Lorist M M, Snel J, Kok A
Department of Psychonomics, University of Amsterdam, The Netherlands.
Psychopharmacology (Berl). 1994 Jan;113(3-4):411-21. doi: 10.1007/BF02245217.
The effects of caffeine on different information processing stages were examined by using choice reaction time tasks. Independent variables were stimulus degradation, stimulus-response compatibility, time-uncertainty, state of the subject, and caffeine treatment. The task variables were assumed to affect the following processing stages; encoding, response selection and motor preparation, respectively. A 200 mg dose at the beginning of the experiment and a maintenance dose of 50 mg caffeine or lactose half-way through the session were administered to well rested and fatigued subjects, double-blind and deceptively. Behavioural measurements, event-related potentials (ERPs) and mood questionnaires were used to assess caffeine effects. The data showed that caffeine shortened reaction time. This effect showed an interaction with stimulus degradation and time uncertainty. In addition, ERP results supported the view that caffeine increases cortical arousal and perceptual sensitivity. Stimulating effects of caffeine were mainly located at input and output stages of the information processing system. Central processes were unaffected by caffeine. Fatigued subjects showed larger improvements in performance after caffeine than well-rested subjects. The results also indicated that caffeine effects were not stimulating in all subjects: 6 out of 30 subjects did not show arousing effects of caffeine.
通过使用选择反应时任务来研究咖啡因对不同信息处理阶段的影响。自变量包括刺激退化、刺激-反应相容性、时间不确定性、受试者状态以及咖啡因处理。任务变量被认为分别影响以下处理阶段：编码、反应选择和运动准备。在实验开始时给予200毫克剂量，在实验过程中间给予50毫克咖啡因或乳糖的维持剂量，对休息良好和疲劳的受试者进行双盲和欺骗性给药。使用行为测量、事件相关电位（ERP）和情绪问卷来评估咖啡因的效果。数据表明咖啡因缩短了反应时间。这种效应表现出与刺激退化和时间不确定性的相互作用。此外，ERP结果支持了咖啡因增加皮层唤醒和感知敏感性的观点。咖啡因的刺激作用主要位于信息处理系统的输入和输出阶段。中枢过程不受咖啡因影响。与休息良好的受试者相比，疲劳的受试者在摄入咖啡因后表现出更大的性能改善。结果还表明，咖啡因对所有受试者并非都有刺激作用：30名受试者中有6名未表现出咖啡因的唤醒作用。
