McDevitt, M. A. & Williams, B. A. (2003).
Arousal, changeover responses, and preference in concurrent
schedules.
Journal of Experimental Analysis of Behavior,
80, 261-272.
Pigeons were trained on multiple schedules that provided concurrent
reinforcement in each of two components. In Experiment 1, one component
consisted of a variable-interval (VI) 40-s schedule presented with a VI 20-s
schedule, and the other a VI 40-s schedule presented with a VI 80-s schedule.
After extended training, probe tests measured preference between the stimuli
associated with the two 40-s schedules. Probe tests replicated the results of
Belke (1992) that showed preference for the 40-s schedule that had been paired
with the 80-s schedule. In a second condition, the overall reinforcer rate
provided by the two components was equated by adding a signaled VI schedule to
the component with the lower reinforcer rate. Probe results were unchanged.
In Experiment 2, pigeons were trained on alternating concurrent VI 30-s VI 60-s
schedules. One schedule provided 2-s access to food and the other provided 6-s
access. The larger reinforcer magnitude produced higher response rates and was
preferred on probe trials. Rate of changeover responding, however, did not
differ as a function of reinforcer magnitude. The present results demonstrate
that preference on probe trials is not a simple reflection of the pattern of
changeover behavior established during training.
Key words: arousal, concurrent schedules, changeover behavior,
reinforcer duration, preference, key peck, pigeons