This thesis investigates potential psychological mechanisms that influence motor performance in sport, including colour, inhibition function, and propensity for conscious control of movement. A question was raised about whether individuals with poor inhibition function would be more likely to have a high propensity for conscious control (i.e., reinvestment) because they are less able to inhibit conscious control. However, Experiment 1 (Chapter 2) and Experiment 2 (Chapter 3) revealed a positive association between inhibition function (indexed by the Go/NoGo task) and propensity for conscious control of movement (assessed by the Movement Specific Reinvestment Scale, MSRS). Experiment 3 (Chapter 4) examined the effect of colour on inhibition function during a basketball-specific Go/NoGo task. Worse inhibition performance was evident when participants viewed an opponent in a green uniform compared to a red and a grey uniform, possibly because green conveys the meaning to ‘go’ (e.g., at traffic lights). Archival data of professional netball games was analysed to examine whether teams in green uniforms made more intercepts because green lowers an opponent’s ability to inhibit an ill-chosen pass. Findings revealed higher mean intercepts for teams wearing green uniforms than for teams wearing red and other-coloured uniforms. Experiment 4 (Chapter 5) examined whether the effect of uniform colour may be due to differences in an opponent’s perception of size. A side-by-side comparison task revealed that goalkeepers in a red and a blue uniform were perceived as larger than goalkeepers in a green uniform, possibly because red and blue colours convey the meaning of dominance and threat in a football context (e.g., the most successful teams, like Manchester United and Chelsea, wear red and blue colours). Experiment 5 (Chapter 6) examined whether viewing a red and a blue spectator background would elicit avoidance motivation during football penalty-kicks, because they conveyed the meaning of dominance and threat. Professional football players displayed avoidance motivation (i.e., choosing the easier option/ kicking towards the larger side of the goal) when viewing a red and a blue spectator background compared to other-coloured backgrounds. Based on Experiments 4 and 5, it was argued that viewing a red and a blue spectator background elicited avoidance motivation because red and blue convey the meaning of dominance and threat in football. In Experiment 6 (Chapter 7), retrospective analysis of professional football games was conducted to examine whether avoidance motivation would also be evident when facing a hostile crowd (a threatening stimulus). Consistently, penalty-kickers chose the easier option/ kicked to the larger side of the goal (i.e., avoidance motivation) more often when facing a hostile crowd rather than a supportive crowd. It was suggested that viewing a threatening stimulus (1) increases arousal levels, which exacerbates the negative emotions that are experienced by kickers during penalty-kicks in real-life or (2) viewing a threatening stimulus aids visual discrimination of available space, allowing kickers to identify and kick towards the larger side more often. The findings of this thesis revealed a positive association between inhibition function and movement specific reinvestment propensity, which suggests that ability to inhibit inappropriate motor responses may be a function of inter-personal differences in the propensity for conscious control of movements. Support was found for the effect of colour in sporting contexts. Overall, the findings suggest that the colour effect only occurs if the colour-meaning association reaches an adequate salience threshold within a specific context. In addition, it was argued that while context influences emotional valence (positive, negative emotions), colour influences arousal, which exacerbates the level of negative emotion. An attempt is made to integrate the findings from the thesis with previous evidence to begin development of a theoretical framework for the effects of colour on human performance.