Mental Fatigue: Examining Cognitive Performance and Driving Behavior in Young Adults

Mental fatigue causes an increase in task-based EEG theta and alpha power and a decrease in performance (for a review, see Tran et al., 2020). However, little is known about the emergence of mental fatigue in resting state EEG recordings and whether the progression of mental fatigue over time is influenced by individual differences. The current dissertation examined the utility of resting state EEG as a measure of mental fatigue by testing whether EEG power changed in young adults over the course of a cognitively demanding battery of tasks. The current dissertation also tested how this measure of mental fatigue interacted with individual differences in ADHD symptomology to predict performance on one of the cognitive tasks as well as performance in a driving simulator. Resting state EEG was recorded at four intervals, before and after the three cognitively demanding tasks. Driving outcomes were collected at a separate visit to a driving simulator lab. Results indicated that resting state EEG theta and alpha power significantly decreased over time, but this association was not influenced by levels of ADHD symptomology. There was no evidence that resting state EEG power changes over time predicted cognitive or driving performance, even when ADHD symptomology was included. The current findings present preliminary evidence that resting state EEG power can be used as a marker of mental fatigue and provide unique insight into how mental fatigue develops by including an initial measurement of neural readiness before individuals engage in a cognitively demanding task

Death, Hope and Sex Revisited: An Evaluation of Psychosocial Acceleration Theory

Psychosocial Acceleration Theory (Belsky, Steinberg & Draper, 1991; Chisholm, 1993; 1999a) is an explanatory framework that recasts behaviours viewed as deviant or pathological (such as aggression and early reproductive behaviour) as adaptive strategies for individuals developing in high stress environments. Chisholm and later theorists linked disrupted attachment process during early childhood to perceptions of an uncertain future and local mortality rates. Uncertain futures cause individuals to focus on present consumption (shortening “time preference”) to avoid lineage extinction through accelerated reproductive function and competitive behaviours. Questions remain as to the details of how this process operates; specifically, the identification of environmental stressors, the specification of Chisholm’s “time preference” mechanism and the role of biological sex. This thesis evaluated psychosocial acceleration theory by exploring these questions. The combined empirical evidence from seven studies (using primary and secondary data) generally supports and extends psychosocial acceleration theory as a framework for explaining how and why various behaviours cluster together in predictable ways and how these life history trajectories represent alternative, conditional strategies shaped by environmental experiences. Evidence suggests that sex-ratio, population density, socioeconomic stress, low education and shorter life expectancies represent distinct sources of stress that promote greater family instability, which in turn, increases aggression, crime, teenage pregnancies and reproductive development. However data also suggest (somewhat contrary to Chisholm) that these same environmental factors can act independently of family instability. Psychological traits (particularly sensation seeking and impulsivity) that meet key predictions derived from Chisholm’s work are discussed as mediating mechanisms representative of “time preference” linking perception of ecological stress with behaviour. The role of biological sex, whilst in line with many evolutionary derived predictions, demonstrates distinct pathways for males and females. Future work and limitations are discussed in commentaries throughout in relation to pertinent evolutionary literature