Establishing Functional Classes In A Chimpanzee (Pan troglodytes) With A Two-item Sequential-Responding Procedure.
Rapid within-session reversals, not slow across-day ones, created flexible stimulus classes in a chimp.
01Research in Context
What this study did
One adult chimpanzee played a two-item sequence game on a touch screen. She had to tap two pictures in the correct order to earn apple pieces.
The twist: the correct order flipped several times inside the same session. After a few reversals, new pairs appeared. The team watched if the ape treated the new pairs the same way as the old ones.
What they found
The chimp quickly learned each reversal and then treated brand-new pairs the same way. Her choices showed she had built two 'functional classes'—Group A always came first, Group B second.
Only within-session reversals created this transfer. When earlier tests spaced reversals across days, classes never formed.
How this fits with other research
Busch et al. (2010) showed pigeons can match a picture to itself after special training. The chimp work moves the same idea up the primate ladder and adds a timing rule: rapid reversals matter.
Allan et al. (1994) built three- and four-member classes with adults with autism. Both studies prove humans and non-humans can form classes, but the chimp paper pinpoints the need for quick, not slow, rule changes.
Bacon-Prue et al. (1980) found pigeons forget two-item sequences after only two seconds. The chimp kept the rule across many trials, showing class formation, not just short-term memory.
Why it matters
If you want flexible stimulus classes—whether with learners with autism or typical preschoolers—flip the rules fast within the same lesson. Try three quick reversals of a matching game before you introduce new examples. The speed, not the species, seems to be the secret sauce.
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02At a glance
03Original abstract
A 9‐year‐old female chimpanzee was trained on a two‐item sequential‐responding task. Attempts were made with successive‐reversal training to establish functional classes. In Experiment 1, the subject was exposed to between‐session successive‐reversal training in which one of two pairs of stimuli was reversed, and transfer of reversal responding to the other pair was tested with nonreinforcement probe trials. She did not show transfer during the course of reversals. Stimulus control established in the original training was maintained on nonreinforcement probe trials. In Experiment 2, within‐session reversals were introduced. She showed transfer from the initially reversed pair to the other. The results were consistent with Vaughan's (1988) results with pigeons on successive discriminations, which indicated the formation of functional classes. In Experiment 3, crossover and wild‐card tests were conducted to clarify the stimulus control of sequential responding. The results suggested that the sequential responding was controlled only by the first stimulus of each pair. To establish control by both first and second stimuli, trial‐unique stimuli or wild cards were substituted for one of the items of the lists in Experiment 4. Further transfer tests, in which stimuli for the two new pairs appeared, were also given to the subject. She successfully responded to these two merged lists and reversed the order as the result of reversal training.
Journal of the experimental analysis of behavior, 1999 · doi:10.1901/jeab.1999.72-57