This study addresses the influence of energy drinks on concentration, examining in particular the impact of their stimulating ingredients (physiological effect) and product label (label/placebo effect) on objectively measured and perceived concentration.

A 3 x 3 (beverage x product label) – cross-factorial between-subjects design was applied. 364 students sampled a beverage, evaluated their perceived concentration at different points in time and completed a standardized concentration test after a latency of 30 minutes. While the beverage itself had neither an effect on perceived concentration nor on the concentration test results, perceived concentration was influenced by the product label.

The relation between the product label and perceived concentration was partly mediated by expectations, which in turn were conditionally moderated by the global belief in the efficacy of energy drinks.