Abstract
To clarify the characteristics of eye-head coordination during active head movements, the responses of 10 normal subjects to 10°, 20°, 30°, 40° and 50° target presentations were analyzed quantitatively. The following results were obtained.
1. With the increase of the target angle, the latency of the eye movement increased. On the other hand, that of the head movement decreased. Thus, difference between the latencies of head and eye movements decreased with increasing target angles, e. g. 139 msec at 10° and 50 msec at 40°.
2. The risetimes of the eye and head movements increased with the target angle.
3. The maximum velocity of the eye movement averaged 292°/sec at 10°, increased to 398°/sec at 20°, and remained unchanged thereafter. The maximum velocity of the head movement increased in proportion with the target angle (correlation coefficient r=0.65).
4. The amplitude of the head movement at the time when the eye reached its maximum displacement increased with the target angle, e. g. the head moved through an average of 13% of the target angle at 50°. The sum of eye and head displacement, i. e. gaze, coincide with the target angle at the time of peak eye displacement. This fact indicated that the eye was perfectly fixed upon the target at the end of the eye saccade.
5. At the final resting position, the amplitude of the gaze was exactly the same as the target angle with minimum variance. This proved the accuracy of the technique employed for the recording of eye and head movements.
