Influence of Oxytocin on Neurophysiological Responses to Live Faces

Previous research has indicated that direct eye gaze compared to averted gaze, elicits a higher skin conductance response (SCR), and a more pronounced left frontal cortex activity than right frontal cortex activity (resulting in positive asymmetry scores). On a behavioral level, participants tend to look shorter at live faces with a direct gaze as compared to averted gaze (Akechi et al., 2013). Further, subjective evaluations showed that a direct gaze is rated more arousing and less pleasant than an averted gaze (Akechi et al., 2013; Hietanen, Leppänen, Peltola, Linna-aho, \& Ruuhiala, 2008).

Importantly, oxytocin administration increases the number of fixations and to looking time towards the eye region during live social interaction. Further, oxytocin has been shown to influence SCR and heart rate variability. Therefore, it is conceivable that oxytocin will not only influence the gaze duration of the participant, but also the physiological and neurological responses elicited by direct eye gaze.

In this study, the investigators will investigate whether oxytocin modulates the behavioural (eye gaze and subjective ratings), neurological (EEG) and physiological (skin conductance, heart rate and respiration) responses elicited by direct gaze.

Previous research has indicated that direct eye gaze compared to averted gaze, elicits a higher skin conductance response (SCR), and a more pronounced left frontal cortex activity than right frontal cortex activity (resulting in positive asymmetry scores). On a behavioral level, participants tend to look shorter at live faces with a direct gaze as compared to averted gaze (Akechi et al., 2013). Further, subjective evaluations showed that a direct gaze is rated more arousing and less pleasant than an averted gaze (Akechi et al., 2013; Hietanen, Leppänen, Peltola, Linna-aho, \& Ruuhiala, 2008).

Importantly, oxytocin administration increases the number of fixations and to looking time towards the eye region during live social interaction. Further, oxytocin has been shown to influence SCR and heart rate variability. Therefore, it is conceivable that oxytocin will not only influence the gaze duration of the participant, but also the physiological and neurological responses elicited by direct eye gaze.

In this randomized, placebo controlled, double blinded study, the investigators will investigate whether oxytocin modulates the behavioral and neurophysiological responses elicited by direct gaze. In order to do so, the investigators will measure behavioural (eye gaze and subjective feelings), physiological (skin conductance, blood volume pulse, and respiration) and neurological (EEG) responses during presentations of a live person's face with direct gaze and closed eyes, before and after oxytocin or placebo administration.

The investigators hypotheses that oxytocin attenuates the heightened SCR and pronounced EEG asymmetry during direct gaze. Further, they expect that oxytocin increases the number of fixations and duration of those fixations towards the eye region. Exploratory, the investigators will also investigate whether oxytocin administration influences respiration and the subjective reports on experience of live eye contact. Lastly (and also exploratory), they will explore whether certain personality traits (as measured by SAAM (state adult attachment measure) and SRS (social responsiveness scale)) influence the modulatory effect of oxytocin on neurological and behavioural responses.

Note that this study is part of a larger study in which the investigators also register several neurophysiological responses (blood volume pulse, respiration, heart rate, EEG, skin conductance) during rest before and after oxytocin or placebo administration.

Eligibility Criteria:
Inclusion Criteria:

* right-handed
* male
* age between 18 and 35
* Normal or adjusted-to-normal vision (with lenses only)
* Dutch as mother tongue

Exclusion Criteria:

* not right-handed
* female
* age below 18 or above 35
* Need to wear glasses
* Dutch not as mother tongue