Psychosis Participants:  Inclusion Criteria:  Meet diagnostic criteria for a psychotic disorder (schizophrenia, schizoaffective disorder, schizophreniform disorder, major depressive disorder with psychotic features, bipolar disorder with psychotic features, psychosis disorder not otherwise specified, or unspecified schizophrenia spectrum disorder), as defined by the MINI (Mini-International Neuropsychiatric Interview) Are age 18-64 (inclusive) Fluent in written and spoken English Have an outpatient status of at least 1 month prior to participation Has been on a stable dose of psychiatric medication for at least one month prior to participation (titration to a lower dose of psychotropic medications under supervision of a psychiatrist can be allowed at the discretion of the investigators)  Exclusion Criteria:  History of seizures or epilepsy Metallic cranial plates, screws, or implanted devices History of craniotomy History of stroke History of eczema on scalp Pre-existing sores or lesions at sites of tACS electrode placement Non-removable facial piercings Current or possibility of current pregnancy Active suicidal ideation at screening or baseline assessments, or previous intent to act on suicidal ideation with a specific plan, preparatory acts, or an actual suicide attempt within the last 3 months, as indicated by the MINI and/or C-SSRS (All participants will complete the suicide module of the MINI. If participants express any suicidal ideation on the MINI, staff will complete the C-SSRS [Columbia-Suicide Severity Rating Scale].) WTAR (Wechsler Test of Adult Reading) standardized score below 70 Any reason our tCS (transcranial stimulation) or EEG caps cannot be placed on their head  Control Participants:  Inclusion Criteria:  Are age 18-64 (inclusive) Fluent in written and spoken English  Exclusion Criteria:  Meet diagnostic criteria for a psychotic disorder (schizophrenia, schizoaffective disorder, schizophreniform disorder, major depressive disorder with psychotic features, bipolar disorder with psychotic features, psychosis disorder not otherwise specified, or unspecified schizophrenia spectrum disorder), as defined by the MINI Self-reports having a first-degree relative with a psychotic disorder History of seizures or epilepsy Metallic cranial plates, screws, or implanted devices History of craniotomy History of stroke History of eczema on scalp Pre-existing sores or lesions at sites of tACS electrode placement Non-removable facial piercings Current or possibility of current pregnancy Active suicidal ideation at screening or baseline assessments, or previous intent to act on suicidal ideation with a specific plan, preparatory acts, or an actual suicide attempt within the last 3 months, as indicated by the MINI and/or C-SSRS (All participants will complete the suicide module of the MINI. If participants express any suicidal ideation on the MINI, staff will complete the C-SSRS.) WTAR standardized score below 70 Any reason our tCS or EEG caps cannot be placed on their head