Single-System and Dual-Process Accounts of Explicit and Implicit Memory

While some expressions of memory are accompanied by conscious awareness, others do not elicit this awareness yet still impact task performance. Theorists have long questioned whether these explicit and implicit forms of memory are governed by separate cognitive systems or a single system. There is much behavioural evidence for multiple-systems and dual-process accounts, mainly focusing on studies of recognition memory and long-term repetition priming. However, experimental results and mathematical modelling have shown the ability of a single-system account to explain the relationship between various forms of explicit and implicit memory. This thesis uses behavioural experiments and mathematical modelling to further investigate the predictions of single-system and dual-process accounts of explicit and implicit memory. Chapter 2 investigates the effect of response speeding in recognition and priming tasks, identifying model-based predictions prompted by this manipulation. Chapter 3 examines the effects of encoding variability on recognition memory, before extending this manipulation to priming to again investigate opposing predictions from single-system and dual-process models. Chapter 4 takes a different approach and investigates the relationship between cued recall and implicit memory in behavioural experiments, with and without the inclusion of a recognition task. Finally, Chapter 5 examines the relationship between free recall and implicit memory in three further experiments. The results of this thesis show that while models of recognition and priming make opposing predictions about the relationship between explicit and implicit memory, these predictions are often hard to test in practice. However, Chapter 4 confirms the relationship between cued recall and priming. Chapter 5 provides evidence for a similar relationship between free recall and priming. Both of these results align with a single-system view over a strict dual-process (and strict multiple-systems) account. With further experimentation, these results may inform future model development and the understanding of the fundamental relationships between explicit and implicit memory