The Loci of Stroop Interference and Facilitation Effects With Manual and Vocal Responses.

Maria Augustinova,Benjamin A Parris,Ludovic Ferrand

doi:10.3389/fpsyg.2019.01786

Abstract

Several accounts of the Stroop task assume that the Stroop interference effect has several distinct loci (as opposed to a single response locus). The present study was designed to explore whether this is the case with both manual and vocal responses. To this end, we used an extended form of the Stroop paradigm (Augustinova et al., 2018b) that successfully distinguishes between the contribution of the task vs. semantic vs. response conflict to overall Stroop interference. In line with past findings, the results of Experiment 1 yielded an important response modality effect: the magnitude of Stroop interference was substantially larger when vocal responses were used (as opposed to key presses). Moreover, the present findings show that the response modality effect is specifically due to the fact that Stroop interference observed with vocal responses results from the significant contribution of task, semantic, and response conflicts, whereas only semantic and response conflicts clearly significantly contribute to Stroop interference observed with manual responses (no significant task conflict was observed). This exact pattern was replicated in Experiment 2. Also, and importantly, Experiment 2 also investigated whether and how the response modality effect affects Stroop facilitation. The results showed that the magnitude of Stroop facilitation was also larger when vocal as opposed to manual responses were used. This was due to the fact that semantic and response facilitation contributed to the overall Stroop facilitation observed with vocal responses, but surprisingly, only semantic facilitation contributed with manual responses (no response facilitation was observed). We discuss these results in terms of quantitative rather than qualitative differences in processing between vocal and manual Stroop tasks, within the framework of an integrative multistage account of Stroop interference (Augustinova et al., 2018b).

Highlights

The typical results in the well-known Stroop task (Stroop, 1935) are at least twofold
This latter result implies that, in the Stroop task administered with manual responses, the contribution of task conflict to the overall Stroop interference failed to reach significance, whereas the contribution of both semantic (i.e., SKYgreen – XXXgreen) and response conflicts (i.e., BLUEgreen – SKYgreen) was significantly independently of the response output that was required
The results of Experiments 1 and 2 yielded an important response modality effect – the direction of which was consistent with past findings (e.g., White, 1969; Redding and Gerjets, 1977; Neill, 1977; McClain, 1983; Sharma and McKenna, 1998; Kinoshita et al, 2018; Fennell and Ratcliff, 2019; Zahedi et al, 2019; Parris et al, in press)

Summary

INTRODUCTION

The typical results in the well-known Stroop task (Stroop, 1935) are at least twofold. Given that color-associated words do not activate (pre-)motor responses linked to the associated color (e.g., press a blue button on seeing SKY; see Schmidt and Cheesman, 2005 for a direct demonstration), the aforementioned contribution of semantic conflict to overall Stroop interference is not confounded with that of response conflict – generated by standard color-incongruent words only (e.g., BLUEgreen, but see Hasshim and Parris, 2014, 2015 for a discussion of this study). The positive difference in mean response latencies between color-associated incongruent and color-neutral trials (e.g., SKYgreen – DOGgreen) was used as a proxy for assessing the specific contribution of semantic conflict to overall Stroop interference. Given the important discrepancies between findings regarding whether and the extent to which task and semantic conflict occur, respectively, with manual and vocal responses, we only a priori predicted that in both studies, the magnitude of Stroop interference will be larger with vocal as compared to manual responses and that this difference should result at least in part from a difference in response conflict

Method

Results and Discussion

GENERAL DISCUSSION

ETHICS STATEMENT