THE EFFECTS OF STIMULUS-RESPONSE MAPPING AND IRRELEVANT STIMULUS-RESPONSE AND STIMULUS-STIMULUS OVERLAP IN 4-CHOICE STROOP TASKS WITH SINGLE-CARRIER STIMULI

The purpose of this study was to investigate whether and how stimulus- stimulus (SS) and stimulus-response (SR) consistency and SR congruence effects combine to produce the Stroop effect. Two experiments were co nducted with 4-choice tasks in which SS and SR consistency and SR cong ruence effects were examined in isolation as well as in the Stroop tas k. The experiments were so designed as to remove the confound between SS and SR consistency that is ordinarily found in standard Stroop task s and to pit SS consistency against the logical recoding hypothesis (A . Hedge & N. W.A. Marsh, 1975). The results indicate that SS and SR co nsistency both contribute to the Stroop effect and that they interact. This finding supports models such as the dimensional overlap model (e .g., S. Kornblum & J. W. Lee, 1995) that distinguish between SS and SR overlap. Simulation results from an interactive activation network, m odeled after the dimensional overlap model, provide reasonable fits to the experimental data.