Signal detection in a noisy background figure through a limited visual field

Abstract

Pattern perception and eye movement as a function of limited size of effective visual field were examined using noisy background figures. The construction of a stimulus figure and data processing were done by a microcomputer system. The figure exposed to subjects was a random dot pattern with uniform dot density except in one part which had a different dot density. Subjects observed the figure on a CRT by sampling the desired part of a limited area by means of a joystick and video mixing system. The figure was expressed quantitatively by the ratio of dot densities between the two parts, defined as the contrast of the figure.

The higher the contrast the shorter the time to correctly find the different part of the figure. Time was correlated with restricted size of effective visual field. Minimum contrast of the figure just noticeable by subjects was not related to visible window size. Both frequency of saccadic eye movement and averaged single saccadic size were closely related to window size. Resultant total saccadic movements in a task were almost constant no matter what the size of window.

Additional information

Notes on contributors

SUSUMU SAITO

Present address: Department or Industrial Physiology, National Institute of Industrial health, 21-1, Nagao 6, Tama-ku, Kawasaki, 214 Japan.