Sequential modulation of the Cross-modal Congruency effect: the role of target and distractor sensory modality

Sequential analyses of conflict tasks such as the flanker task have shown reduced congruency effects following incongruent trials (i.e. he Gratton effect ; Gratton et al., 1992). According to the Conflict Monitoring Hypothesis (Botvinick et al., 2001), top-down cognitive control is increased following response conflict on incongruent trials, improving performance on a subsequent incongruent trial. Recent studies have shown the presence of the Gratton effect also in cross-modal congruency tasks (CCT) in which a target in one sensory modality is simultaneously presented with a distractor in a different sensory modality. This demonstrates that the combination of crossmodal stimuli presented on the previous trial impacts performance on a subsequent trial. However, it is not known whether the Gratton effect measured in a CCT is shaped by the specific combination of sensory modalities of the different target-distractor pairings. To address this question we asked participants to complete four CCTs in which a visual target was presented simultaneously with either a tactile or an auditory distractor or in which a visual distractor was accompanied by a tactile or an auditory target. Stronger congruency effects were present when vision was task-irrelevant than when it was task-relevant. Importantly, a reduction of the congruency effect following an incongruent trial (i.e. Gratton effect) was observed with visual distractors, but not with visual targets. Thus, visual distractors strongly activated the spatially corresponding response resulting in large congruency effects and leading to an increased top-down control following an incongruent trial. By contrast, tactile and auditory distractors only weakly activated the spatially corresponding response, reducing the need for increased cognitive control after incongruent trials. Together these findings reveal that the cognitive control processes engaged during CCT are strongly dependent on the specific combination of modalities of target and distractor.