The purpose of the study is to learn how differences in learning under mildly-stressful circumstances may be changed by taking oxytocin. Oxytocin is a hormone made naturally in the body. The investigators will also examine the impact of any anxiety, depression, and stress related symptoms on learning processes.

Inclusion Criteria:

• Men or women 18 to 65 years of age
• Score in study range on the Neuroticism-Extraversion-Openness-Five Factor Inventory (NEO-FFI)
• No current Axis I Diagnostic and Statistical Manual-IV (DSM) excluded diagnoses as determined by the Structured Clinical Interview DSM (SCID) completed within the past 4 months.
• Must be able and willing to understand study procedures and return to the clinic on two separate consecutive days for the fear-conditioning procedures.
• Subjects must be able to give informed consent and be willing and able to comply with study procedures.

Exclusion Criteria:

• Presence of a current DSM-IV Axis I diagnosis as measured by the SCID.
• A serious medical condition or other condition deemed likely to result in surgery or hospitalization, or which would make participation in the study difficult.
• Patients with a history of trauma resulting in head injury related seizures or with epilepsy (except a prior history of febrile seizures of infancy which are not exclusionary).
• Use of supplemental hormones (birth control, estrogen, testosterone, prednisone, etc) or narcotics.
• Pregnant or lactating women.
• Women of childbearing potential not using medically accepted forms of contraception.
• Current use of the excluded psychiatric medications.
• Known hypersensitivity to oxytocin
• Known hyponatremia.

Although 60 participants were enrolled, only 30 participants had usable physiological data from recording electrodes, and therefore, the only data analyzed were from these 30 participants (16 placebo and 14 oxytocin).