[Coding specificity of orthogonal S-R compatibility].

According to Weeks and Proctor (1990), stimulus-response compatibility effects with vertically oriented stimuli and horizontally oriented responses are a result of coding stimuli and responses with respect to their salient features. The corresponding asymmetries in salience are assumed to hold for both verbal and spatial codes. In contrast, Umiltá (1991) argued that these effects are restricted to verbal coding. Experiment 1 tested the coding specificity of the orthogonal compatibility effect by instructing the S-R mapping either verbally or pictorially, varying the stimulus-response mapping unpredictably within experimental blocks. In Experiment 2, the sequences of trials with changed and unchanged mappings were controlled more extensively. Experiment 3 employed incomplete instructions by explicitly denoting the mapping of one stimulus to one response only. The results of Experiments 1 and 2 are consistent with the assumption of a verbal mediation of the orthogonal compatibility effect under investigation, whereas Experiment 3 shows that it is not verbal coding as such that is responsible for the occurrence of the effect.