The interference effect of direct eye gaze in the Stroop paradigm

Direct eye gaze is a salient social stimulus that may hinder concurrent task performance, even when presented with another prominent distracter, such as the incongruent word in the Stroop paradigm. Previous studies (Chevallier et al., 2013; Conty et al., 2010) reported a stronger Stroop effect when direct gaze (vs. closed eyes)
was shown above the letter strings, though not all studies found this effect. We had two main goals. The first was to replicate the increased Stroop effect under direct eye gaze. The second was to test whether this effect is specific to another person's eyes (ostensive nature explanation) or also occurs for one's own eyes (salience explanation). In two experiments (one with a trial-based and one with a block-based manipulation), participants performed the Stroop task while presented with either their own or another person's direct gaze versus closed eyes. We found no increased Stroop effect under direct eye gaze compared to closed eyes, irrespective of whether one's own eyes or another person's eyes were presented. We conducted a third experiment to directly replicate the original findings by Conty et al. (2010) and Chevallier et al. (2013), including only another person's eyes. Again, no increase in the Stroop effect under direct eye gaze was found. A pooled analysis across the three experiments provided strong evidence for the null hypothesis. Taken together, we could not replicate previous findings of direct eye gaze increasing the Stroop effect. Our findings underline the central importance of replication studies and negative findings in experimental psychology