Find over 25,000 psychological definitions


n. any of a group of methylated derivatives of xanthines (stimulant plant alkaloids) with similar pharmacological actions. The most common are caffeine (1,3,7-trimethylxanthine), the active ingredient in coffee; theobromine (3,7-dimethylxanthine), the active ingredient in cocoa; and theophylline (1,3-dimethylxanthine), the active ingredient in tea. At low doses, methylxanthines cause CNS stimulation and arousal; at high doses, anxiety, agitation, and coma may result. Methylxanthines also relax bronchial muscles: Some (e.g., theophylline) have been used in the medical management of reactive airway disease, although they have now largely been supplanted by newer agents.

Browse dictionary by letter

a b c d e f g h i j k l m n o p q r s t u v w x y z

Psychology term of the day

June 25th 2024

population distribution

population distribution

the arrangement of scores or responses on a variable for a complete population of interest. For example, a researcher could graph the income distribution of all families in a town; in contrast, the sample distribution would show the incomes of only a specific subset of families.