Electrophysiological correlates of the reverse Stroop effect: Results from a simulated handgun task.

The color-word reverse Stroop (RS) effect still represents an interesting puzzle for cognitive researchers as an interference between incongruent ink colors and the meaning of the words is not always found. Here, we examined whether an unfamiliar and complex visuomotor task would produce a RS effect. Forty inexperienced shooters carried out a simulated shooting task. To test if the RS effect is related to the stimuli processing or to a late processing of the color (early and late time-windows), electroencephalographic global field power (GFP) variations were recorded with a high-impedance system (32 channels configuration in a standard monopolar montage, referenced to FCz and grounded to FPz). The color-word RS effect was reflected in the performance of 32 participants, suggesting that the strength of the association between the target and the specific response requested might be central to the RS interference. This behavioral result was paralleled by GFP modulations in 20 participants. A significant increase of the GFP for the congruent trials (e.g., the word "red" written in red ink) was recorded after stimulus presentation (conflict detection), followed by an increase for the incongruent trials (e.g., the word "red" written in green ink) just before the shooting (conflict resolution). Despite the limitations of the study, such as the inclusion of a low number of channels in the GFP analyses, the results suggest that the RS interference is easily elicited in tasks requiring an unfamiliar response, which supports the strength of association hypothesis. Moreover, as implied by the GFP modulations, the interference might occur early in time, but also in a later stage, closer to the response.