Enhanced spatial stimulus–response mapping near the hands: The Simon effect is modulated by hand-stimulus proximity.

Abstract

Emerging evidence has revealed that visual processing of objects near the hands is altered. The present study shows that the visuomotor Simon effect when the hands are proximal to stimuli is greater than that observed when the hands are far from stimuli, thereby indicating stronger spatial stimulus-response mapping near the hands. The visuomotor Simon effect is robustly enhanced near the hands even when hand visibility and stimulus-response axis-similarity are controlled. However, the semantic Simon effect with location words is not modulated by hand-stimulus proximity. Thus, consistent with the dimensional overlap model and the known features of the bimodal visuotactile neurons, hand-stimulus proximity enhances spatial stimulus-response mapping but has no effect on semantic processing of location words.

Task demands determine hand posture bias on conflict processing in a Simon task

“…In line with these findings, Wang, Du, He, and Zhang (2014) found facilitated low-level sensory processing mechanisms in a Simon (1990) task when the hands were close to the stimuli. In their experiment, participants responded with left or right buttonpresses to the identity (i.e., color) of stimuli presented unpredictably on either the left or the right of the screen.…”

“…To test this assumption, in Experiment 1 we implemented a version of the Simon task in which participants were not required to categorize low-level perceptual features (e.g., color) as in Wang et al (2014), but to semantically categorize left-or right-presented digits as being either smaller or larger than 5 (Fischer, Dreisbach, & Goschke, 2008;Fischer, Plessow, Dreisbach, & Goschke, 2014). Thus, in order to correctly perform the task, the semantic size information needed to be accessed for each digit.…”

“…Note that a combination of multiple (e.g., S-S and S-R) conflict sources is not uncommon in typical conflict paradigms (e.g., the Stroop task). As a consequence, and important for the aim of the present study, the number Simon task involves much more complex cognitive processing of the stimuli than the low-level perceptual color discrimination in the study of Wang et al (2014).…”

“…In Simon tasks with low-level perceptual feature discriminations, the Simon effects increase in hands-close conditions, due to enhanced spatial processing (Wang et al, 2014). If increased cognitive processing demands were to emphasize an engagement of cognitive control for stimulus processing close to the hands, a Simon task should yield reduced effects-that is, the opposite finding to that reported by Wang et al More specifically, any manipulation that exhibited increased engagement of cognitive control in the Simon task should predict reduced Simon effects due to enhanced target (indirect-route) processing-and thus, increased control over direct-route processing of the irrelevant spatial dimension (e.g., Stürmer, Leuthold, Soetens, Schröter, & Sommer, 2002).…”

“…On the one side, studies showing facilitating effects of hand proximity often require target detection and stimulus categorization on the basis of low-level perceptual features (e.g., Reed et al, 2006;Wang et al, 2014). In contrast, tasks that involved more complex (e.g., semantic) cognitive stimulus processing (e.g., Davoli et al, 2010;Weidler & Abrams, 2014) have been associated with increased engagement of cognitive control for items appearing at a position close to the hand.…”