The Effect of LSD on Neural Synchrony, Prosocial Behavior, and Relationship Quality

Inclusion Criteria: * Written Informed Consent * Understanding the procedures and the risks associated with the study. * Age between 18 and 35 years old. * Being in a steady relationship for at least 6 months. * Proficient knowledge of the English language * Previous experience with at least one psychedelic drug (psilocybin, LSD, mescaline, Ayahuasca, DMT, 5-MeO-DMT), but not within the past 3 months * Absence of any major medical condition as determined by medical examination and laboratory analysis * Absence of any major psychological condition as determined by medical examination * Free from psychotropic medication * Participants must be willing to refrain from taking illicit psychoactive substances during the study. * Participants must be willing to drink only alcohol-free liquids and no coffee, black or green tea, or energy drink after midnight of the evening before the study session, as well as during the study day. * Participants must be willing not to drive a traffic vehicle or to operate machines within 24 h after substance administration. * Normal weight, body mass index (weight/height2) between 18 and 28 kg/m2 Exclusion Criteria: * History of drug addiction (determined by the medical questionnaire, drug questionnaire and medical examination) * Previous experience of serious side effects to psychedelic drugs (anxiety or panic attacks) * Pregnancy or lactation * Hypertension (diastolic \> 90 mmHg; systolic \> 140 mmHg) * Current or history of psychiatric disorder …