Concurrent schedule control of human visual target fixations.

Operant conditioning techniques were applied to the study of how target fixations are controlled by the probability of signal occurrence. In a standard vigilance setting, gaze at three illuminable volt meters was monitored by a Mackworth television eye camera with automatic recording capability. Gaze at a given meter produced illumination of the meter, and signals (deflections of the needle on the meter) were scheduled as intermittent consequences of this response. Target fixations were thus placed under the control of concurrent variable-ratio, differential-reinforcement-of-low-rate, and fixed-interval schedules in normal adult volunteers.