Hand writing motion is analyzed theoretically and experimentally from the viewpoint of dynamics. A device is newly developed to measure normal forces acting on a pen exerted by the thumb, forefinger and middle finger respectively to hold the pen while writing letters. The experimental results show that the normal force exerted by the thumb is the largest among the three, and it varies much in accordance with each stroke of Chinese character. Individual differences in the normal forces and the effect of repetition of motion are also examined. Mathematical models of the hand and fingers are established based on an assumption that each segment of the hand and fingers is represented by a rigid body, and equilibrium equations of forces are derived. The equations are solved to estimate the forces and torques acting at individual ioints of the fingers by applying the forces measured and the three dimensional motion data of the fingers obtained photographically.

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The present study intended to find out the perceptible threshold level of human body to a mechanical shock, which has not yet been fully investigated. The subjects for this study were seventy males, aged from 18 to 55. They who sat down straight and unbindingly, were impacted from +Gx and -Gx. The movement of hammer-heads used here was fixed from the region impacted to there. The regions observed include forehead, para-sternal thorax, interscapular thorax and the right gluteal region. The perceptible threshold level at the forehead had the lowest velocity and the largest acceleration. On the contrary, that at the gluteal region had the largest velocity and the lowest acceleration. The impact force at the threshold level showed similar value at each region. The mean value of the impact characteristics (G·S), which is the product of acceleration and its duration, was 0.030 G·S at the forehead and that was 0.063 G·S at the gluteal region. The mean threshold level of all regions in terms of acceleration were 0.610G at 5Hz, 0.855G at 10Hz and 1.153G at 20Hz.

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The purpose of this study is to observe operators on the steering simulator which functions to vary steering angle gains and steering forces (restoring forces, inertial forces and dry friction forces), and to evaluate the influences of the characteristics of steering angle gains and steering forces on the steering angle control.
Control performances, physiological responses (SPL, SPR, EMG) and subjective ratings were observed while operators were acting in persuit trackings.
The followings are the results.
(1) The operator suffers from mental load when steering angle gains are large, and on the contrary he suffers from physical load when they are small.
(2) Control performances become much better at large steering angle by a certain amount of restoring forces.
(3) Control performances tend to be better by a little amount of inertial forces or dry friction forces.

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The present paper deals with the relationship between the number of practices (0, 10, and 50 times) and the anticipatory behavior in violin performance. Data were obtained by recording the movements of four fingers in left hand. The results of cross-correlation coefficient of the duration playing an eight note showed that the internal processes of the skill had three stages depending on the number of practices. The results of moving distances for little finger's actions were as follow; (1) The duration of timing to generate a next action decreased with increasing practice, (2) The anticipatory behavior to press the string was acquired wth a few practices.

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In this paper, learning phenomena are discussed in the framework of possibility. The learning phenomena is generally found in repetitive human tasks or production process in an organization. A curve obtained in the learning phenomena is called a learning curve. The learning curve expresses the decrease of time of per cycle or of the cost per cycle for a large number of repetitive cycles caused by learning effects. This decreasing is natural to interpret possibilistically the learning effects as the possibility of human ability. The Fuzzy regression model is employed to analyze the learning phenomena. This approach enables us to understand two characteristics of a learning effect. One is the trend of the learning effect. The other is the width or amount of possibility at each time. The Fuzzy regression model has been applied to analyze the learning phenomena in data entry jobs using a Japanese wordprocesser.

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This report examines the results of experiments on how noise influences the quality and quantity (and time) of mental work. The experiments consisted of changing a-weighted sound pressuer level (background noise 60, 70, 80, 90dB) during mental work, which consisted of operation activities (addition and subtraction), stamping activity with judgment, and “AMEFURI” erasion. The empirical results are described herein.
(1) Operation activity (addition and subtraction): The error rates and uncompleted work increased when the level of noise increased.
(2) Stamping activity: The stamping error rate and the mean value of time required increased when noise increased.
(3) “AMEFURI” erasion: No influence was noticed.
The above experimental results clarify the following matters. Noise exerts an influence on operation and stamping activities with judgment. On the other hand, noise does not exert an influence on “AMEFURI” erasion. The difference originates in whether or not the auditory sense exists when work is executed.

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This paper concerns human visual reception of information by the picture display. Two levels of human information reception, perception and cognition levels, were considered here and functional difference between these two levels was measured by the psychometric method using the backward masking effect. Kanji character and English word patterns were used for cognitive judgements and Kanji-like and word-like meaningless patterns for perceptual judgements.
As results, it was shown that (1) the cognitive judgement was easier for subjects than the perceptual judgement, (2) difficulty of the perceptual judgement depended upon complexity of patterns and (3) that of cognitive judgement did not so much depend on it.

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