Social psychology has long established that the mere presence of others influences the investigator's individual behavior and performance. "Social facilitation" refers to any improvement or deterioration of performance due to the presence of others. For more than a century, social psychology has acquired a solid knowledge of the principles governing this fundamental form of social influence.

But the underlying mechanism of social facilitation remains debated, as behavior alone cannot identify it with certainty. This major unresolved problem makes it particularly difficult to translate laboratory results on social facilitation into real applications in areas such as school or work, where others are ubiquitous. The purpose of this study will therefore be to identify the mediator of social facilitation.

Inclusion Criteria:

• Male or female
• Aged 18 to 35 years old
• Signed written informed consent
• Insurance coverage

Exclusion Criteria:

• Neurological or psychiatric or ophthalmological disorder

• Non-stabilized medical condition

• Ongoing treatment with drugs that affect the central nervous system

  • Uncorrected visual inadequacy
  • No fluency in French reading
  • Pregnant and / or breastfeeding woman, this exclusion criterion will be sought by questioning the subject
  • Subject commonly in care in a health or social facility for purposes other than that of research
  • Subject under guardianship
  • Subject deprived of liberty by a judicial or administrative decision
  • Incompatibility with the Magnetic Resonance Imaging (MRI) examination determined by answering the following questions:

• Carrier of a neurological stimulator, cardiac (battery) or defibrillator

• Carrier of a cardiac prosthesis (valve, stent ...) or vascular

• Holder of intracranial clips or clamps (staples)

• Carrier of a cerebrospinal fluid bypass

• Presence of metal chips in the eyes

• Metal prosthesis carrier (teeth, knees)

• Pump carrier or infusion system

• Presence of metal tattoo near the head

• Presence of permanent makeup

• Claustrophobia or respiratory disorders