The Influence of Caffeine Arousal on the Frequency of Task-Unrelated Image and Thought Intrusions

Abstract

Based upon earlier studies relating task-unrelated image and thought (TUIT) frequency to circadian activity levels and to decreases with increased age in adulthood it was hypothesized that increased cortical arousal would result in greater TUIT frequency. In a double-blind study, six young men had arousal induced at two dosages of caffeine, 100 mg and 300 mg. When unintentional and deliberate TUIT frequency at the 100 mg and 300 mg dosages was contrasted with the placebo no significant effects were noted. Change in TUIT frequency between placebo and the 300 mg dosage was significantly correlated with the personality trait of Agreeableness. Lack of compliance, caffeine withdrawal influences, and insufficiently high arousal are discussed as possible sources of the lack of relationship obtained between caffeine dosage and TUIT frequency.