habit: a behaviour that develops as a result of experience and occurs almost automatically. For instance, behaviours that satisfy psychological cravings (through for example chain smoking). 

habituation: the process whereby an organism’s response to repeated stimulitemporarily decreases.

hallucination: false perceptions that occur with the lack of relevant sensory stimuli, such as hearing voices.

halo effect: a form of perceptual bias which transpires when our rating of a person on one characteristic as being positive or negative of a person affects the rating of the individual on other characteristics (similarly positive or negative). For instance, if an individual is viewed as intelligent, the rater also perceives them to be friendly. 

hardiness: personality factors (control, commitment and challenge) identified by Kobasa that help mitigate against negative effects of stress.

health behaviours: activities that maintain or improve health.

health promotion: refers to strategies and tactics that help enable people to gain control of, and therefore enhance, their health through changes in lifestyle and preventative practices, significantly reduce the risk of illness.

health psychology: area of psychology that aims to understand why people become ill, how they stay healthy and how they respond and cope with illness.

hedonic relevance: the likelihood of making a dispositional attribution if we are directly involved and the consequences are serious. Therefore, we are likely to overstate the influence of dispositional factors, and underestimate the importance of situational factors.

hedonism: a belief that all behaviour is, or should be, motivated toward the pursuit of pleasure and the avoidance of pain.

Heider (1896-1988): Austrian psychologist who focused on interpersonal relationships, proposing balance theory and attribution theory.

helping behaviour: see altruism (human) and bystander behaviour

heredity: the biological transmission of inherited characteristics from parents to offspring.

Heritability estimate: measured by H, the heritability ratio, a statistical estimate of the degree of inheritance of a specific trait or behavior, measured by the degree of similarity between individuals who share differing amounts of genetic similarity. 

hertz:a measure of frequency, cycles per second.                                                                                                                       

heterosexuality: an attraction to the opposite sex.

heuristic: cognitive strategies, or rules of thumb? Heuristics provide informal strategies to aid problem solving, which are usually more successful than random search, but less effective than algorithms..

hierarchy of needs: Maslow's model of basic human motives, which he saw as organised in a hierarchical structure; needs range from the bottom level ofphysiological (e.g. food, water, shelter) to the highest level - self-actualisation. Needs at each level of the hierarchy must be met before the next level can be achieved.

hippocampus: part of the limbic system, located in the medial temporal lobe. Important for spatial orientation and navigation, and is crucial for memory, in particular the transfer of information from short-term to long-term memory.

histogram: used to represent the distribution of scores for one set of data. The data must be numerical and there should be no gaps between the bars.

HIV (human immunodeficiency virus): a virus that attacks white blood cells in the blood, reducing the bodys ability to fight off illness. HIV causes AIDS and can be transmitted through unprotected sex, by drug users who use similar equipment and from an infected mother to her unborn child.

holistic: used to describe an approach that focuses on the whole person, rather than their constituent parts.

Holmes and Rahe (1967):  constructed the Social Readjustment Rating Scale to measure the impact of significant life events.

homeostasis: a state of equilibrium or balance of the internal conditions of the body.

homeostatic drive theory (of eating and drinking): refers to the proposition that eating and drinking are driven by internal homeostasis.

homosexuality: a term used to describe either sexual contact with members of the same sex, or a sexual preference for one's own sex.

hormone: chemical messengers, secreted by the endocrine glands, that affect a range of aspects of metabolism and body functioning, for instance, mood and sexual characteristics.

hostile aggression: a form of aggression to cause intentional harm of injury to another person or object.

humanistic psychology: a perspective in psychology, that views every individual as unique and as possessing an inherent capacity for making rational choices, positive growth and ultimately, maximum potential.

humanistic therapies: treatment whereby the therapist seeks see the world through the clients perspective, and to allow the client to view their situations with greater insight and acceptance, with an ultimate goal of growth and fulfilment. Examples of humanistic therapies include client-centred therapy.

Huntington's disease (HD): is a fatal heredity disease that destroys neurons in areas of the brain involved in the emotions, intellect, and movement.

hyperactivity: a higher degree of inappropriate motor activity than is considered typical for a particular age group. See Attention Deficit Disorder (ADD).

hyperfocus: is an intense form of mental concentration or visualisation that focuses consciousness on a narrow subject, or beyond objective reality and onto subjective mental planes, daydreams, concepts, fiction, the imagination, and other objects of the mind.

hypothetical: based on assumption rather than fact or reality.

hypnosis: the induction of an altered state of consciousness, manifested in a sleep-like state or of deep relaxation. Consequently, changes in perception,memory and self-control leave an individual more vulnerable to suggestion. The use of hypnosis in therapy still remains highly controversial, particularly with the occurrence of false memories being recovered?

hypothalamus: part of the brain that is crucial in control the autonomic nervous system, maintaining homeostasis and regulating motivated behavior (e.g. appetite) and hormonal functions.

hypothesis: a testable statement, predicting the relationship between two (or more) variables, which can be accepted or rejected as a result of the research outcome.