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magical thinking: The conviction of the individual that his or her thoughts, words, and actions may in some manner cause or prevent outcomes in a way that defies the normal laws of cause and effect.


magnetic resonance imaging (MRI): A technique for measuring the structure (or, in the case of functional magnetic resonance imaging, the activity) of the living brain. The person is placed inside a large circular magnet that causes hydrogen atoms to move; the return of the atoms to their original positions when the current to the magnet is turned off is translated by a computer into pictures of brain tissue.


mainstreaming (immersion): A policy of placing children with disabilities in regular classrooms; although special classes are provided as needed, the children share as much as possible in the opportunities and ambience afforded youngsters without disabilities.


maintenance dose: An amount of a drug designed to enable a patient to continue to benefit from a therapeutically effective regimen of medication. It is often less than the dose required to initiate the positive change.


major (unipolar) depression: A disorder of individuals who have experienced episodes of depression but not of mania.


male erectile disorder: A recurrent and persistent inability to attain or maintain an erection until completion of sexual activity.


male orgasmic disorder: See inhibited male orgasm.


malingering: Faking a physical or psychological incapacity in order to avoid a responsibility or gain an end; the goal is readily recognized from the individual’s circumstances. To be distinguished from conversion disorder, in which the incapacity is assumed to be beyond voluntary control.


malleus maleficarum ("the witches’ hammer"): A manual written by two Dominican monks in the fifteenth century to provide rules for identifying and trying witches.


mammillary body: Either of two small rounded structures located in the hypothalamus and consisting of nuclei.


mania: An emotional state of intense but unfounded elation evidenced in talkativeness, flight of ideas, distractibility, grandiose plans, and spurts of purposeless activity.


manic-depressive illness, manic-depressive psychosis: Originally described by Kraepelin, a mood disorder characterized by alternating euphoria and profound sadness or by one of these moods. Called bipolar disorder in DSM-IV.


manifest content: The immediately apparent, conscious content of dreams. Compare with latent content.


marathon group: A group therapy session run continuously for a day or even longer, typically for sensitivity training, the assumption being that defences can be worn down by the physical and psychological fatigue generated through intensive and continuous group interaction.


marijuana: A drug derived from the dried and ground leaves and stems of the female hemp plant, Cannabis sativa.


marital therapy: See couples therapy.


masked depression: A depression that is expressed in atypical ways not usually associated with the symptoms of depression, such as misbehaving at school.


masochism: See sexual masochism.


mathematics disorder: Difficulties dealing with arithmetic symbols and operations; one of the learning disorders.


mediational theory of learning: In psychology, the general view that certain stimuli do not directly initiate an overt response but activate an intervening process, which in turn initiates the response. It explains thinking, drives, emotions, and beliefs in terms of stimulus and response.


mediator: In psychology, an inferred state intervening between the observable stimulus and response, activated by the stimulus and in turn initiating the response; in more general terms, a thought, drive, emotion, or belief. Also called a construct.


medical (disease) model: As applied in abnormal psychology, a set of assumptions that conceptualizes abnormal behaviour as similar to physical diseases.


medulla oblongata: An area in the brain stem through which nerve fibre tracts ascend to or descend from higher brain centres.


megalomania: A paranoid delusion of grandeur in which an individual believes that he or she is an important person or is carrying out great plans.


melancholia: A vernacular diagnosis of several millennia’s standing for profound sadness and depression. In major depression with melancholia the individual is unable to feel better even momentarily when something good happens, regularly feels worse in the morning and awakens early, and suffers a deepening of other symptoms of depression.


meninges: The three layers of nonneural tissue that envelop the brain and spinal cord. They are the dura mater, the arachnoid, and the pia mater.


meningitis: An inflammation of the meninges through infection, usually by a bacterium, or through irritation. Meningococcal, the epidemic form of the disease, takes the lives of 10 percent of those who contract it and causes cerebral palsy, hearing loss, speech defects, and other forms of permanent brain damage in one of four people who recover.


mental age: The numerical index of an individual’s cognitive development determined by standardized intelligence tests.


mental disorder: A behavioural or psychological syndrome associated with current distress and/or disability.


mental health status: An individual's level of distress and cognitive impairment.


mental retardation: Subnormal intellectual functioning associated with impairment in adaptive behaviour and identified at an early age.


meprobamate: Generic term for Miltown, an anxiolytic, the first introduced and for a time one of the most widely used.


mescaline: A hallucinogen and alkaloid that is the active ingredient of peyote.


mesmerize: The first term for hypnotize, after Franz Anton Mesmer, an Austrian physician who in the late eighteenth century treated and cured hysterical or conversion disorders with what he considered the animal magnetism emanating from his body and permeating the universe.


meta-analysis: A quantitative method of analyzing and comparing various therapies by standardizing their results.


metabolism: The sum of the intracellular processes by which large molecules are broken down into smaller ones, releasing energy and wastes, and by which small molecules are built up into new living matter by consuming energy.


metacognition: The knowledge people have about the way they know their world, for example, recognizing the usefulness of a map in finding their way in a new city.


methadone: A synthetic addictive heroin substitute for treating heroin addicts that acts as a substitute for heroin by eliminating its effects and the craving for it.


methedrine: A very strong amphetamine, sometimes shot directly into the veins.


3-methoxy-4-hydroxyphenylethylene glycol (MHPG): A major metabolite of norepinephrine.


midbrain: The middle part of the brain that consists of a mass of nerve fibre tracts connecting the spinal cord and pons, medulla, and cerebellum to the cerebral cortex.


migraine headaches: Extremely debilitating headaches caused by sustained dilation of the extracranial arteries, the temporal artery in particular; the dilated arteries trigger pain-sensitive nerve fibres in the scalp.


mild mental retardation: A limitation in mental development measured on IQ tests at between 50–55 and 70; children with such a limitation are considered the educable mentally retarded and are usually placed in special classes.


milieu therapy: A treatment procedure that attempts to make the total environment and all personnel and patients of the hospital a therapeutic community, conducive to psychological improvement; the staff conveys to the patients the expectation that they can and will behave more normally and responsibly.


Miltown: The trade name for meprobamate, one of the principal anxiolytics.


Minnesota Multiphasic Personality Inventory (MMPI): A lengthy personality inventory by which individuals are diagnosed through their true–false replies to groups of statements indicating states such as anxiety, depression, masculinity–femininity, and paranoia.


mixed design: A research strategy in which both classificatory and experimental variables are used; assigning people from discrete populations to two experimental conditions is an example.


mixed receptive-expressive language disorder: Difficulties producing and understanding spoken language.


M’Naghten rule: An 1843 British court decision stating that an insanity defence can be established by proving that the defendant did not know what he or she was doing or did not realize that it was wrong.


modelling: Learning by observing and imitating the behaviour of others.


moderate mental retardation: A limitation in mental development measured on IQ tests between 35–40 and 50–55; children with this degree of retardation are often institutionalized, and their training is focused on self-care rather than on development of intellectual skills.


mongolism: See Down syndrome.


monism: Philosophical doctrine that ultimate reality is a unitary organic whole and that therefore mental and physical are one and the same. Contrast with dualism.


monoamine: An organic compound containing nitrogen in one amino group (NH). Some of the known neurotransmitters of the central nervous system, called collectively brain amines, are catecholamines and indoleamines, which are monoamines.


monoamine oxidase (MAO): An enzyme that deactivates catecholamines and indoleamines within the presynaptic neuron, indoleamines in the synapse.


monoamine oxidase inhibitors: A group of antidepressant drugs that prevent the enzyme monoamine oxidase from deactivating neurotransmitters of the central nervous system.


monozygotic (MZ) twins: Genetically identical siblings who have developed from a single fertilized egg; sometimes called identical twins.


mood disorders: Disorders in which there are disabling disturbances in emotion.


moral anxiety: In psychoanalytic theory, the ego’s fear of punishment for failure to adhere to the superego’s standards of proper conduct.


moral treatment: A therapeutic regimen, introduced by Philippe Pinel during the French Revolution, whereby mental patients were released from their restraints and were treated with compassion and dignity rather than with contempt and denigration.


morbidity risk: The probability that an individual will develop a particular disorder.


morphine: An addictive narcotic alkaloid extracted from opium, used primarily as an analgesic and as a sedative.


motor skills disorder: A learning disability characterized by marked impairment in the development of motor coordination that is not accounted for by a physical disorder such as cerebral palsy.


mourning work: In Freud’s theory of depression, the recall by a depressed person of memories associated with a lost one, serving to separate the individual from the deceased.


multi-axial classification: Classification having several dimensions, each of which is employed in categorizing; DSM-IV is an example.


multicultural counselling and therapy: Treatments with interventions that have been modified to address issues, beliefs, and dialogues that characterize people from various cultures.


multifactorial: Referring to the operation of several variables influencing in complex fashion the development or maintenance of a phenomenon.


multimodal therapy: A cognitive-behavioural therapy introduced by Arnold Lazarus, which employs techniques from diverse approaches in an effort to help people make positive changes in their BASIC IB: behaviour, affects, sensations, images, cognitions, interpersonal relationships, and biological functioning.


multiple personality disorder (MPD): See dissociative identity disorder (DID).


multiple-baseline design: An experimental design in which two behaviours of a single person are selected for study and a treatment is applied to one of them. The behaviour that is not treated serves as a baseline against which the effects of the treatment can be determined. This is a common design in operant conditioning research.


mutism: The inability or refusal to speak.


myocardial infarction: Heart attack. See coronary heart disease.