A Stimulus-Response Compatibility Effect Based On Object Orientation

The current research investigated an orientation-based Stimulus-Response Compatibility (SRC) effect and found that the relationship between the angled orientation of objects (45°/135°) and response attributes (left/right) could facilitate or interfere with the behavioral output. Meanwhile, the research also examined the influence of attention on this SRC effect, and found 1) either the local orientation of a single stimulus or the global orientation of a"perceptual object"grouped by multiple stimuli can induce the orientation-based SRC effect, in which the top-down attentional control plays a vital role; 2) via inducing a corresponding attentional shift, the object orientation automatically activates a spatial response code and finally leads to the generation of the orientation-based SRC effect.In Experiment 1, a Gabor patch, with an angled orientation of either 45°or 135°, was presented at the center of the screen. Participants were asked to respond to its luminance contrast (high/low) by pressing a left or right button. Results revealed that, left-hand responses to 45°-angled targets were much faster than that to 135°-angled targets, whereas right-hand responses showed a reversed pattern. These results well demonstrates an SRC effect based on object angled orientation and further indicates that, angled orientations have implicit spatial representations in cognitive system.In Experiment 2, four flankers were added and a"perceptual object"with a global orientation could be perceived based on perceptual grouping principles. Results showed the global orientation of the"perceptual object"failed to influence the SRC effect based on the local orientation of the single stimulus; Further investigation was conducted in Experiment 3 and showed that, even though flankers were obviously processed, the local-orientation-based SRC effect remained unaffected by the global orientation of the"perceptual object". On the contrary, in Experiment 4, when participants were asked to make a cognitive discrimination on the"perceptual object"(judge the grouping type), an SRC effect based on its global orientation appeared and received no influence by the local orientation of the single stimulus. In brief, the results in Experiment 2 to 4 indicate that, the top-down attentional control plays a decisive role in the generation of the orientation-based SRC effect.Meanwhile, eye-tracking technology was employed in Experiment 4 to track the eye-movements during the cognitive process. Results presented that, more"left"saccades were found when the global orientation was 45°, whereas more"right"saccades were shown when the global orientation was 135°. Considering the previous findings that explicit saccades and implicit attentional shift are highly associated, the eye-tracking results indicate that, the orientation attribute of the stimulus automatically induces an attentional shift which activates a corresponding spatial response code and finally leads to the orientation-based SRC effect.