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vagina: The sheath-like female genital organ that leads from the uterus to the external opening.

vaginal barrel: The passageway of the vaginal canal leading from the external opening to the uterus.

vaginal orgasm: Sexual climax experienced through stimulation of the vagina.

vaginal plethysmograph: A device for recording the amount of blood in the walls of the vagina and thus for measuring arousal.

vaginismus: Painful, spasmodic contractions of the outer third of the vaginal barrel, which make insertion of the penis impossible or extremely difficult.

validity: Different types of validity include internal, the extent to which experimental results can be confidently attributed to the manipulation of the independent variable; external, the extent to which research results may be generalized to other populations and settings. Validity as applied to psychiatric diagnoses includes concurrent, the extent to which previously undiscovered features are found among patients with the same diagnosis; predictive, the extent to which predictions can be made about the future behaviour of patients with the same diagnosis; etiological, the extent to which a disorder in a number of patients is found to have the same cause or causes. Validity as applied to psychological and psychiatric measures includes content validity, the extent to which a measure adequately samples the domain of interest; criterion, the extent to which a measure is associated in an expected way with some other measure (the criterion). See also construct validity.

Valium: An anxiety-reducing drug, or anxiolytic; one of the benzodiazepines.

value self-confrontation: A procedure whereby a person’s values and behaviour are changed by demonstrating that the values of people he or she wishes to emulate are different from the ones currently held by the person.

variable: A characteristic or aspect in which people, objects, events, or conditions vary.

vasoconstriction: A narrowing of the space within the walls (lumen) of a blood vessel; implicated in diseases such as hypertension.

vicarious learning: Learning by observing the reactions of others to stimuli or by listening to what they say.

videotape reconstruction: A technique for assessing a person's thoughts and feelings. It involves having the person recall his or her reactions while watching a videotape of a previous time when they were engaged in a task.

Vineland Adaptive Behaviour Scale: An instrument for assessing how many age-appropriate, socially adaptive behaviours a child engages in.

viscera: The internal organs of the body located in the great cavity of the trunk proper.

vitamins: Various organic substances that are, as far as is known, essential to the nutrition of many animals, acting usually in minute quantities to regulate various metabolic processes.

voyeurism: Marked preference for obtaining sexual gratification by watching others in a state of undress or having sexual relations.

vulnerability schema: The schema of people who are socially anxious and who generally think about danger, harm, and unpleasant events that may come to them.