Intranasal oxytocin enhances the perception of ambiguous averted gaze in women but not in men.

BACKGROUND: Perceiving accurately that others are looking away from us (averted gaze) is as important, for social interactions, as perceiving that others are looking at us (direct gaze). However, previous studies have revealed that when the deflection angle of averted gaze is small, individuals tend to falsely perceive it as direct gaze. Oxytocin (OXT) has been shown to increase orientation to the eye region. Therefore, a critical question is whether and how OXT would facilitate the perception of ambiguous averted gaze. OBJECTIVES: The present study aimed to measure the effects of OXT on the performance of males and females in distinguishing ambiguous averted gaze from direct gaze of different emotional faces. METHODS: In a double-blind placebo-controlled crossover experiment, 48 participants were presented successively two emotional faces with direct gaze (defined as 0, indicating the center of the eye) or averted gaze (defined as ±4, indicating the corner of the eye; +4 means that the iris moves 4 steps to the right; and -4 means that the iris moves 4 steps to the left) following intranasal oxytocin or placebo treatment and asked to make judgments on whether or not the two faces were the same in terms of identity. The interference effect of gaze direction was calculated by subtracting the mean accuracy and reaction time in the congruent gaze condition from those in the incongruent gaze condition. The logic of the measurement was if intranasal OXT would facilitate the detection of ambiguous averted gaze, we would observe a larger interference effect in the gaze incongruent condition compared with the gaze congruent condition, leading to longer RT or/and lower accuracy for identification judgment in the gaze incongruent condition. RESULTS: While there were no OXT effects in accuracy, we found a significant interaction between treatment, sex, and gaze congruency in reaction times. That is, following OXT as compared to placebo, women displayed stronger interference of gaze direction, whereas in men no significant difference was observed. Besides, this interaction did not vary across different emotional expressions. CONCLUSIONS: Our findings provide the first evidence for sex-dependent effects of OXT on the perception of ambiguous averted gaze. Given potential therapeutic applications of OXT to patients with developmental and psychiatric disorders, who are characterized as atypical in encoding gaze features, the findings suggest that rather different treatment outcomes could be anticipated in males and females.

Opposing sex-dependent effects of oxytocin on the perception of gaze direction.

BACKGROUND: Gaze direction is an important cue of the eye region. Previous studies have revealed that oxytocin (OXT) increases orienting to the eye region of face. However, little has been known about the effect of OXT in men and women on the perception of gaze direction particularly when associated with different emotions. OBJECTIVES: We investigated how oxytocin would affect gaze direction judgments for threatening, angry, and neutral facial expressions and whether this effect would be modulated by observers' sex. METHODS: We used the cone of direct gaze (CoDG) task. Participants were required to judge the gaze direction of face between directed and averted gaze. RESULTS: Results showed opposing sex-dependent effects of OXT such that OXT, as compared with placebo, tended to decrease the CoDG in men but increase it in women. The CoDG was marginally wider in men than in women in the placebo condition, and however, this difference was abolished following OXT treatment. We also found that the perception of gaze direction varied as a function of emotional expression such that the CoDG for angry and neutral faces was wider than that for fearful faces and the CoDG for angry faces was marginally wider than that for neutral ones. However, there was no significant interaction between treatment and facial expression. CONCLUSIONS: Our findings provide the first evidence for sex-dependent effects of OXT on gaze direction perception, suggesting that OXT attenuates the self-referential judgment of gaze directions of others in men and enhances it in women despite differentiated emotions of faces.