown to be consistent with the proportionality of changes in stiffness to the inertial loads. The phase departed from antiphase in proportion to the asymmetry of inertial loads. The size of departures decreased with increasing ankle torque. An account was developed in terms of muscular, circulatory, and nervous functions.