Flanker and Simon effects interact at the response selection stage

Abstract

The present study aimed at investigating the processing stage underlying stimulus-stimulus (S-S) congruency effects by examining the relation of a particular type of congruency effect (i.e., the flanker effect) with a stimulus-response (S-R) spatial correspondence effect (i.e., the Simon effect). Experiment 1 used a unilateral flanker task in which the flanker also acted as a Simon-like accessory stimulus. Results showed a significant S-S Congruency x S-R Correspondence interaction: An advantage for flanker-response spatially corresponding trials was observed in target-flanker congruent conditions, whereas, in incongruent conditions, there was a noncorresponding trials' advantage. The analysis of the temporal trend of the correspondence effects ruled out a temporal-overlap account for the observed interaction. Moreover, results of Experiment 2, in which the flanker did not belong to the target set, demonstrated that this interaction cannot be attributed to perceptual grouping of the target-flanker pairs and referential coding of the target with respect to the flanker in the congruent and incongruent conditions, respectively. Taken together, these findings are consistent with a response selection account of congruency effects: Both the position and the task-related attribute of the flanker would activate the associated responses. In noncorresponding-congruent trials and corresponding-incongruent trials, this would cause a conflict at the response selection stage.

Spatio-temporal brain dynamics in a combined stimulus–stimulus and stimulus–response conflict task

“…We found strong Flanker induced S-S conflict effects on a behavioral level, but the Simon-like spatial S-R conflict only elicited significant interference effects during fast responses and decayed over time with increasing response latencies (De Jong et al, 1994;Hommel, 1997) as indicated by a RT quintile analysis. Thus, our data do not support the most recent report of increasing S-R conflict effects with increasing response latencies (Treccani et al, 2009) but are in line with the temporal overlap model as suggested by Hommel (1997). The temporal overlap model proposes a temporal decay of the task-irrelevant stimulus location code and, therefore, a decay of its modulatory effect on task performance.…”

“…However, the strength of the Simon conflict effect has also shown to depend on the speed of response. The Simon conflict strength is usually increased for fast compared to slow responses (Hommel, 1997;Treccani et al, 2009). The latter fact may partly mask the Simon effect if behavioral data are averaged over fast and slow responses.…”

“…We computed contrast estimates separately for trials with fast responses and slow responses according to the time depended analysis described in the behavioral analysis section. For fast responses we merged the two fastest quintiles of RTs and for slow responses we merged the two slowest quintiles of RTs to examine BOLD signal differences between the two conditions (Hommel, 1997;Treccani et al, 2009). …”

“…This procedure allows for the direct investigation of common and distinct temporal characteristics as well as the temporal interplay between the processing of both types of conflicts. Indirect evidence, however, comes from behavioral studies which either support the notion that S-S conflicts become evident prior to S-R conflicts (Kornblum et al, 1999), that both S-S and S-R conflicts modulate later stages of information processing beyond the level of stimulus encoding (Simon and Berbaum, 1990) or at the response preparation stage (Treccani et al, 2009). According to Hommel's (1997) temporal overlap model the processing of both types of conflicts is separated but with some overlap in time.…”

Dissociation between Awareness and Spatial Coding: Evidence from Unilateral Neglect

“…The joint effect of flanker position and color had been previously investigated with normal participants in a study using the same task as that administered here (Treccani, Cubelli, Della Sala, & Umiltà, 2009). Consistent with the most widely accepted theories of compatibility phenomena, this study showed an interactive effect of targetflanker color congruency and flanker-response spatial correspondence: What mattered most for performance was not whether the response signaled by either flanker attribute was the required response but rather whether the responses signaled by the two flanker attributes corresponded or did not corresponded.…”