random allocation: refers to the how experimenters divide participants into each experimental condition, to reduce any bias in the distribution of participantcharacteristics.

random sample: a technique for obtaining participants, whereby every member of the population has an equal chance of being selected 

range: a descriptive statistic that shows the difference between the highest and the lowest scores in a data set.

rapid eye movement (REM) sleep: refers to the phase of sleep, characterised by eye movements and dreaming. In adults, REM sleep alternates with other periods of sleep (non-REM sleep) over a 9O-minute cycle. REM sleep is also accompanied by an increase in heart rate and blood pressure, and faster and more irregular breathing patterns.

rating scale: refers to the appraisal of a person or behaviour along a specific scale.

ratio data/scale: an interval scale that has a true zero point (eg. temperature).

rational: consistent with or based on or using reason; "rational behavior".

rational-emotive therapy: a form of therapy developed by Ellis which focuses changing irrational beliefs and faulty interpretations, which result in negativeemotions and severe anxiety.

rationalisation: a defence mechanism whereby behaviour is explained and justified by offering a reason acceptable to the ego in place of the true reason.

reaction formation: a defence mechanism whereby a person a behaviour is displayed that is the opposite of a forbidden impulse. An example would be a man who deals with his homosexual feelings by displaying external resentment towardshomosexuals.

reaction time: time taken to respond to a stimulus, measured by the interval between the stimulus and the response.

realistic conflict theory: an account of prejudice and discrimination that proposes intergroup conflict and antagonism occurs when groups are competing for scarce resources.

reality principle: in Freud's theory, the constraints and set of rules that govern theego, delaying the ids gratification, by recognition of the demands of the real world.

reasoning: is the mental (cognitive) process of looking for reasons for beliefs, conclusions, actions or feelings.

rebound: the symptoms that the medicine was going to cure returns when one stops taking the medicine and sometimes extra much so during the time just after one has gone off the medicine.

recall: in memory, the active retrieval of information.

recency effect: improved memory for list of words at the end of a list than those in the middle of the list.

recentring: in Gestalt theory, developing an alternative ?a target="_blank" href="https://itseducation.asia/psychology/m.htm#mental_set">mental set?for a situation, such as when trying to solve a problem.

recidivism: reverting back to crime, for instance after being released from prison.

reciprocal altruism: in evolutionary psychology, the concept that individuals performance altruistic behaviour if the expected benefit of future help from the strangers surpasses the short-term cost of helping.

recognition: in memory, the process of identifying presented information as familiar and having been experienced before.

reconstructive memory: an account of piecing together and reassembling stored information during recall, and stored knowledge, expectations and beliefs are used to fill gaps and produce a coherent memory representation.

recovered memories: adults recover early repressed memories (often sexual abuse), which are often cited as the cause of a problem (e.g. eating disorder)

reflex: an unlearned response that is triggered by specific environmental stimuli, e.g. as a baby's sucking on an object placed in the mouth.

refractory period: refers to the period following an action potential when a particular section of a nerve cell cannot be stimulated.

regression: in Freudian theory, a defence mechanism whereby a individual reverts to a behaviour of an earlier developmental period to prevent anxiety and satisfy current needs.

rehearsal: refers to the cognitive process involving the repetition of an item in order to maintain it in short-term memory.

reinforcer: in conditioning, any stimulus, that after following a response, increases the probability of that response occurring.

relapse: return to drug use by a user who has previously recovered. Alternative definition: The symptoms that the medicine was going to cure returns when one stops taking the medicine and sometimes extra much so during the time just after one has gone off the medicine.

related t-test: a parametric inferential statistical test. Used with interval or ratio data, a repeated measures design (or matched pairs), to investigate any difference in the effect each level of the independent variable has on the dependent variable.

relaxation training: procedures that target to reduce and relax muscle tension, heart rate and cortical activity. This is evident in systematic desensitisation.

reliability: a measure of consistency, to represent the degree to which replications of a test or method produces similar data scores.

repeated measures design: (within-subjects or related design) experimental design in which each individual participates in every level of the independent variable.

repression: defence mechanism whereby memories, feelings or ideas associated with pain or guilt are blocked from conscious awareness.

research: the process of gaining knowledge, either by an examination of appropriate theories or through empirical data.  In psychology, the term is used to refer to an investigative process such as the experiment or the case study.

resistance: in psychoanalysis, inability or unwillingness of a patient to accept the analysts interpretations of their behaviour and to discuss certain ideas or experiences.

responder bias (participant reactivity): Arial"> tendency of a participant to produce biased responses as a result of wanting to appear socially desirable or to be in line with what the experimenter wants.

restoration accounts of sleep: the hypothesis that the purpose of sleep is to restore and repair the body.

reticular formation: a diffuse network of nerve fibres which runs through the brain stem and limbic system, with connections both up to the cortex and down to the spinal cord; that alerts the cerebral cortex to incoming sensory signals and serves to regulate arousal levels, maintain consciousness and awakening from sleep.

retina: the light sensitive part of the eye, that is comprised of three layers of neural tissue, including photoreceptors that convert light into neural responses to be passed to the brain via the optic nerve.

retrieval: the process and recovery of a stored item from memory.

retrieval cues:internal or external stimuli that aid memory retrieval.

retrograde amnesia: the inability to recall events before the cause of the amnesia, e.g. brain injury.

retrospective study: a study which assesses the impact of early experience on later development looking back from the time of the specified effect to the early experience.

reward: any event which is pleasurable or satisfying to the organism (for example, food to a hungry animal)

rewards-cost model: theory by Piliavin that proposes that altruistic behaviour is determined by weighing up the rewards and costs of helping and not helping.

risky shift: refers to the fact that people tend to make riskier decisions when they are members of a group than they would if they made the same decision independently.

ritalin: a drug whose action resembles that of the amphetamines. It has been controversially used in the treatment of children suffering from attention deficit (hyperactivity) disorder.

Rogers (1902-1987): was one of the original founders of the humanistic perspective. His theories encompassed the importance of unconditional and conditional positive regard in development of the 'self concept' and 'conditions of worth' set by others. His work has been applied to a range of domains, particularly in therapy through his development of 'client-centred' (now class="d-title" named 'person-centred'therapy.

rods (and cones): a type of receptor cell found in the retina of the eye. Rods are critical for sight during dim illumination, whereas cones are more active in good light conditions. Individuals who lack rods (or have rods that don't function) suffer from night blindness, and cannot see properly in dim light.

role conflict: a situation where an individual occupies two roles at the same time, where each role is incompatible to the expectations of the other.

role model: a person whose behaviour is observed and imitated.

Rorschach test: a type of projective test that consists of ten bilaterally symmetrical inkblots. Participants responses and interpretations are assumed to reveal of various characteristics such as emotional responsiveness andpersonality.