Subjective Experience Following Psilocybin

Inclusion Criteria:

* Individuals of all sexes, gender identities, and ethnicities
* Ages 18 to 65 years of age at the time of screening
* Ability to read/write in English
* Agree not to consume psychoactive drugs 24 hours before dosing sessions or consume psychedelics during duration of study participation
* At least one self-reported positive experience prior to study participation with a psychoactive substance, specifically those known for altering perception or inducing hallucinatory effects (cannabis or psychedelics, including psilocybin, LSD, DMT, mescaline) or experience with non-pharmacological altered states of consciousness (meditation, breathwork)

Exclusion Criteria:

* Any notable abnormality on electrocardiogram or routine medical blood or urinalysis laboratory tests: I.e., unstable cardiac, renal, or liver disease, uncontrolled hypertension or diabetes, or other medical condition, as determined by the study staff, that could compromise participant safety
* Serious electrocardiogram abnormality, i.e., evidence of ischemia, myocardial infarction, QTc (Fridericia formula) prolongation (QTc \> 0.45 for men, QTc \> 0.47 for women).
* Abnormal liver enzymes (AST, ALT, GGT ≥4 times upper normal limit)
* Pre-existing low white blood cell count or a history of drug-induced leukopenia/neutropenia
* Insulin-dependent diabetes; if taking oral hypoglycemic agent, then no history of hypoglycemia
* History of epilepsy or seizures, neuroleptic malignant syndrome or tardive dyskinesia
* Hypertension (\>140mmHg systolic or 90mmHg) or Tachycardia (HR \>100bpm) as measures by best result of maximum of three vital sign recordings in a supine position after a 5 min resting period. Participants with a blood pressure not higher than 165/95 or a heart rate of not higher than 110bpm can be conditionally enrolled but dosing will only happen if the vitals at the dosing sessions are in the limits outlined above for inclusion.
* Current psychiatric diagnoses, such as major depressive disorder, generalized anxiety disorder, panic disorder, social anxiety disorder, obsessive compulsive disorder, moderate to severe substance use disorders, eating disorders, personality disorders, post-traumatic stress disorder
* Lifetime or current psychiatric diagnoses of psychosis, schizophrenia, bipolar disorder
* Family history: a first- or second degree relative with a history of schizophrenia or other psychotic disorders, bipolar I or II
* Medication: Any medication with the potential to interact with the investigational medicinal products, especially those with serotonergic mechanisms of actions like SSRIs, SNRIs or MAO-Inhibitors as well as other antipsychotics. Medication with potential drug-drug interactions (especially uridine 5'-diphospho-glucuronosyltransferase (UGT) and ALDH inhibitors and alcohol dehydrogenase (ADH) inhibitors for psilocybin and CYP2D6- and to a lesser extend CYP3A4 modulators for risperidone) are prohibited for at least 5 half-lives of the active moiety before the dosing.
* Serotonergic psychedelic use in the past 3 months (e.g. psilocybin, LSD, DMT, mescaline)
* Serious adverse events following previous psychedelic use
* Currently pregnancy or nursing, trying to become pregnant, or unwilling to use acceptable method of contraception during the study
* Acceptable methods of contraception include oral contraceptives, barrier with spermicide, IUD, medroxyprogesterone acetate (Depo Provera), contraceptive patch, vaginal contraceptive ring, or being post-menopausal or deemed medically unable to become pregnant (i.e., due to hysterectomy)
* Current or recent (within 12 weeks) participation in a clinical trial involving medication administration
* Any sensitivity or adverse reaction to previous use of a hallucinogen or risperidone
* Cognitive impairment (Folsetin Mini Mental State Exam score \< 24)
* A disorder that may interfere with drug absorption, distribution, metabolism, or excretion (including gastrointestinal surgery).
* Suffered a traumatic brain injury with one of the following symptoms
* Loss of consciousness \>30min
* Alteration of consciousness/mental state \>24h
* Post-traumatic amnesia \>1 day
* Glasgow Coma Scale (best available score in first 24 hours) \<13
* The participant experienced a significant life event (such as pending loss of housing, family status change, loss of a close friend or relative) that could affect stability in the past 30 days.
* Any other circumstances that, in the opinion of the investigators, compromises participant safety