Functional class formation in the context of a foraging task in capuchin monkeys.
Repeated rule reversals can create new stimulus classes in monkeys.
01Research in Context
What this study did
Researchers worked with two capuchin monkeys in a lab foraging game.
The monkeys had to pick the correct picture to get food.
After the monkeys learned the rule, the researchers flipped it.
They kept flipping the rule many times to see if the monkeys would group the pictures into a functional class.
What they found
Both monkeys passed every test.
They treated the two pictures as one team.
This shows repeated rule flips can build new stimulus classes in monkeys.
How this fits with other research
Ellingsen et al. (2014) review shows this kind of learning is the root of language.
da Silva Barros et al. (2013) gives a live demo of that idea in monkeys.
Terrace (1969) also used monkeys and single-case design, but with shock and levers.
Both studies prove monkeys learn fast, yet the tools differ—food versus shock.
Why it matters
You can use reversal drills to build flexible classes with learners who need many exemplars.
Try flipping the S+ and S- across short blocks.
Watch for emergent matching that shows the class has formed.
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02At a glance
03Original abstract
Functional class formation via repeated reversals of simple discriminations was investigated in a foraging task in captive capuchin monkeys (Cebus cf. apella). Two capuchin monkeys were given simultaneous simple discrimination training and reversals with two (Phase 1), four (Phase 2), and six (Phase 3) visual stimuli (wooden boxes) in the context of searching for food in an apparatus. One different kind of food for each potential stimulus class was used as a reinforcer. After repeated functional reversals of two stimulus sets, multiple tests for functional class formation were performed (Phase 4). Evidence of class formation was found in all of the tests. Next, the same monkeys were given simultaneous simple discrimination training with variations of the stimulus locations between sessions (Phase 5). The class-specific reinforcement procedure was suspended. Tests for functional class formation were again performed. Evidence of class formation was found in all tests. The data suggest that some of the procedural difficulties in documenting class formation in nonhumans can be overcome with procedures that take advantage of the natural skills of the subjects.
Journal of the experimental analysis of behavior, 2013 · doi:10.1002/jeab.27