Davison, M. & Elliffe, D. (2010).
Divided stimulus control: A replication and a quantitative model.
Journal of the Experimental Analysis of Behavior, 94, 13-23.
Four pigeons were trained on a conditional discrimination. The conditional stimuli were compounds of pairs of stimuli from two different dimensions, fast versus slow
cycles of red or green stimuli, and short- versus long-duration presentations of these cycles. Across conditions, the probability of reinforcers for correctly responding
to each dimension was varied from 0 to 1. Discriminability, measured by log d, for stimuli on a dimension increased as the relative frequency of reinforcers for that
dimension increased, replicating the results of Shahan and Podlesnik -2006). Two further conditions showed that discriminability between stimuli on each dimension was
unaffected by whether the stimuli on the other dimension varied or were constant. Finally, maximal discriminability was unchanged in a redundant-relevant cues condition
in which either of the stimuli comprising a compound signaled the same correct response. Davison and Nevin's -1999) model provided an excellent quantitative account of
the effect of relative reinforcer frequency on discriminability, and thus of the way in which divided stimulus control is itself controlled by relative reinforcement.
Key words: conditional discrimination, compound stimuli, relative reinforcers, stimulus control, key peck, pigeons