Pausing in chained fixed ratio, fixed interval schedules: Timing overruling the ratio requirement?

Abstract

Seven rats were submitted to chained fixed ratio, fixed interval schedules of reinforcement in an operant conditioning chamber with two response bars. A fixed ratio schedule in one bar produced a discriminative stimulus associated with a 1-min fixed interval schedule of primary reinforcement (water) in the second response bar. In different experimental conditions the ratio requirement was changed from 1, to 3, to 5, and to 8 responses while the fixed interval schedule was kept constant. As expected, increases in the fixed ratio requirement resulted in increases in pausing associated with the fixed ratio schedule, but changed also pauses in the fixed interval schedule. Results were interpreted as the dominance of control by time between primary reinforcement presentations over the fixed interval control by the discriminative stimulus.Keywords: timing, chained schedules, fixed ratio, fixed interval, water, rats.