EFFECTS OF CHEWING GUM AND CAFFEINE CONSUMPTION ON THE PERFORMANCE OF FOCUSED ATTENTION AND CATEGORIC SEARCH CHOICE REACTION TIME TASKS

*Andrew P. Smith, PhD

ABSTRACT

Background: There has been extensive research on caffeine and behaviour, and most studies have considered the effects of acute ingestion rather than regular consumption. The same applies to research on chewing gum. The aim of the present research was to examine associations between the level of caffeine consumption, chewing gum, and performance of focused attention and categoric search choice reaction time tasks. The effects of age and time of testing were also investigated. Method: Two hundred and seventy students and staff (159 females, 113 males; mean age 35.4 years, age range 17-65 years) from Cardiff University participated in the research. They completed the tasks between either 11.00-13.00 or 16.00-18.00. Participants carried out focused attention and categoric search two-choice reaction time tasks. They also completed psychosocial questionnaires to determine whether caffeine and chewing gum were associated with these measures. Results: Chewing gum and level of caffeine consumption did not have significant effects on the psychosocial measures. Chewing gum was associated with faster reaction times on both tasks. Caffeine was associated with a speed error trade-off, with high consumers responding more slowly but more accurately. Those who chewed gum were younger than the non-chewers, and high-caffeine consumers were older than low consumers. Older participants responded more slowly but more accurately, and responses were faster later in the day. The effects of chewing gum and level of caffeine consumption were no longer significant when age and time of day were included in the analyses. Conclusion: Gum chewing and level of caffeine consumption were not significantly associated with psychosocial measures. Chewing gum was associated with faster response times and high caffeine consumers responded more slowly but more accurately than low consumers. Both the effects of chewing gum and the level of consumption of caffeine could be accounted for by age differences in the groups. This demonstrates the importance of controlling for age and time of testing in studies using these choice reaction time tasks.

Keywords: Age; Gender; Time of day; Chewing gum; Caffeine; Focused attention; Categoric search; Choice reaction time; Errors; Lapses of attention.