The biopsychosocial model (BPSM) offers a potential explanation for why individuals perform differently in pressurised motivated performance situations (e.g., sporting competitions). The aim of this thesis was to test the predictions of the BPSM to further our understanding of performance variability under pressure. Specifically, the BPSM suggests that individuals’ respond to a pressurised situation with either a challenge or threat state, with the former resulting in better performance. Three experimental studies were conducted to test this proposition and examine the immediate effect of challenge and threat states on the performance of laboratory-based motor tasks and real competition. Across all studies, a challenge state resulted in, or was associated with, superior performance. Importantly, this finding was consistent across different samples and research designs. In two of these studies, the proposed mechanisms (emotional, attentional, and behavioural) through which challenge and threat states might influence performance were also investigated. In both studies, a challenge state was associated with more favourable emotions (less anxiety and more facilitative interpretations) and attention (longer quiet eye durations and less conscious processing). Furthermore, in one study, a challenge state was also associated with more effective behaviour (lower muscle activity and superior clubhead movements). Crucially, mediation analyses indicated that challenge and threat states influenced performance by impacting the quality of task-related movements. The BPSM predicts that a range of factors influence whether an individual responds to a pressurised situation with a challenge or threat state (psychological and physical danger, familiarity, uncertainty, required effort, skills, knowledge and abilities, and the availability of support). In a fourth experimental study, two of these antecedents were examined; perceived required effort and support availability. In this study, although perceptions of support availability had limited impact, perceptions of low required effort led to a challenge state and better performance than perceptions of high required effort
