"Caffeine is known to increase arousal, attention, and information processing—all factors implicated in facilitating persuasion." In other words, coffee makes you more open to persuasion. And, it turns out that only strong arguments are more persuasive under the influence of caffeine. Apparently, it opens your mind and helps one judge the strength of a good argument. So, next time your selling to a client or arguing with your spouse, insist they have a cup coffee beforehand.