Caffeine and information processing in man

The increasing emphasis on cognitive work and mental efficiency in daily life, justifies research trying to answer the question what the effects of caffeine are on human information processing activities. Does caffeine have an influence on task performance, and more important, if so, which specific cognitive processes ar~ affected? Caffeine is generally accepted to be a mild stimulant acting on the central nervous system, producing diverse and complex effects, even when consumed in small quantities (for reviews, see Dews, 1984a; Garattini, 1993). Measures of cortical brain activity might serve as an indication of these stimulating effects. With increasing energy, the electroencephalogram (EEG) shows more activation and changes towards faster frequency and lower-amplitude activity. After caffeine a reduction in alpha and delta power has indeed been found (Kenemans and Lorist, 1995; Bruce et ai., 1986; Etevenon et ai., 1989; Newman et ai., 1992; Pollock et ai., 1981; Saletu et ai., 1987). Moreover, these studies have revealed some task-specific patterning in EEG activity (Gale and Edwards, 1983), although these measures seem less suitable to uncover more detailed effects of caffeine on cognitive processing.