ABSTRACT
The two theories of abstraction are distinguished by their conflicting accounts of the relationship between perception and thinking, the traditional theory assuming that concepts are formed when particular sensations are organized in thought, whereas the theory affirms that thinking elaborates the forms of organization gained in perception. The two major types of concept shift are intradimensional (ID) and extradimensional (ED) shifts. In both types, there is an initial phase, in which the subject learns a concept to a criterion, and a second phase, in which the subject has to learn a new concept, the cues for which are either along the rewarded dimension of the original concept (ID shift) or along another dimension, usually the one irrelevant in the original learning (ED shift). An alternative conception of discrimination learning is that the organism learns to make two responses, an attentional response to the relevant stimulus dimension followed by an instrumental response.
