Reversal and nonreversal shifts by cats and rhesus monkeys.

Abstract

Thirty-six experimentally naive cats, 36 experimentally sophisticated cats, and 15 sophisticated rhesus monkeys each learned a reversal, a nonreversal, and a control shift problem. Errors to criterion by the monkeys on reversal and non-reversal shifts did not differ significantly. Both groups of cats made significantly more errors in learning reversal than nonreversal shifts, confirming the predictions of Spence''s single-unit S-R theory of discrimination learning. The results obtained from the monkeys were incompatible with Spence''s single-unit theory, and suggested that simple forms of mediation in problem solving may be observed in nonverbal organisms.