In two experiments, humans received tokens either on a fixed-interval schedule for plunger pulling or various response-nondependent fixed-time schedules ranging from 16 to 140 seconds. Locomotor activity such as walking, shifting weight, or pacing was recorded in quarters of the interreinforcement interval to examine the induced characteristics of that behavior in humans. While performance was variable, several characteristics were present that have counterparts in experiments with nonhumans during periodic schedules of food reinforcement: (a) first quarter rates, and sometimes overall rates, of locomotor activity were greater during intervals that terminated in a visual stimulus and token delivery than those without: (b) overall rates of locomotor activity were greater during fixed-time 16-second schedules than during fixed-time 80- or 140-second schedules; (c) rates of locomotor activity decreased during the interreinforcement intervals; (d) locomotor activity was induced by response-dependent and response-nondependent token delivery. These results showed that the rate and temporal pattern of locomotor activity can be schedule-induced in humans.
Three pigeons were exposed to a fixed-time response independent food-delivery schedule and a live target pigeon restrained in a holder mounted on a spring and microswitch assembly. This common method of recording aggression was compared with a photocell system, and both were evaluated by observation of video-tape recordings. Dependent variables included the number of interfood intervals with an attack, attacks per minute, and attack duration. The photocell proved more reliable than the microswitch and correlated highly with observations of both the number of interfood intervals with an attack for three subjects and attack duration for two. Neither apparatus provided accurate information about the rate of attacks. The microswitch apparatus was not sensitive to changes in the subject's attack topography, while both recording devices were susceptible to activation by responses in the attacking pigeon other than discrete pecks or physical blows. In view of these findings, attacks per minute may not be an appropriate measure of aggression in studies using such devices.
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