The effects of caffeine on visual selective attention to color: An ERP study

Event-related potentials were recorded from 11 subjects after ingesting caf feine (250 mg) or placebo. Subjects were instructed to attend selectively t o stimuli with a specified color (red or blue) in order to react to the occ urrence of a target within the attended category. Reaction times revealed f aster responses for the caffeine condition, whereas no differences in strat egy were observed. Color attention effects were identified as frontal selec tion positivity, occipital selection negativity, and N2b, whereas target de tection was reflected in P3b. Effects of treatment were found as a more pos itive-going frontal P2 component in the caffeine condition. In addition, an interaction between attention and treatment could be observed on the N2b c omponent. This pattern of results suggests that caffeine yields a higher ov erall arousal level, more profound processing of both attended and unattend ed information. and an acceleration of motor processes.