magnetic resonance imaging (MRI): is a painless diagnostic tool which uses a magnetic field and radio waves to see inside the body without using x-rays or surgery; a computer then interprets the radio waves and creates a picture of the internal body tissues.

maladaptive behavior: behavior that bring stress.

manic depressive disorder: see bipolar disorder/depression

manifest content: in Freud's theory of dreams, the superficial, symbolic form of a dream which the conscious mind is aware of, both during sleep and on waking, which is assumed to hide the true meaning.

mania: an emotional state typified by intense elation, unrestricted euphoria, hyperactivity, excessive talkativeness, grandiose feelings or thoughts and disrupted thought processes.

Mann-Whitney U test: A non-parametric inferential statistical test. Employed with ordinal data and independent groups.

Maslow (1908-1970) : a humanistic psychologist who proposed humanistic psychology as a third force?in reaction to the perspectives of psychoanalysis andbehaviourism, and the belief that humans are essentially good. Maslows 'hierachy of needs'proposes a psychological structure of needs and tendencies, whereby basic needs (e.g. hunger) must be satisfied before higher needs (e.g. self-esteem) can be achieved, towards an ultimate goal of self-actualisation.

matched pairs design : participants in different conditions are matched according to certain characteristics, e.g. age or gender.

maternal deprivation: children deprived of maternal care and love in early childhood are likely to suffer some degree of emotional, social or intellectualretardation in later life. Prolonged separation (resulting in an attachment bond breaking) was proposed by Bowlby to cause the deprivation syndrome.

maturation: processes in development which seem to be relatively independent of environmental influences, such as depth perception and walking; implied in the term is the assumption that the characteristics are governed by heredity.

mean: measure of central tendency, calculated by the total sum of all the scores, divided by the total number of scores.

median: measure of central tendency that utilises the mid-point of the ranked data.

means-ends analysis: a type of problem solving strategy that is used in computer programs, whereby problems are broken down into their constituent parts and then solved in turn until the solution is found.

measure of dispersion: a measurement of the spread or variability in a set of scores.

medical model: a theory of abnormal behaviour which assumes that all such disorders have physiological causes.

medical model of abnormality: views mental disorders as having physiologicalcauses , e.g. genetic and biochemical.

meditation: refers to techniques that focus the mind and promote a state of calmness so that the mind and body can be brought into greater harmony to facilitate health and healing.

medulla: a small region of the brain stem, that regulates basic bodily processes including breathing and the heartbeat.

MEG (magnetoenecephalography): non-invasive technique for visualising (imaging) the brain by recording tiny magnetic fields produced by active neurons.

melancholia: originally first described by the Greeks and Romans, and characterised by a deep and persistent sadness and now corresponds closely to depression.

memory: the capacity to encode, retain, store and retrieve information.

mental: refers to the mind, the collective aspects of intellect and consciousness.

mental set: in Gestalt theory , the schema used to organise perception of a new problem. 

mental age: the level of intellectual functioning which is suitable for children of a particular age. Typically, mental age is equivalent to chronological age, but if a child is of lower/higher intelligence the mental age will be accordingly lower/higher than chronological age.

mental disorders: anxiety disorders, conduct disorder, depressive disorders,oppositional defiant disorder, pervasive development disorder or Tourette's syndrome.

mental health: a state of psychological and emotional well-being that enables an individual to work, love, relate to others effectively, and resolve conflicts.

mental retardation: individuals who have significantly below average intellectualfunctioning, with IQ scores of 70-75 or below, combined with inability to use adaptive skills.

mere exposure effect: the higher the levels of exposure to a stimulus, the more likely we are to develop a greater attraction to it.

meta-analysis: a statistical technique that involves combining and analysing the data of a number of independent studies.

metabolic: pertaining to all chemical functions within the body.

method of loci: a technique to increase memory effectiveness through memorising a series of different locations (such as rooms in a house) and then imagining an item to be remembered at each location. Items are then recalled by mentally "walking through" the house and "seeing" the item.

midbrain: a region of the brain that relays sound input to the auditory cortex.

milieu therapy: a humanistic approach to the treatment of psychological disorders that emphasises the importance of an institution in recovery. An environment is created whereby staff and patients are viewed as equal, and an atmosphere is fostered of self-respect.

Milgram (1933- 1984): an influential social psychologist who is best known for his controversial study on obedience to authority, under conditions whereby obeying conflicts with personal conscience.

mind: collectively refers to the aspects of intellect and consciousness manifested as combinations of thought, perception, memory, emotion, will and imagination; mind is the stream of consciousness. It includes all of the brain's consciousprocesses.

minority influence: the effect when a persuasive minority exerts pressure to change the attitudes, beliefs or behaviours of the majority. Minorities are most influential when they appear consistent and principled.

misattribution: a mistaken attribution of an emotional response to a cause that did not produce it.

mitosis: a type of cell division within the body, whereby cells divide into other cells, each with the full set of chromosomes. Each of these cells receives an exact copy of the chromosomes in the original cell. During development, mitosis occurs again and again, until finally the adult organism is created.

mnemonics: techniques that improve memory, often through using existing familiar information (e.g. imagery) during the encoding of new information to aid later retrieval and access. See method of loci.

mock juries: a group of participants who are required to imagine and act as members of a jury, to investigate factors affecting the decision making process.

mode: the score that occurs most frequently within a data sample.

modelling: the term used by Bandura to describe the process of learning and socialisation, through observing and imitating others.

monism: the view that mind and body are a single unit.

monozygotic (identical) twins: twins that develop from the same zygote (egg) and therefore share 100 percent of their genes.

mood: mental or emotional state.

mood disorders: a mood disturbance, characterised by emotional extremes, alternating between extreme depression and mania.

moral development: the process through which children learn to understand the differences between right and wrong and can make independent decisions on moral issues.

morality: in the strictest sense of the word, deals with that which is innatelyregarded as right or wrong. The term is often used to refer to a system of principles and judgments shared by cultural, religious, and philosophical concepts and beliefs, by which humans subjectively determine whether given actions are right or wrong.

moral realism: part of Piagets theory of moral development, whereby children understand that the rules of adults are firm and unquestionable. 

moratorium: a term devised by Erikson to describe a period during which adolescents consider various values and goals, in order to understand and establish their own individual identity.

mores: refers to standards of behaviour or customs that are appropriate within a society, and accepted by the majority.

morpheme: the smallest significant unit of speech that conveys meaning.

motivation: an internal state that arouses, drives and directs behaviour, that have been accounted for by physiological explanations (e.g. internal drives such as hunger), behavioural explanations and psychological explanations (e.g. for complex human behaviours, such as the need for achievement).

motive: a specific need or desire, such as hunger or achievement, that energizes and directs behavior.

motor neuron: nerves that transmit messages from the central nervous system (i.e. spinal cord or brain) to individual muscle cells .

MRI: see magnetic resonance imaging.

multiaxial diagnosis: used in the DSM classification system of mental disorders, whereby patients are assessed on a variety of axises (e.g. clinical conditions, psychosocial and environmental factors)

multimodal therapy: a cognitive behavioural therapy developed by Lazarus, which aims to consider all aspects of a disorder. To be effective, seven different dimensions, represented by BASIC IB?(behavior, affects, sensations, images, cognitions, interpersonal relationships, and biological functioning) must be focused on and treated.

multiple personality disorder (MPD): a dissociative disorder, whereby two or more distinct and separate personalities are manifested within the same individual, each displaying different interests, memories and behaviour patterns.

multi-store model of memory: devised by Atkinson and Shiffrin, represents memory as a flow of information in a set sequence between a rigid set of structures, including sensory memory, short-term memory and long-term memory.

myelin sheath: a layer of fatty tissue that covers the axons of nerve cells, insulating the axon from other axons and to increase the conduction of nerve impulses along the axon.