[Sweating just before the beginning of handgrip performance].

Mental sweating plays an important role to make handgrips smooth. This study examined the relationship between mental sweating and handgrips focusing on the timing of sweat secretion. Five students were instructed to grip a soft ball (nine centimeters diameter) as strongly as possible. Electrodermal and sweating responses were collected from five seconds before to five seconds after the beginning of their handgrips. The results showed that electrodermal responses increased one second before the beginning of the handgrip, and that sweating responses one second after. These results suggest that sweating responses in handgrip performance show a different response pattern from the electrodermal responses. Readiness for handgrip performance required for the maximum might evoked electrodermal responses before the performance, and this process facilitated sweat secretion as the strength of the handgrip reached the maximum.

A mobile device for measuring sensorimotor timing in synchronized tapping.

This paper describes the design of a mobile device for examining sensorimotor timing. Control software installed in this device has facilities for storing time series data of interstimulus onset intervals, intertap onset intervals, and response duration in a comma-delimited file of ASCII text format as well as for running an experiment on synchronization tapping. The device provides a highly convenient way to allow collecting such timing data even in real situations like a kindergarten or a day care center for elderly people, given its mobile property and ease of use.

Freezing degrees of freedom under stress: kinematic evidence of constrained movement strategies.

The present study investigated the effect of psychological stress imposed on movement kinematics in a computer-simulated batting task involving a backward and forward swing of the forearm. The psychological stress was imposed by a mild electric stimulus following poor performance. Fourteen participants hit a moving ball with a horizontal lever and aimed at a distant target with as much accuracy as possible. The kinematic characteristics appearing under stress were delay of movement initiation, small amplitude of movement and low variability of spatial kinematic events between trials. These features were also found in previous studies in which the experimental task required high accuracy. The characteristic kinematics evident in the present study suggested that the movement strategies adopted by the stressed participants were similar to those that appear under high accuracy demand. Moreover, a correlation analysis between the onset times of kinematic events revealed that temporally consistent movements were reproduced under stress. Taken together, the present findings demonstrated that, under psychological stress, movement strategies tend to shift toward the production of more constrained trajectories, as is seen under conditions of high accuracy demand, even though the difficulty of the task itself does not change.