Oxytocin increases eye-gaze towards novel social and non-social stimuli

Abstract

Research on oxytocin (OT) has revealed a substantial involvement of this neuropeptide in social cognition processes and attachment behavior. The rationale of the present project was to decipher the differential role of OT in basic social cognition processes towards non-erotic attachment stimuli vs. reproduction-related stimuli in human subjects. In a randomized double-blind repeated-measures cross-over design, N = 82 participants were investigated twice and received either intranasal OT or placebo at the first assessment followed by placebo or OT at second assessment. Participants were presented with standardized pictures of parent-child dyads, romantic couples engaging in non-erotic or explicit sexual activities, and non-social pictures while we assessed pupil dilation and eye focus on specific pre-defined areas of interest. Multilevel analyses suggest that during the initial presentation, OT increased pupil dilation towards all categories of stimuli and led the eye focus towards the eyes and body regions, followed by a strong decrease in pupil dilation and fixations at the second session. These carry-over effects indicate that hormonal treatment at an initial contact to social stimuli can determine how these stimuli are processed later. These results might have implications for OT as a treatment in interventions with repeated exposure to social material.

Keywords: Eye-tracking; intranasal oxytocin; parent-child attachment; sexual stimuli; social bonding; social perception.

Figure 1. a) Experimental Procedure and (b) Randomized Cross-Over Design

Participants performed two identically structured sessions approximately 14 days apart. They received either OT in the 1^st session and PL in the 2^nd session or vice versa in a double-blind manner before being presented blocks of bonding, neutral and sexual pictures. Abbreviations: OT, Oxytocin, PL, Placebo

Figure 2. Example Stimuli and AOIs $$PARABREAKHERE$$a) + b) Category Attachment, c) Category Erotic, d) Category Mother-Child, d) Category Father-Child, f) Category Sex

(GF = Woman’s Face, AF = Woman’s Eyes, KF = Woman’s Body, GM = Man’s Face, AM = Man’s Eyes, KM = Man’s Body, GK = Child’s Face, AK = Child’s Eyes)

Figure 3. Descriptive Values Pupil Dilation

OT application at the 1^st experimental session lead to enhanced pupil dilation in the first session; OT, Oxytocin, PL, Placebo; Error Bars indicate Standard Error of the Mean (SEM)

Figure 4. Predicted Values Pupil Dilation

Multilevel analysis resulted in significant 2-way-interaction of treatment and time of assessment; neutral served as reference category; OT, Oxytocin, PL, Placebo; Error Bars indicate Standard Error of the Mean (SEM)

Figure 5. Descriptive Values Fixation Count

OT application at the 1^st experimental session lead to enhanced fixation of (a) eye regions and (b) body regions OT, Oxytocin, PL, Placebo; Error Bars indicate Standard Error of the Mean (SEM)

Figure 6. Predicted Values Fixation Count

Multilevel analysis resulted in significant 3-way-interaction of treatment, time of assessment and AOI for the AOIs adult’s eyes, child’s eyes, adult’s body; background served as reference category; OT, Oxytocin, PL, Placebo; Error Bars indicate Standard Error of the Mean (SEM)