Colour Correspondence Effects between Controlled Objects and Targets

The effect of irrelevant response dimension on stimulus response compatibility

The well-known Stroop, Simon, and Eriksen flanker effects reflect the influence of an irrelevant dimension of a stimulus on task performance. In contrast, this study investigated the effect of an irrelevant (color) dimension of a response on performance. In Experiment 1, participants performed a color-discrimination Simon task with left and right responses. The novel feature of the experiment was that two-colored labels were presented at the bottom of the display, on the left and right side respectively, which were irrelevant to the task and had nothing to do with response keys. The results revealed a Color Compatibility effect. Participants responded faster and more accurately when the color of the label appearing on the same side (left or right) as the correct response matched the color of the stimulus than when it did not. Experiment 2A replicated the Color Compatibility effect. Experiment 2B showed that the Color Compatibility effect in reaction times disappeared when color was irrelevant to both the stimulus and the response. The results suggest that the presence of an irrelevant color dimension at response may result in a stimulus-response compatibility (SRC) effect as long as the color is represented in working memory. These studies have implications for the dimensional overlap model and the broader understanding of stimulus-response compatibility effects.

Approach and avoidance movements are unaffected by cognitive conflict: a comparison of the Simon effect and stimulus-response compatibility

Participants in this study reached from central fixation to a lateral position that either contained or was opposite to the stimulus. Cognitive conflict was induced when the stimulus and response directions did not correspond. In the Simon task, the response direction was cued by the color of the lateral stimulus, and corresponding and noncorresponding trials varied randomly in the same block of trials, resulting in high uncertainty and long reaction times (RTs). In the stimulus-response compatibility (SRC) task, participants reached toward or away from the stimulus in separate blocks of trials, resulting in low uncertainty and short RTs. In the SRC task, cognitive conflict in noncorresponding trials slowed down RTs but hardly affected reach trajectories. In the Simon task, both RTs and reach trajectories were strongly influenced by stimulus-response correspondence. Despite the overall longer RTs in the Simon task, reaches were less direct and deviated toward the stimulus in noncorresponding trials. Thus, cognitive conflict was resolved before movement initiation in the SRC task, whereas it leaked into movement execution in the Simon task. Current theories of the Simon effect, such as the gating of response activation or response code decay, are inconsistent with our results. We propose that the SRC task was decomposed as approaching and avoiding the stimulus, which is sustained by stereotyped visuomotor routines. With complex stimulus-response relationships (Simon task), responses had to be coded as leftward and rightward, with more uncertainty about how to execute the action. This uncertainty permitted cognitive conflict to leak into the movement execution.