Acquisition of prerequisites to conservation by macaques.

Through a progressive series of learning sets, two rhesus macaques were trained to discriminate transformations that produce change of substance from other transformations and manipulations. Several tests were administered to assess the generalization of this discrimination to a variety of objects and shapes and to assess the effects, if any, of size cues, experimenter familiarity, and various methods to problem presentation. After training was completed, performance was not greatly affected by differences in problems and presentations. The results of these experiments suggest that monkeys can acquire this prerequisite for substance conservation as a result of learning set training.