EFFECTS OF CAFFEINE AND GENDER ON PHYSIOLOGY AND PERFORMANCE - FURTHER TESTS OF A BIOBEHAVIORAL MODEL

The present study extended testing of our biobehavioral model describi ng the effects of arousal and caffeine to include an examination of ge nder differences and their interactions with habitual and acute caffei ne ingestion. Males and females selected as high or low habitual caffe ine users were randomly assigned to receive either caffeine or a place bo and exposed to novel and repetitive recall tasks and to simple audi tory stimuli. Electrodermal activity and recall task performance were recorded. The four major factors examined, including habitual caffeine use, acute ingestion, gender, and stimulus novelty, affected behavior , physiology, or both. Results showed that habitual caffeine usage sys tematically affected tonic arousal (skin conductance level) and improv ed recall task performance. Acute caffeine ingestion increased phasic arousal (skin conductance response amplitude) and reduced habituation rates. Gender interacted with other factors to significantly affect bo th tonic and phasic arousal, and females performed better than males o n the recall tasks. These results were partially supportive of the the oretical model, and further work is needed to examine the interactions of acute and chronic caffeine intake with gender and novelty.