A psychological disorder which is severe enough to disrupt a person’s everyday life and require institutional treatment. Apart from organic causes like BRAIN DAMAGE it has been thought by many psychologists that a psychosis is a severe form of NEUROSIS. More recently there has been a tendency to regard biochemical factors as being important in at least some forms of psychosis. It is characterised by a lack of contact with (other people’s) reality.

A school of PSYCHOLOGY which began in the early part of the 20th Century as a reaction against the behavioural psychology of PAVLOV and WATSON, gestalt psychology insisted that psychological PHENOMENA should be treated as GESTALTEN, which could not be equated with the elements that made them up.

The first Gestalt psychologists Kofka, KOHLER and Wertheimer arrived at their ideas after studies of PERCEPTION: they were struck by the way the BRAIN organised dots of light into visual patterns or musical notes into melodies. Kohler later branched out into studies of INSIGHT LEARNING (see the AHA REACTION) in apes and later Gestaltists like Goldstein and LEWIN have extended Gestalt ideas into areas of PERSONALITY and SOCIAL PSYCHOLOGY.

Gestalt thinking on perception is now largely accepted by psychologists, and its approach is very much in tune with the COGNITIVE REVOLUTION, though some people would argue that there are areas of human BEHAVIOUR which can still best be understood by an analysis of the elements involved.

A form of mathematics used on data gathered in studying BEHAVIOUR and by which investigators evaluate their findings and make inferences of wider implication than their study sample.

Paying attention to people at work improves their performance these were the findings of a study done at the Hawthorne works of the Western Electric Company in Illinois in the 1920s. Various attempts by the management to improve workers’ conditions were made; they included changes in light, rest breaks, hours of work and systems of payment. Each of these changes resulted in an increase in productivity and so did a return to the original conditions of work. The investigators concluded that the changes in the external environment had not influenced the workers’ performance so much as their PERCEPTION that people were interested in them and their work. An example of SOCIAL FACILITATION.

A test that is supposed to measure INTELLIGENCE. Its purpose is to discriminate between people who score high and people who score low (i.e. high and low IQ) for the purpose of assigning them to various educational, occupational and social categories. High scores are supposed to denote high intelligence and low scores the opposite, but in the absence of an agreed definition of intelligence, the OPERATIONAL DEFINITION becomes circular people score high on intelligence tests because they are highly intelligent because highly intelligent people score high on intelligence tests. There is also a great deal of evidence that intelligence tests tend to be biased in favour of white, urban, middle-class people in their selection of test items.

The most important concept of DYNAMIC PSYCHOLOGY and in particular of PSYCHOANALYSIS; the region of the PSYCHE that contains impulses and desires which are too threatening to be allowed into CONSCIOUSNESS and from which they have been REPRESSED or INHIBITED from entering. The effects of this repression and inhibition are expressed in consciousness as NEUROTIC BEHAVIOUR. While FREUD did not discover the unconscious (and never claimed to have done so) he systematically probed the dynamic mechanisms involved in its relationship with the conscious psyche and did more than anyone to expose the great amount of irrationality in human affairs.

A SAMPLE chosen at random from a POPULATION (i.e. where everyone in a whole population has an equal chance of being chosen) so that inferences can be made to the population from findings about the sample without the dangers of a BIASED SAMPLE.