Matching-to-sample performance is better analyzed in terms of a four-term contingency than in terms of a three-term contingency.
Reinforcers are part of the stimulus package, not an extra—plan them like cues.
01Research in Context
What this study did
The team watched pigeons do matching-to-sample tasks. They wanted to know if four pieces, not three, drive the birds’ choices.
Each trial gave a sample, two side pictures, and food after a peck. The extra piece was the food cue that followed the correct choice.
What they found
Bird choices fit a four-term picture better than the old three-term one. The food cue acted like a fourth signal that guided pecks.
In plain words, what happens after the choice is part of the stimulus control story, not just the sample and comparisons.
How this fits with other research
Catania et al. (1972) saw pigeons fail when a fourth picture popped up after three-picture training. Their trouble backs the idea that four parts, not three, run the show.
Campbell (2003) showed old math breaks when food rates swing wide. Adding the fourth term fixes the same gap the new paper spots.
Rodewald (1974) found pigeons learn matching all-at-once, not bit by bit. A four-term view helps explain why sudden jumps appear instead of slow curves.
Why it matters
When you set up conditional-discrimination programs, treat the reinforcer as a taught cue. Show the reward, name it, and vary its place so it joins the stimulus set. This may cut position biases and speed true stimulus control for kids with autism or other learners.
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02At a glance
03Original abstract
Four pigeons performed a simultaneous matching-to-sample (MTS) task involving two samples and two comparisons that differed in their pixel density and luminance. After a long history of reinforcers for correct responses after both samples, 15 conditions arranged either continuous reinforcement of correct responses after Sample 1 and extinction for all responses after Sample 2, or vice versa. The sample after which correct responses were reinforced alternated across successive conditions. The disparity between the samples and the disparity between the comparisons were varied independently across conditions in a quasifactorial design. Contrary to predictions of extant quantitative models, which assume that MTS tasks involve two 3-term contingencies of reinforcement, matching accuracies were not at chance levels in these conditions, comparison-selection ratios differed after the two samples, and effects on matching accuracies of both sample disparity and comparison disparity were observed. These results were, however, consistent with ordinal and sometimes quantitative predictions of Jones' (2003) theory of stimulus and reinforcement effects in MTS tasks. This theory asserts that MTS tasks involve four-term contingencies of reinforcement and that any tendency to select one comparison more often than the other over a set of trials reflects meaningful differences between comparison-discrimination accuracies after the two samples.
Journal of the experimental analysis of behavior, 2013 · doi:10.1002/jeab.32