Caffeine boosts preparatory attention to reward-related information

Both the intake of caffeine-containing substances and the prospect of rewards have been associated with improved behavioral performance. These improvements might be related to an effect on attentional preparatory mechanisms, potentially through the influence of both caffeine and the prospect of rewards on the dopaminergic system. To examine the common influence of caffeine and reward on preparatory attention, we tested twenty-four participants during a two-session experiment in which they performed a cued-reward Stroop task. At the start of each trial, participants were presented with a cue to inform them whether they had to prepare for presentation of a Stroop stimulus and if they would receive a reward based on their performance. During each session, participants received either coffee with caffeine (3 mg/kg) or with lactose (placebo). In addition to behavioral measures, the electroencephalography (EEG) was recorded. Results showed that both the intake of caffeine, as w! ell as the prospect of reward improved speed and accuracy. However, the effects of caffeine and reward-prospect did not interact on the performance level. Furthermore, the prospect of rewards resulted in enlarged contingent negative variation (CNV), which has been shown to be related to enhanced preparatory attention. Interestingly, the reward-related CNV enhancement was more pronounced in the caffeine condition as compared with the placebo condition. These results revealed that caffeine intake boosts preparatory attention for task-relevant information that can lead to reward.