Monkeys were given 288 object-discrimination problems; after reaching criterion on each, a reversal problem was given, with the discriminanda presented in a new orientation. On the original learning-set formation, spider monkeys performed better than cebus monkeys, which were in turn better than cynamolgus monkeys, and the groups showed the same relative ability to reverse in response to shifts in spatial presentation. (PsycINFO Database Record (c) 2006 APA, all rights reserved)