The effects of a low dose of caffeine on cognitive performance.

There is little evidence concerning the effects of caffeine in doses typical of one cup of tea. The present study investigated the effect of 60 mg caffeine, consumed in either tea or hot water, on performance on a subset of the CANTAB test battery. Eight males participated in a practice session and four test sessions. In each test session, the participant consumed a different hot beverage and then, over approximately 90 min, completed nine tests from the CANTAB battery. The four beverages were created by crossing beverage identity (tea or hot water) and caffeine dose (0 or 60 mg). Significant speeding of reaction time by caffeine consumption was found in pattern recognition, delayed match to sample, and match to sample visual search. The effect on reaction time of 60 mg caffeine can be detected, and may be evident within minutes of consumption. Objective reports of immediate beneficial effects of consumption, most research has postponed measurement to coincide with peak plasma caffeine levels (Blanchard and Sawers 1983). The intention of the present study was to investigate the effects of consuming a single cup of tea on a variety of cognitive tests. Testing began immediately after consumption and lasted approximately 80 min.