Pigeons produced food on a fixed‐ratio schedule by pecking at one key, and an SΔperiod by pecking at a second (switching) key. Switching behavior was examined as a function of (a) size of the fixed ratio, (b) whether the SΔwas of fixed duration or could be determined by the bird, (c) the introduction of a novel food SD, (d) extinction of food responding, and (e) the stimuli associated with the SDand SΔconditions. No monotonic relationship was obtained between ratio size and switching behavior. Switching behavior was, however, influenced by many variables. The results suggest that an interpretation of switching behavior in terms of its being reinforced by the removal of aversive conditions, is open to considerable ques