Inclusion Criteria:
* Participant is willing and able to give informed consent for participation in the research
* Sufficiently fluent English to understand and complete the task
Exclusion Criteria:
* Participants with ferromagnetic objects in their bodies (e.g. metal implants, vessel clips, shrapnel injuries) or with implanted devices which may be damaged by the magnet (e.g. heart pacemakers)
* Any other MRI contraindication following MRI safety screening
* History or current significant psychiatric illness (like major depressive disorder)
* Current or past diagnosis of any significant personality disorder (e.g. borderline personality disorder) according to self-report
* Diagnosis of attention deficit hyperactive disorder or autistic spectrum disorder that impairs daily functioning, requires pharmacotherapy or in the opinion of the study medic would affect the scientific integrity of the study
* Currently or within last 3 months taking psychoactive medications (requires further discussion with researcher)
* Current or within the last 3 months use of medication that might interact with the effects of citalopram or affect the scientific integrity of the study
* Known contraindication to citalopram including: past allergic reaction to citalopram or any other medicines, diagnosis of a cardiovascular condition, glaucoma, type 1 or type 2 diabetes, diagnosis of epilepsy, previous diagnosis of angle-closure glaucoma, or current use of any other medication whose use interacts with citalopram (according to British National Formulary (BNF) guidance) e.g. associated with prolonged QT-interval
* Any other current or past medical conditions which in the opinion of the study medic may interfere with the safety of the participant or the scientific integrity of the study including epilepsy/seizures, brain injury, hepatic or renal disease, diabetes, severe gastro-intestinal problems, Central Nervous System (CNS) tumours, neurological conditions
* Clinically significant abnormal values for urine drug screen, pulse, and blood pressure measurement (in accordance with Best Practice Guidance 13: 'Non-invasive measurement of blood pressure'). A participant with a clinical abnormality or parameters outside the reference range for the population being studied may be included only if the Investigator considers that the finding is unlikely to introduce additional risk factors and will not interfere with the study procedures
* Current alcohol or substance misuse disorder
* Body Mass Index under 18 and over 30
* Pregnant or planning a pregnancy, or breast feeding
* Previously taken part in a study that used similar computer tasks (MRI faces task, emotional test battery) as those in the present study
* Participation in a study that involves the use of a psychoactive medication or brain stimulation within the last three months
* Use of recreational drugs (e.g. cannabis, cocaine, amphetamines) within last three months
* Smoking \> 5 cigarettes per day, or vape a comparable amount (\> 0.5ml / a quarter of a 2ml vape);
* Typically drinks \> 6 caffeinated drinks per day (e.g. tea, coffee, coca cola, Red Bull)
* Participant is unlikely to comply with the clinical study protocol or is unsuitable for any other reason, in the opinion of the Investigator
