Dictionary of Terms
Random Assignment An assignment of subjects to the various groups of an experiment by random means, thereby ensuring comparable groups.
Range The difference between the highest score and the lowest score of a sample.
Rapid Eye Movement (REM) Sleep A period of sleep during which dreaming, rapid eye movements, and muscular paralysis occur and the EEG shows beta activity.
Rational-Emotive Therapy Therapy based on the belief that psychological problems are caused not by upsetting events but by how people think about them.
Rationalization A defense mechanism that justifies an unacceptable action with a more acceptable, but false, excuse.
Reaction Formation A defense mechanism that involves behaving in a way that is the opposite of how one really feels because the true feelings produce anxiety.
Reactive Schizophrenia According to Bleuler, a form of schizophrenia characterized by rapid onset and brief duration; he assumed the cause was stressful life situations.
Reality Principle The tendency to satisfy the idís demands realistically, which almost always involves compromising the demands of the id and superego.
Receiver Operating Characteristic Curve (ROC curve) A graph of hits and false alarms of subjects under different motivational conditions; indicates peopleís ability to detect a particular stimulus.
Recency Effect The tendency to recall later information. In the memorization of a list of words, the recency effect is evidenced by better recall of the last words in the list.
Receptive Field That portion of the visual field in which the presentation of visual stimuli will produce an alteration in the firing rate of a particular neuron.
Receptor Cell A neuron that directly responds to a physical stimulus, such as light, vibrations, or aromatic molecules.
Receptor Molecule A special protein molecule located in the membrane of the postsynaptic neuron that responds to molecules of the transmitter substance. Receptors such as those that respond to opiates are sometimes found elsewhere on the surface of neurons.
Recessive Allele The form of the gene that does not influence the expression of a trait unless it is paired with another recessive allele.
Reciprocal Altruism Altruism in which people behave altruistically toward one another because they are confident that such acts will be reciprocated toward either them or their kin.
Reciprocal Determinism The idea that behavior, environment, and person variables, such as perception, interact to determine personality.
Reciprocity The tendency to return, in kind, favors that others have done for us.
Reflex An automatic response to a stimulus, such as the blink reflex to the sudden approach of an object toward the eyes.
Regulatory Behavior A behavior that tends to bring physiological conditions back to normal, thus restoring the condition of homeostasis.
Reliability The repeatability of a measurement; the likelihood that if the measurement was made again it would yield the same value.
REM Sleep Behavior Disorder A neurological disorder characterized by absence of the paralysis that normally occurs during REM sleep; the patient acts out his or her dreams.
Replication Repetition of an experiment or observational study to see whether previous results will be obtained.
Representativeness Heuristic A general rule for decision making through which people classify a person, place, or thing into the category to which it appears to be the most similar.
Repression The mental force responsible for actively keeping memories, most of which are potentially threatening or anxiety-provoking, from being consciously discovered.
Reproductive Strategies Different systems of mating and rearing offspring. These include monogamy, polygny, polyandry, and polygamy.
Reproductive Success The number of viable offspring an individual produces relative to the number of viable offspring produced by other members of the same species.
Resistance A development during therapy in which the client becomes defensive, unconsciously attempting to halt further insight by censoring his or her true feelings.
Resistant Attachment A kind of attachment in which infants show mixed reactions to their mothers. They may approach their mothers upon their return but, at the same time, continue to cry or even push their mothers away.
Response Cost A consequence that decreases the frequency of response that is regularly and reliably followed by the termination of an appetitive stimulus.
Retina The tissue at the back inside surface of the eye that contains the photoreceptors and associated neurons.
Retinal Disparity The fact that points on objects located at different distances from the observer will fall on slightly different locations on the two retinas; provides the basis for stereopsis, one of the forms of depth perception.
Retrieval Cues Contextual variables, including physical objects, suggestions, or other verbal stimuli, that improve the ability to recall information from memory.
Retrieval The active processes of locating and using stored information.
Retroactive Interference Interference in recall that occurs when recently learned information disrupts our ability to remember older information.
Retrograde Amnesia The loss of the ability to retrieve memories of oneís past, particularly memories episodic or autobiographical events.
Retrospective Study A research technique that requires subjects to report what happened in the past.
Reuptake The process by which a terminal button retrieves the molecules of transmitter substance that it has just released; terminates the effect of the transmitter substance on the receptors of the postsynaptic neuron.
Rhodopsin The photopigment contained by rods.
Rod A photoreceptor that is very sensitive to light but cannot detect changes in hue.
Rorschach Inkblot Test A projective test in which a person is shown a series of symmetrical inkblots and asked to describe what he or she thinks they represent.
Round Window An opening in the bone surrounding the cochlea. Movements of the membrane behind this opening permit vibrations to be transmitted through the oval window into the cochlea.