TEMPORAL SEARCH AS A FUNCTION OF THE VARIABILITY OF INTERFOOD INTERVALS

We attempted to determine whether timing theories developed primarily to explain performance in fixed-interval reinforcement schedules are a lso applicable to variable intervals. Groups of rats were trained in l ever boxes on peak procedures with a 30-, 45-, or 60-s interval, or a 30- to 60-s uniform distribution (Experiment 1); a 60-s fixed and 1- t o 121-s uniform distribution between and within animals (Experiment 2) ; and a procedure in which the interval between food and next availabl e food gradually changed from a fixed 60 s to a uniform distribution b etween 0 and 120 s (Experiment 3). In uniform interval schedules rats made lever responses at particular times since food, as measured by th e distribution of food-food intervals, the distribution of postreinfor cement pauses, and the mean response rate as a function of time since food. Qualitative features of this performance are described by a mult iple-oscillator connectionist theory of timing.