Analysis of non-social stimuli with similar asymmetrical contrast features of eye-gaze stimuli

Eye-gaze plays a crucial role in social interactions and may activate different attentional orienting mechanisms compared to non-social cues. By using a spatial interference paradigm, it has been observed that arrows result in faster reaction times in congruent than incongruent trials, facilitating a standard congruency effect (SCE). In contrast, eye-gaze results in faster reaction times in incongruent than congruent trials, producing a reversed congruency effect (RCE)—a pattern potentially driven by the social significance of gaze processing. This reversion might be facilitated by the social significance of gaze processing. Additionally, from a distributional perspective using the using the conditional accuracy function (CAF), social targets elicited higher error rates for congruent than incongruent trials with social stimuli were observed within the fastest responses. Both congruent and incongruent trials showed reduced accuracy in the first bins. These patterns differ from those observed with non-social stimuli, which typically exhibit higher error rates for incongruent trials in the fastest responses, with such differences diminishing across the distribution. Based on these observations, we aimed to examine the hypothesis that the dissociations observed with reaction times and the CAF tool with gaze are due to the incongruent location of the salient sclera (opposite to the less salient pupils of the eyes). To test this, we adapted non-social stimuli to have a contrast pattern similar to eye-gaze. We used two types of arrow targets: Eyes-like (darker, less salient on the target arrowhead) and Anti-Eyes-like (darker, less salient on the arrow tail) arrows (Experiment 1) and the same two target types embedded in a mosaic background (Experiment 2). Our results revealed no reversion for both target types, showing the SCE independently of the contrasting features. Additionally, no dissociation was observed with the CAF; both Eyes-like and Anti- Eyes-like arrows showed similar patterns, aligning with traditional non-social stimuli in distributional analysis studies. This suggests that the reversion is not elicited by the contrasting perceptual features of the stimuli, and the social nature of the stimuli gaze processing might underlie the reversions, as suggested in previous studies. observed with RTs and accuracy.