Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Dr. Sid Dykstra

Second Advisor

Dr. David O. Lyon

Third Advisor

Dr. Jack Michael


The purpose of the present experiment was to evaluate the stimulus-reinforcer and response-reinforcer relationships in a two-key procedure in which the key that the stimuli appeared on (stimulus key) was separated spatially from the key on which responding was required (constant key) (Hesse, 1984; Keller, 1974). Using pigeons and multiple fixed ratio schedules, the effects of differences in reinforcement duration and reinforcement probability on response latencies to the constant key were compared. Since responding to the stimulus key was not effective in producing reinforcement, any responding that developed to that key was assumed to be due to the stimulus-reinforcer relationships. Differences in FR size and intertrial interval (ITI) length were compared across sessions. The stimuli associated with different reinforcement durations (for two birds) or reinforcement probabilities (for two birds) were displayed on the stimulus key while the responses that produced reinforcement were required on the constant key.

The results showed response latency to be sensitive to differences in reinforcement duration and probability, but only at the higher FR values, which is consistent with the literature showing pre-ratio pause durations in FR schedules to be a function of reinforcement duration, and reinforcement probability, but only with high ratio requirements. Pecks to the stimulus key were sensitive to both reinforcement duration and reinforcement probability more often, but not always, with high FR and short ITI values. These findings suggest that response latency, at least with FR schedules, is more simply conceptualized as pre-ratio pause duration. They also suggest that, at least with pigeons and key pecking, stimulus-reinforcer and response-reinforcer contingencies are usually, if not always, simultaneously present in the same situations and, furthermore, that responding may show sensitivity to the stimulus-reinforcer contingencies irrespective of whether it shows sensitivity to the response-reinforcer contingencies.

Access Setting

Dissertation-Open Access

Included in

Psychology Commons