narcolepsy: an uncommon sleep disorder, narcolepsy is marked by recurring irrepressible attacks of sleep during normal waking hours, as well as by cataplexy, sleep paralysis and hallucinations.

nativism: that aspects of cognitive processes and behaviour are innate.

natural experiment:   experiment whereby the researcher cannot directly control the independent variable nor participant allocation to conditions.

naturalistic observation: a study whereby the observer does not manipulate any variables within a natural setting where behaviour takes place, by merely observing and recording. Observational technique can be divided into participant observation (where the researcher takes contributes to a groups behaviour, whilst participants are unaware of the observers true purpose or identity) and non-participant observation (whereby the researcher remains inconspicuous).

natural selection: a principle of Darwins theory of evolution that animals that have adapted better to their envir onment allows some members of a species to produce more offspring that others, as a result of possessing advantageous traits that improve survival chances and increase reproductive success.

nature vs nurture: a debate within psychology that explores the extent to which specific aspects of behaviour are inherited or learnt as a result of environmental influences.

negative correlation: a relationship between two measured variables where as one variable increases the other variable decreases.

negative emotions: can be described as any feeling which causes you to be miserable and sad. These emotions make you dislike yourself and others, and take away your confidence.

negative reinforcement: in operant conditioning, a method to increase the probability and strength of a response by removing or withholding an aversive stimuli  (negative reinforcer)

negative-state relief: proposal that we assist others in order to alleviate negative feelings, for instance to lessen feelings of guilt or sadness.

negative symptoms: in abnormal psychology, particularly with reference to schizophrenia, deficits in functioning that reveal the absence of expected behaviours, for instance, flat affect and limited speech.

neo-Freudian: a term that is used to characterise a group of Freudian-influenced psychologists who, whilst accepting the concept of unconscious conflict, disagree over the extent of the influence of bodily pleasures or frustrations and have placed greater emphasis on other aspects of behaviour and experience. Famous neo-Freudians include Adler and Jung.

neonate research: investigations carried out using newborn infants.

nerve impulse: the electrical signal produced when a neuron is active, which passes from the dendrites, along the axon, to the specific terminals.

neurological disorder: disturbance in structure or function of the nervous system resulting from developmental abnormality, disease, injury, or toxin.

neuron: ('nerve cell') a cell of the nervous system that functions to receive and communicate information to other cells .

neurophysiology: study of the workings of the nervous system including brain function.

neuroscience:a branch of psychology, also called physiological psychology. Neuroscience is the study of the functioning of the nervous system which includes the structures and functioning of the brain and its relationship to behaviour.

neurosis: a mental or personality disturbance not attributable to any known neurological or organic dysfunction.

neuroticism:is a fundamental personality trait in the study of psychology. It can be defined as an enduring tendency to experience negative emotional states.

neurotransmitter: chemical messengers released by the terminals of a neuron which cross between the synapses of neurons, to have an excitatory or inhibitory effect on an adjacent neuron.

neutral stimulus: in classical conditioning, a stimulus which initially fails to elicit a response, but as conditioning continues, becomes a conditioned stimulus.

Nietzsche (1844-1900): Nineteenth-century philosopher.

nominal data: data that is organised on the basis of category.

nomothetic: refers to a perspective or method that attempts to establish general patterns of behaviour that can be extended to all members of a population.

non-conformity: refers to situations whereby an individual withstands the tendency to conform to the attitudes, judgements or behaviour of the majority.

non-directional hypotheses (two-tailed hypotheses): states that the independent variable will have an effect upon the dependent variable, but does not specify the direction (e.g. higher/lower scores) of effect upon the dependent variable.

non-invasive procedures: procedures (e.g. MRI, PET scans) for imaging the brain do not require direct contact and interference with brain tissue.

non-participant observation: the observer remains inconspicuous so that the behaviour of the participants is not affected.

non-verbal communication: generally referred to as 'body language' by non-psychologists, refers to any form of communication that is not conveyed through verbal or written language, for instance posture and facial expressions.

Norepinephrine or 'noradrenaline': a neurotransmitter that is important in the regulation of mood; disturbances in its tracts have been implicated in depression and mania.

normal distribution: a type of frequency distribution which is represented by a symmetrical, bell-shaped curve, whereby the mean, mode and median all lie at the highest point of the curve.

normative influence: an explanation of conformity which occurs as a result of a desire to be accepted in a group and liked by others.

null hypothesis: the hypothesis that any difference between the independent and dependent variables merely occur as a result of chance, rather than as any significant effect of the independent variable.