Delusions: A false belief regarding the self or persons or objects outside the self that persists despite the facts, and is not considered tenable by one's associates.Schizophrenia, Paranoid: A chronic form of schizophrenia characterized primarily by the presence of persecutory or grandiose delusions, often associated with hallucination.Hallucinations: Subjectively experienced sensations in the absence of an appropriate stimulus, but which are regarded by the individual as real. They may be of organic origin or associated with MENTAL DISORDERS.Capgras Syndrome: A psychotic disorder characterized by the patient's belief that acquaintances or closely related persons have been replaced by doubles or imposters.Paranoid Disorders: Chronic mental disorders in which there has been an insidious development of a permanent and unshakeable delusional system (persecutory delusions or delusions of jealousy), accompanied by preservation of clear and orderly thinking. Emotional responses and behavior are consistent with the delusional state.Schizophrenic Psychology: Study of mental processes and behavior of schizophrenics.Psychotic Disorders: Disorders in which there is a loss of ego boundaries or a gross impairment in reality testing with delusions or prominent hallucinations. (From DSM-IV, 1994)Reality Testing: The individual's objective evaluation of the external world and the ability to differentiate adequately between it and the internal world; considered to be a primary ego function.Fantasy: An imagined sequence of events or mental images, e.g., daydreams.Schizophrenia: A severe emotional disorder of psychotic depth characteristically marked by a retreat from reality with delusion formation, HALLUCINATIONS, emotional disharmony, and regressive behavior.Psychoses, Substance-Induced: Psychotic organic mental disorders resulting from the toxic effect of drugs and chemicals or other harmful substance.Delirium, Dementia, Amnestic, Cognitive Disorders: Cognitive disorders including delirium, dementia, and other cognitive disorders. These may be the result of substance use, trauma, or other causes.Psychiatric Status Rating Scales: Standardized procedures utilizing rating scales or interview schedules carried out by health personnel for evaluating the degree of mental illness.Ego: The conscious portion of the personality structure which serves to mediate between the demands of the primitive instinctual drives, (the id), of internalized parental and social prohibitions or the conscience, (the superego), and of reality.Behavioral Symptoms: Observable manifestations of impaired psychological functioning.Superstitions: A belief or practice which lacks adequate basis for proof; an embodiment of fear of the unknown, magic, and ignorance.Paranoid Personality Disorder: A personality disorder characterized by the avoidance of accepting deserved blame and an unwarranted view of others as malevolent. The latter is expressed as suspiciousness, hypersensitivity, and mistrust.Defense Mechanisms: Unconscious process used by an individual or a group of individuals in order to cope with impulses, feelings or ideas which are not acceptable at their conscious level; various types include reaction formation, projection and self reversal.Antipsychotic Agents: Agents that control agitated psychotic behavior, alleviate acute psychotic states, reduce psychotic symptoms, and exert a quieting effect. They are used in SCHIZOPHRENIA; senile dementia; transient psychosis following surgery; or MYOCARDIAL INFARCTION; etc. These drugs are often referred to as neuroleptics alluding to the tendency to produce neurological side effects, but not all antipsychotics are likely to produce such effects. Many of these drugs may also be effective against nausea, emesis, and pruritus.Personal Construct Theory: A psychological theory based on dimensions or categories used by a given person in describing or explaining the personality and behavior of others or of himself. The basic idea is that different people will use consistently different categories. The theory was formulated in the fifties by George Kelly. Two tests devised by him are the role construct repertory test and the repertory grid test. (From Stuart Sutherland, The International Dictionary of Psychology, 1989)Neuropsychological Tests: Tests designed to assess neurological function associated with certain behaviors. They are used in diagnosing brain dysfunction or damage and central nervous system disorders or injury.Thinking: Mental activity, not predominantly perceptual, by which one apprehends some aspect of an object or situation based on past learning and experience.Schizotypal Personality Disorder: A personality disorder in which there are oddities of thought (magical thinking, paranoid ideation, suspiciousness), perception (illusions, depersonalization), speech (digressive, vague, overelaborate), and behavior (inappropriate affect in social interactions, frequently social isolation) that are not severe enough to characterize schizophrenia.Affective Disorders, Psychotic: Disorders in which the essential feature is a severe disturbance in mood (depression, anxiety, elation, and excitement) accompanied by psychotic symptoms such as delusions, hallucinations, gross impairment in reality testing, etc.Religion: A set of beliefs concerning the nature, cause, and purpose of the universe, especially when considered as the creation of a superhuman agency. It usually involves devotional and ritual observances and often a moral code for the conduct of human affairs. (Random House Collegiate Dictionary, rev. ed.)