Caffeine enhances real-world language processing: evidence from a proofreading task

Caffeine has become the most prevalently consumed psychostimulant in the world, but its influences on daily real-world functioning are relatively unknown. The present work investigated the effects of caffeine (0 mg, 100 mg, 200 mg, 400 mg) on a commonplace language task that required readers to identify and correct 4 error types in extended discourse: simple local errors (misspelling 1- to 2-syllable words), complex local errors (misspelling 3- to 5-syllable words), simple global errors (incorrect homophones), and complex global errors (incorrect subject-verb agreement and verb tense). In 2 placebo-controlled, double-blind studies using repeated-measures designs, we found higher detection and repair rates for complex global errors, asymptoting at 200 mg in low consumers (Experiment 1) and peaking at 400 mg in high consumers (Experiment 2). In both cases, covariate analyses demonstrated that arousal state mediated the relationship between caffeine consumption and the detection and repair of complex global errors. Detection and repair rates for the other 3 error types were not affected by caffeine consumption. Taken together, we demonstrate that caffeine has differential effects on error detection and repair as a function of dose and error type, and this relationship is closely tied to caffeine's effects on subjective arousal state. These results support the notion that central nervous system stimulants may enhance global processing of language-based materials and suggest that such effects may originate in caffeine-related right hemisphere brain processes. Implications for understanding the relationships between caffeine consumption and real-world cognitive functioning are discussed.     

Attention Problems Mediate the Association between Severity of Physical Abuse and Aggressive Behavior in a Sample of Maltreated Early Adolescents

Empirical evidence has accumulated documenting an association between childhood physical abuse and aggressive behavior. Relatively fewer studies have explored possible mediating mechanisms that may explain this association. The purpose of the current study was to examine whether caregiver- and youth-reported attention problems mediate the association between physical abuse severity and aggressive behavior. A sample of 240 maltreated early adolescents (ages 9-11) and their caregivers were interviewed within 14 months of being removed from the home. Results from multiple regression analyses indicated that caregiver- and youth-reported attention problems were partial mediators of the association between physical abuse severity and aggressive behavior. These associations were significant even after controlling for children's intellectual functioning, sex, age, and severity of other maltreatment types. Possible explanations for the detrimental impact of physical abuse on behavior are discussed, along with the implications of the current study's results for interventions aimed at reducing early adolescent aggressive behavior.