One Coffee is Just a Snack. No effect of a low dose of caffeine on the objective and declarative functioning of the individual.

Studies on the effects of coffee in recent years have yielded ambiguous conclusions. We believe that the reason lies in incompatible research methodologies. In this paper, we draw attention in the research plans to a) unrealistically high doses of caffeine used in the studies; b) the distinction between objective and subjective effects; and c) the interaction with psychological factors. In the conducted study ( N = 150) in the 2x2 design (controlled daily coffee drinking x coffee vs. placebo), we show that caffeine, in the form of a realistic dose of one coffee, has no significant effect on the subjective and objective abilities of the participants. We therefore want to increase interest in the area to results showing no effects and inconsistent with current beliefs about the action of this (apparent) stimulant.