Toshiteru Hatayama

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.

Improvement of nonverbal behaviour in Japanese female perfume‐wearers

The present study addressed the issue of whether people who use perfume improve their “visual” interpersonal impression. This expectation comes from the possibility that those who wear perfume may modify their nonverbal behaviour through positive mood changes generated by the pleasant odour of perfume or through an increase of public self‐consciousness. Thirty‐one Japanese females were assigned to either a perfume or a no‐perfume group. A screening test held in advance confirmed that all the participants in the perfume group preferred the smell of the perfume used in this study. They participated in an interview and answered questions asked by a female confederate. In the middle of the interview, the interviewees in the perfume group put on the perfume. The improvement of their nonverbal behaviour in the latter half of the interview was evaluated by 18 neutral observers, who watched silent video clips of the interviews. The observers were not informed that some of the interviewees used perfume. The result...

An examination by forearm EMG on pain reaction time to radiant heat

The present study was done to estimate rise in skin temperature during a pain reaction time (pain RT) as a means of investigating why a pricking pain threshold, produced by thermal stimulation using time method, often increases during repeated measurements. The pain RT, or the time-delay between occurrence of pain sensation and a subsequent motor response, was measured by making EMG recording on a forearm. The radiant heat stimuli were three, 200, 300, and 350 mcal/sec./cm2, each of which was given through a round radiation window of an algesiometer head. Analysis showed that the pain RTs would be too short to explain higher pain thresholds often found using the time method.

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.