title: A rapid effect of caffeinated beverages on two choice reaction time tasks.
abstract: Though consumers of tea and coffee can report feeling beneficial subjective effects of consumption virtually immediately, tests for objective effects of caffeine immediately post-consumption have been rare. Two experiments examined caffeine's ability to influence reaction time in choice reaction time tasks, using a dose of caffeine typical of a cup of tea or instant coffee, and testing at short post-consumption delays. Two groups of participants were given 60 mg of caffeine, after overnight abstinence, either in a hot tea drink, or a hot water drink. Two control groups also received hot tea or water, but without caffeine. In Experiment 1, participants were given a keypress task before the drink (baseline), immediately after the drink, and 40 min after the drink. In Experiment 2, a touch-screen test was given either 1, 14, or 27 min post consumption. Caffeine was found to reduce the effect of a distracter on reaction time in the keypress test and to reduce reaction time in a component of the touch-screen task; however, in neither experiment were these effects significantly modulated by post-consumption delay length. Thus, the speed of caffeine's action on psychomotor performance was shown to be on the order of minutes.
authors.affiliation: Army Research Institute, Simulator Systems Research Unit, 12350 Research Parkway, Orlando, FL 32826, USA. pjdurlach@hotmail.com
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Durlac
authors.forename: Robert
authors.initials: R
authors.lastname: Edmunds
authors.forename: Louise
authors.initials: L
authors.lastname: Howard
authors.forename: Steven P
authors.initials: SP
authors.lastname: Tipper
mesh_terms: D000293:Adolescent; D000328:Adult; D001628:Beverages; D002110:Caffeine / Q000008:administration & dosage*; D002755:Choice Behavior; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011340:Problem Solving; D011930:Reaction Time / Q000187:drug effects*; D014867:Water
chemical_list: D014867:Water; D002110:Caffeine