Abstract

CAFFEINE, SEMANTIC PROCESSING, LOGICAL REASONING, IMPLICIT MEMORY, RECOGNITION MEMORY AND ALLOCATION OF MEMORY RESOURCES

Dominic P. Nguyen-Van-Tam, PhD and *Andrew P. Smith, PhD

Abstract

Background: Research has shown that caffeine improves the performance of semantic processing and logical reasoning tasks. The present study aimed to confirm the positive effects of caffeine on these tasks and to investigate other aspects of memory, namely implicit memory, recognition memory and allocation of memory resources. Methods: Participants (University students, N=48) completed two laboratory sessions on consecutive days. Separate groups either received caffeine or a placebo on each day or had a different condition on each day. The caffeine dose was 4mg/kg and was carried out double-blind. On day one, the participants carried out memory tests investigating semantic processing, logical reasoning, immediate recall and recognition, implicit memory and allocation of memory resources. On day two, delayed recall and recognition were tested, and a word fragmentation completion task was carried out. Results: The performance of the semantic processing and logical reasoning tasks was significantly better in the caffeine condition, as were implicit memory and word fragmentation completion. Caffeine also led to resources being directed away from lowpriority task components. Caffeine had no significant effect on immediate recall or recognition. On day two, delayed recall and recognition were not influenced by caffeine. Conclusion: The results from this study confirm the effects of caffeine on semantic processing and executive function. Recall and recognition were not influenced by caffeine, but there were new effects on the implicit memory and allocation of memory resources tasks. These results extend our knowledge of caffeine and memory and show that semantic processing and logical reasoning tasks can be used as positive controls in future research on this topic.

Keywords: Caffeine; Semantic processing; Executive function; Immediate and delayed recall and recognition; implicit memory; Allocation of memory resources.