Different types of semantic interference, same lapses of attention: Evidence from Stroop tasks

This research investigated the possibility that semantic control mechanisms are recruited only when the interfering semantic information does not overlap with task-relevant semantic dimensions. To reach this goal, we investigated two semantic types of Stroop interference—the semantic and the taboo Stroop effects—and used delta-plots to investigate the role of attentional and semantic control in these two interference phenomena. The semantic Stroop effect, where interference stems from the task-relevant color-related information, was absent in faster responses, whereas it steeply increased in the slowest ones. Contrary to our predictions, the same pattern was detected even for the taboo Stroop interference, with no trace of selective suppression of the interfering semantic connotation, despite its dissociation from any task-relevant semantic dimension. Further, there was a significant correlation between the increase of the two effects in the slowest responses, pointing towards a common underlying processing dynamic. We identified such common background with lapses of executive attention in maintaining task goals and schema, which in turn make the participants performance more prone to interference phenomena. Finally, the absence of any interference effects in the fastest responses suggests that an effective filtering of the distracting word stimuli can be implemented in the context of Stroop paradigms.