Probability discrimination indicated by stimulus prediction and reaction speed: Effects of S-R compatibility.

Abstract

Determined the independent effects of stimulus probability and prediction outcome on the discrete 2-choice reaction speed (CRS) of 20 male and 20 female undergraduates for a compatible and an incompatible condition. A symbol occurred at a "left" location on 70% of the initial 150 trials; then the relative frequencies were reversed so that the symbol occurred on the "right" for 70% of 150 presentations. Each trial consisted of Ss' verbal prediction, a stimulus presentation, and Ss' choice response. Group C (compatible) pulled a left-hand trigger to identify "left" and a right-hand trigger to identify "right." The reverse arrangement was used for Group I (incompatible). The degree of probability discrimination reflected by Ss' stimulus predictions and CRSs was greater for Group C than Group I. The marked effects of prediction outcome on CRS did not interact with compatibility. The relative importance of perceptual and response bias in determining effects of CRS are discussed. (18 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)