Sequential effects in simple decision making: testing proposed mechanisms and identifying candidate processes for individual differences

Sequential effects have emerged as a ubiquitous facet of choice-reaction time experiments, and refer to the systematic variation in reaction time and accuracy as a function of the preceding trial sequence. The aim of this thesis is to contribute to the resolution of some ambiguities in the sequential effects literature, and expand our understanding of sequential effects by examining how they manifest in previously unexplored tasks, and different experimental conditions. The specific questions that will be addressed in this thesis relate to (1) the persistence of the influence of previous trials, given a recent account that sequential effects may be long-lasting, contrary to previous evidence suggesting that they are transient in nature, (2) delineating the impact of difficulty manipulations on the relative influence of the mechanisms of sequential effects,(3)examining how sequential effects manifest in a novel task that has been shown to generate unique effects of sequence, and that may share common underlying mechanisms, and (4) identification of candidate processes for further research into individual differences in the manifestation of these effects. The first question will be addressed in chapter 2, which consists of a replication, reanalysis, and test of a model that has suggested that sequential effects may persist for much longer than previously thought. Chapter 3 will investigate the relative influence of the underlying mechanisms of sequential effects, which have been previously difficult to delineate, partly due to the nature of the experimental manipulations used. Lastly, questions 3 and 4 will be addressed in chapter 4, which aims to extend the study of sequential effects in new experimental paradigms, and in doing so, illuminate the relationship between different effects of sequence, and identify candidate processes for the investigation of individual differences.