Conjoint control of performance in conditional discriminations by successive and simultaneous stimuli.
Make hard conditional discriminations easier by pairing large stimulus differences with higher reinforcement rates.
01Research in Context
What this study did
White (1986) looked at how pigeons pick the right key when two kinds of cues show up at once. Birds saw color and line tilt together, then had to choose based on rules that changed each trial.
The team made the cues easy or hard to tell apart. They also changed how often correct choices paid off. The goal was to see if bigger cue differences and richer pay worked together.
What they found
When colors and lines looked very different, birds chose faster and made fewer errors. Big cue gaps gave the clearest stimulus control.
On tough mixes, raising the payoff for the right key helped more than on easy mixes. Reinforcement ratio mattered most when discrimination was hard.
How this fits with other research
Appel (1968) showed that extra practice on simple discriminations later speeds reversal learning. White (1986) adds that cue disparity and payoff can team up during that first learning, not just after overtraining.
Christopher et al. (1991) found free-operant setups beat discrete trials for rat successive discriminations. White (1986) used discrete trials yet still showed strong control, hinting that rich conjoint cues can offset the limits S saw with longer gaps.
Sailor (1971) showed sharper stimulus control shields performance from hunger shifts. G’s tighter control with large cue gaps supports the same shield idea, now under varying payoff rates.
Why it matters
When you build conditional-discrimination programs, stack the deck: make the S+ and S- differ on two senses at once (color plus shape, picture plus location). If you must use close stimuli, boost the reinforcement rate for correct responses to punch through the noise. This two-handle approach—bigger cue gap plus fatter payoff—can cut errors early in training and protect the skill against later motivation swings.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Add a second visual difference (e.g., color border) to near-identiform pictures and reinforce every correct response for the first two sessions.
02At a glance
03Original abstract
In a conditional discrimination, reinforcement of pigeons' responses to pairs of simultaneously presented wavelength stimuli depended on the orientation of white lines superimposed on the wavelengths. Over different conditions in Experiment 1, three wavelength differences were combined with two differences between successively presented line orientations. Measures of stimulus discriminability increased with increases in the difference between both orientation and wavelength stimuli. Conditional-discrimination performance was thus conjointly determined by stimulus disparity in the successive and simultaneous discriminations. In Experiment 2, ratios of rates of reinforcement contingent upon the two categories of correct responses were varied over several conditions for difficult and easy discriminations. Ratios of responses to wavelength pairs were sensitive to variations in the reinforcement ratio to a greater extent for the more difficult orientation discrimination than for the easier orientation discrimination. Performance in the conditional discrimination was therefore determined by the interacting effects of stimulus disparity and the relative rates of reinforcement contingent upon the two correct choices. It was concluded that the effect of temporally distant reinforcement on behavior in a prevailing schedule component is attenuated to an extent that depends on similarity of stimuli that delineate the successive components.
Journal of the experimental analysis of behavior, 1986 · doi:10.1901/jeab.1986.45-161