Preparation, interference and task switching: using distributional analysis and cognitive modelling estimates to extend the FTE theory

For more than two decades, the processes involved in task switching have been extensively investigated and numerous theories proposed attempting to explain task switch phenomena, such as switch costs, preparation effects and residual switch costs (Grange & Houghton, 2014b). A range of experimental paradigms have been employed to demonstrate the key factors that influence performance; from endogenous mechanisms related to cognitive control and executive functioning, through to task priming, interference and decay processes. I begin this thesis by providing an overview of significant task switch theories, paradigms and findings to illustrate the breadth of existing task switch research. Following this, I present a series of experiments that employ distributional analysis to investigate anticipatory preparation and proactive interference effects on task switch performance. The experiments lead to the proposal of a descriptive, activation driven model of performance, which is tested using specific experimental manipulations. The results indicate the importance of design parameters and how these can affect responding based on strategic and structural task switch related processes. Finally, I investigate the Failure to Engage (FTE) account of residual switch costs (De Jong, 2000) and replicate research that challenges this theory (Brown, Lehmann & Poboka, 2006). The results guided an extension of FTE that was tested in a further experiment and shown to be able to accommodate the effects of interval manipulations as well as both task and cue switching. I then apply a new modelling approach to obtain direct estimates of the probability of preparation and conclude that De Jong’s insights about preparation failure provide a tractable framework for understanding many aspects of cognitive control, including explaining aspects of all of the four major task-switching phenomena identified by Monsell (2003).