On the nature of the Reverse Congruency Effect for gaze stimuli: Exploring the joint attention hypothesis

Recent evidence reported differences in attentional shifting between eye-gaze and arrow stimuli. Specifically, in a spatial Stroop task, arrows induced a standard congruency effect (SCE; faster reaction times for congruent vs. incongruent trials), while eye-gaze stimuli elicited a reversed congruency effect (RCE; faster reaction times for incongruent vs. congruent trials). Our study aimed to explore the origins of the RCE in relation to the ‘joint attention hypothesis’, which postulate that, on incongruent trials, eye-gaze stimuli are ‘looking’ at the same object fixated by the participant (i.e., the fixation point), a condition that did not apply to arrows. In four experiments, participants (Ntot = 240) reported the direction indicated by the target stimulus (eye-gaze or arrow), which appeared to the left or right of a central fixation point. To test the joint attention hypothesis, we varied the fixation point: a meaningful real-life object (typically linked to joint attention) or a symbolic cross. The results showed a SCE for arrows and a RCE for eye-gaze stimuli, regardless of the fixation point type. These findings did not support the joint attention hypothesis. Ongoing research aims to clarify this effect