Daily and Non-daily Smokers: A Profile of Drive and Cognitive Control Mechanisms

Historically, smokers were considered a single homogeneous group, but over the past two decades research has increasingly focused on differentiating daily and non-daily smokers. Despite fundamentally different smoking habits and motives, daily and non-daily smokers have similar cessation rates. In order to understand why both groups may experience a similar difficulty quitting smoking, this thesis explored neurocognitive mechanisms associated with addictive behaviour. In order to profile these mechanisms, a systematic review was conducted, highlighting there was a gap to address in two areas of research relating to drive and control. Study One (N = 60) and Study Two (N = 166) investigated attentional bias towards smoking cues using the visual probe task, finding there was no meaningful difference between daily and non-daily smokers in trait-level attentional bias. Study Three (N = 28) measured ERP components associated with inhibitory control (Go/NoGo task) and error processing (Eriksen Flanker task). There were no significant effects of interest, but the sample size was smaller than planned. This thesis made three contributions to the study of addictive behaviour. First, the systematic review highlighted that research investigating lighter and heavier smokers has a problematic level of heterogeneity in the definitions used to define the groups. Second, there was no meaningful difference in attentional bias between daily and non-daily smokers, supporting contemporary theories that attentional bias may be best conceptualised as a state-level construct. Finally, internal consistency estimates of the ERP measures of inhibitory control and error processing supported previous research reporting good psychometric properties. Overall, this thesis presented a focused profile of measures relating to drive and control neurocognitive mechanisms, but there were no meaningful differences between daily and non-daily smokers. If these mechanisms are important to addictive behaviour, future research will have to investigate their role using alternative designs.

The comparisons of inhibitory control and post-error behaviors between different types of athletes and physically inactive adults

To properly behave and correct mistakes, individuals must inhibit inappropriate actions and detect errors for future behavioral adjustment. Increasing evidence has demonstrated that athletes are superior in cognitive functions and this benefit varied dependent on the types of sport that individuals involved in, but less is known on whether athletes have a different error-related behavioral pattern. The purpose of this study was to compare the behavioral performance of inhibition and error monitoring between individuals who participated in an open-skill sport (n = 12), a closed-skill sport (n = 12), and a sedentary lifestyle (n = 16). A combined flanker/stop signal task was presented and the derived stop signal reaction time (SSRT), post-correct accuracy and reaction time (RT), as well as post-error accuracy and RT were compared across groups. Our findings indicated there was no difference in SSRT between groups. Surprisingly, significant post-error slowing (PES) was observed only in controls but not in sport groups, the controls also exhibited significantly longer post-error RT compared with the open-skill group. However, there was no difference in the post-error accuracy between groups, indicating a higher efficiency in the post-error processing among open- and closed-skill groups by requiring comparatively less time for behavioral adjustments. The present study is the first to disclose the discrepancies in PES between different types of athletes and controls. The findings suggest that sport training along with higher amounts of physical activity is associated with a more efficient behavioral pattern for error processing especially when the sport requires open skills in nature.