A combined process in determining the direction and size of the Simon effect with wheel -rotation responses

Dongyuan Wang, Purdue University


The Simon effect refers to an advantage when a stimulus' spatial location corresponds to that of its response, even though stimulus location is irrelevant to the task. The Simon effect is typically attributed to spatial coding of the stimuli and responses. It is assumed that a stimulus automatically activates its spatially corresponding response, with this activation facilitating responding when that response is correct and interfering when it is not. Though the instructed action effect is usually produced in response to a stimulus, multiple irrelevant/unintended action effects associated with other response features may be activated as well, and the spatial codes of these actions can be in opposition. ^ Five experiments were conducted to investigate how irrelevant action effects influence response selection with a wheel in an auditory Simon task. Experiment 1 showed that a cursor triggered by the wheel response did not yield an overall Simon effect even with instructions emphasizing the cursor. Experiment 2 indicated that experience with a controlled cursor yielded an overall Simon effect even when the cursor was triggered by the wheel response, suggesting that subjects coded their responses in terms of cursor movement. A combined action effect hypothesis was proposed to account for the size change of the Simon effect with an opposite action effect. ^ Experiments 3, 4, and 5 were designed to test the hypothesis that the combined result of the action effects (relevant hand-movement and irrelevant cursor-movement) determines the direction and the size of the Simon effect. In Experiment 3, all six sequences of three display conditions were used, and a carryover effect from the controlled cursor to the triggered cursor was found. Thus, a sequence with increasing cursor involvement (no-cursor, triggered-cursor, and controlled-cursor) was selected for Experiments 4 and 5. The Simon effect was reduced in both experiments when there was a conflicting action effect. In Experiment 4, the reduction was due in part to individual differences in response-selection strategy. However, in Experiment 5, the reduction was due to the combination of conflicting action effects, supporting the hypothesis that this combination determines the direction and size of the Simon effect. ^




Major Professors: Robert W. Proctor, Purdue University, David F. Pick, Purdue University.

Subject Area

Psychology, Experimental|Psychology, Cognitive

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