Spatial Stimulus-Response Compatibility

Abstract

This chapter describes the different aspects of the spatial stimulus-response (S-R) compatibility. A stimulus dimension is relevant when the required response depends on the value of the stimulus in that dimension, whereas a stimulus dimension is irrelevant if values on it are uncorrelated with the required response. It is found that by combining dimensional overlap with dimensional relevancy, four types of S-R ensembles are obtained. The type-I ensemble occurs when there is no dimensional overlap in either the relevant or the irrelevant dimension. Ensemble type II is characterized by the presence of dimensional overlap in the relevant dimension. It satisfies the condition for obtaining S-R compatibility effects. Most of the studies with Type II ensembles use spatial stimulus and response dimensions. A light is presented in the left or in the right visual field and the subject is required to press either the left or the right key in response. Response time is faster when the imperative stimulus and the response are on the same side than when they are on opposite sides. It is found that in all studies that showed S-R compatibility effects with Type III ensembles, the irrelevant dimension was spatial. The correspondence in space is a particularly powerful way of obtaining an overlap between stimulus set and response set.