Glossary
valid conclusion: the conclusion that follows inevitably from the premises and the application of logic
validity: (1) a general term referring to the extent to which a study investigates what it purports to measure. Internal validity refers to the extent to which a study correctly tests the intended predictions. External validity refers to the extent to which the results of a study can be generalised to real, (2) evidence that a study allows correct inferences about the question it was aimed to answer. Evidence that a test measures what it set out to measure conceptually
variability: the spread of scores around their mean
variable interval schedules (VI): in operant conditioning, when a reinforcer is delivered after a varied interval around an average time if a response has been made
variable ratio schedule (VR): in operant conditioning, when a reinforcer is delivered after a varied number of responses around an average
variable: anything that can be measured and can differ across entities or across time
variance: a measure of the average variability of scores around their mean that is not in the original units of measurement. It is the sum of squared errors divided by the number of observations or values used to calculate that total
vascular theory of emotion: the suggestion that changes in facial expressions influence the blood vessels that regulate brain temperature. Increases in brain temperature are associated with negative emotions and decreases with positive ones
vasopressin: antidiuretic hormone. Reduces the amount of fluid going to the bladder and conserves water
ventral tegmental area (VTA): part of the mesolimbic system
ventromedial hypothalamus (VMH): part of the hypothalamus involved in feeding behaviour
verbal memory: the memory system or systems which deal with language-based material
verb-island hypothesis: the suggestion that children have difficulty working out that different verbs follow the same grammatical rules
vesicles: a small intracellular, membrane-enclosed sac that stores and/or transports neurotransmitter substance
vigilance: an attentional state in which a person is waiting for an indefinite period of time to detect an event or signal
visual (or direct) route to reading: the route to accessing the meaning of a word which uses the written form to directly access the word’s meaning in the mental lexicon
visual illusions: visual percepts which are systematically inaccurate representations of the distal stimulus
visual search: an experimental technique in which the participant is required to search for a particular target in an array of potential targets
visual sensory memory: see iconic memory
visuospatial scratchpad: the component of working memory which deals with visual and spatial information
Völkerpsychologie: the study of the collective mind. Early precursor to social psychology from Germany in the 1860s
volunteer sampling: a sample consisting of people who have volunteered to take part in research
vulnerability factors: factors that make an individual susceptible to the development of a psychopathology (e.g. childhood abuse and neglect is a vulnerability factor for many later life psychopathologies)