Exploring handedness asymmetries in the Simon effect

Abstract

Spatially corresponding stimulus-response pairings usually produce shorter reaction times (RTs) than do noncorresponding pairings, even when the spatial dimension of the stimulus is irrelevant to the task. This BSimon effect^for visual stimuli and manual responses is often larger for the stimulus location on the side to which the person's dominant hand is operating. The present study aimed at replicating and examining the nature of this asymmetry. To determine whether the Simon effect asymmetry is a function of the hand distinction or of conceptual spatial codes, performance with left and right manual key-presses was compared to that with vocal responses Bleft^and Bright.^Whether the asymmetric Simon effect pattern is restricted to spatial stimuli was tested by comparing effects obtained with left and right located squares to those found with the centered words Left and Right. The asymmetry was only replicated for the spatial stimulusmanual response Simon task, for which a second experiment showed similar results when the hands and response box were not visible during task performance. The analysis revealed a general dominant-hand RT advantage that similarly adds to both corresponding and non-corresponding trials and is rather independent from the Simon effect. This advantage yields an apparent asymmetry when the data are analyzed as a function of correspondence for each stimulus location because the corresponding and non-corresponding RTs that are compared come from different hands.

Is effector visibility critical for performance asymmetries in the Simon task? Evidence from hand- and foot-press responses

“…The authors of the above-cited studies proposed that the Simon effect asymmetry is due to an attentional bias toward the operating space of the dominant effector, which results in stronger coding of the stimulus location in the visual hemifield. Seibold, Chen, and Proctor (2016) replicated this pattern of results for the location-based Simon effect but not for a wordbased Simon effect, for which the irrelevant location information is conveyed by the centered words left and right (Luo & Proctor, 2019). For right-handers responding to stimuli in physically left and right locations, Seibold et al found faster responses for the right hand than the left hand overall, and provided evidence that the apparent Simon effect asymmetry is an artifact of this difference in response hand/location.…”

“…Reaction time We excluded trials with RTs above 900 ms and below 100 ms (2.5%), as well as error trials (3.4%) for the analysis of the RT, like Seibold et al (2016) and Rubichi and Nicoletti (2006) did. An analysis of variance (ANOVA) was conducted on RT with stimulus location, response location, and effector as within-participants factors on RT.…”

“…With the factors classified in this manner, the stimulus location × response location interaction reflects the Simon effect, which is the performance difference between the corresponding trials and the non-corresponding trials. In addition, the Simon effect asymmetry refers to the difference between the Simon effects (i.e., the stimulus location × response location interaction) for the stimulus locations, which is reflected statistically in the main effect of response location (see Table 1 of Seibold et al, 2016).…”

“…A difference between Wallace's (1972) experiment and that of Seibold et al (2016) is that participants never saw the response keys or their hands placed on them at any stage of Wallace's experiment, whereas in Seibold et al's experiment the participants saw the keys and placed their hands on them prior to the hands being covered up. The difference in results of Wallace and Seibold et al suggests the possibility that participants need to form a visuospatial representation of the response keys and their effectors in order to show the asymmetric Simon effect pattern.…”

“…He conducted an experiment with a location-based Simon task, in which participants who were prevented fromni seeing the hands/keys during task performance did not show the asymmetric pattern, whereas participants tested under conditions in which they could see their hands did show the pattern. However, Seibold et al (2016) reported an experiment in which half the participants performed the similar location-based Simon task with their hands (and the response keys) out of view, and the other half could see their hands and the keys during task performance. The Simon effect asymmetry did not differ in these two conditions, indicating that the lack of visual sensory input for the hand and key locations had no significant influence on the Simon effect asymmetry.…”