S-R compatibility: Correspondence among paired elements within stimulus and response codes.

The present paper is the second dealing with the usefulness of the concept of S-R compatibility for behavior theory. This concept concerns the effects of a class of variables that influence task difficulty in experiments in which learning, complexity (amount of information), and discriminability are controlled. Compatibility effects are conceived as resulting from hypothetical information transformation processes (encoding and/or decoding) that intervene between receptor and effector activity. The rate of processing information is assumed to be maximum when these receding processes are at a minimum. The objective of the study of compatibility effects is to discover conditions under which these effects occur, and to establish principles that will permit specification of the nature and difficulty of perceptual-motor tasks in terms of (hypothetical) intervening information transformation processes. Such processes must be inferred, just as do constructs such as habit strength, from measures of performance obtained in appropriate experiments. The type of experiment of greatest interest for the present purpose is one in which it is possible to measure the rate of information trans-