Perfectionism entails a salient cognitive component characterised by a ruminative response to imperfection. However, research examining the influence of this cognitive component in sport is limited. The broad aim of this thesis was therefore to extend previous research in perfectionism by examining the relationships between perfectionism, overthinking (e.g., perfectionistic cognitions) and emotions in the context of football. To achieve this aim, four empirical studies were conducted. The first study adopted a cross-sectional, survey-based design and found that perfectionistic cognitions predicted negative pre-competition emotions (anxiety, anger, and dejection) when controlling for self-oriented perfectionism (SOP) and socially prescribed perfectionism (SPP). The second study adopted a longitudinal, survey-based design and found that, at between-person level, perfectionistic cognitions were a mechanism by which SOP and SPP were significantly and positively related to pre-competition emotions (anxiety, dejection, excitement, anger, and happiness) and dimensions of anxiety (cognitive and somatic) and anger (feel anger, verbal anger, and physical anger). Also, at within-person level, SOP (but not SPP) predicted changes in perfectionistic cognitions, which in turn predicted changes in pre-competition anxiety, excitement, and anger, and dimensions of anxiety and anger. The third study adopted a mixed-methods approach to identify perfectionistic footballers and interview them about their psychological experiences pre-, during-, and post-performance. Perfectionistic footballers described experiencing a range of cognitions and emotions during the course of their performances. Because the three studies provided evidence that perfectionistic cognitions are likely to impact the emotional experiences of footballers, the fourth study examined the effectiveness of a self-help intervention in reducing perfectionism, perfectionistic cognitions, and negative pre-competition emotions. The findings demonstrated that SPP, perfectionistic cognitions, anxiety, anger, and dejection significantly reduced because of the intervention. Collectively, the thesis supports the notion that the cognitive component of perfectionism is important in contributing to negative pre-competition emotions for footballers.
