Oxytocin (OT) is a neuropeptide that acts as a neurotransmitter and neuromodulator in the brain. Previous studies have shown that intranasal administration of OT improves social cognition and behavior (e.g. emotion recognition). In the current study, we want to gain more insight into the underlying mechanisms by which OT influences emotion recognition. More specifically, we will investigate whether intranasal administration of OT enhances the salience of social (compared to non-social) information and whether it increases the neural sensitivity for subtle socio-emotional cues, by recording scalp electroencephalography (EEG) during Fast Periodic Visual Stimulation (FPVS).

The present study is a double-blind, randomized, placebo-controlled, crossover clinical trial, in which (approximately 30) neurotypical male adults (18 to 30 years old) will participate. All participants will perform two sessions (OT and placebo), separated by two weeks. For the first session, the participants are randomly assigned to the placebo or the OT condition. Syntocinon nasal spray will be used for intranasal administration.

In each session, we will measure the neural salience/sensitivity for socio-emotional information, by recording EEG during FPVS. Participants simply have to press a button when the fixation cross turns red, while watching rapidly alternating visual stimuli. Starting 20 minutes after substance intake, four FPVS paradigms are administered in randomized order:

1. A frequency-tagging FPVS paradigm, to measure the salience of social versus non-social stimuli.
2. The oddball face detection paradigm, to assess the neural sensitivity to faces embedded in a series of objects.
3. The oddball identity discrimination task, to examine the ability to discriminate between faces with a different identity.
4. The oddball expression generalization task, to investigate the sensitivity for facial emotional expressions embedded within neutral faces with varying identities.

After two FPVS paradigms, a four minutes resting state EEG measure will be performed. At the end of the session, emotion recognition will be measures with the Palermo matching task (65 items).

The primary aim is to investigate whether the performance on each of these paradigms/tasks differs between the OT and the placebo condition. Furthermore, we want to explore whether the effect of OT is influenced by the participant's attachment style, social responsiveness, social phobia, or mood, which will be assessed via self-reported questionnaires.

Inclusion Criteria:

• age between 18 and 30 years
• male
• right-handed
• typically developing
• Normal or adjusted-to-normal vision (with glasses or lenses)

Exclusion Criteria:

• psychiatric disorder
• neurological disorder (e.g. epilepsy, migraine)
• color blindness
• psychoactive medication