The research in this thesis was motivated by the paradoxical concept of classic selfdeception; how can an individual hold two contradictory beliefs simultaneously? von Hippel and Trivers (2011) proposed that a dissociation between inaccurate explicit (conscious) and accurate implicit (unconscious) information may facilitate self-deception. The thesis aims were to provide support for the dissociation theory, and to explore whether either system was predictive of future decision-making. This was examined via perceptions of control using tasks, in which responses and outcomes were predominantly noncontingently related (Alloy & Abramson, 1979). It was hypothesised that people would treat noncontingent situations as contingent situations and display illusions of control (IOC). In line with the theory of depressive realism, it was proposed that nondepressed people would report greater IOCs, whilst depressed people would be more realistic (Dobson & Franche, 1989). The task enabled the comparison between the subjective explicit/implicit judgements of control and the objective control. The novelty of the analysis was that the implicit measure of control was calculated using the judgements of reinforcement for each response. The results demonstrated strong evidence for the IOC, as the explicit perceptions were greatly overestimated compared to the actual control experienced. Conversely, the implicit judgements were more similar to the actual control, and thus more accurate. Therefore, support for the dissociation theory was present. However, contrary to expectations, subsequent response decisions appeared to be predominantly influenced by the more accurate implicit system. Additionally, there was only weak support for the depressive realism theory. This research has important implications for the adaptiveness of self-deception, how it can function within an individual, and the notion that mentally healthy people perceive reality accurately. Indeed, the prevalence of the IOC throughout the experiments indicates that people are commonly prone to unrealistically positive illusions, which has applications for clinical therapy.