School of Psychology News & events

Research Summary

Evans, L, Wilding, E (2013 - 2014) Psychophsiological studies into task-set inertia in switching paradigms. Bial Foundation. £36,364.


In our leisure and working lives we switch between tasks multiple times every day. At home we might be preparing dinner when we have to answer a knock at the door before then resuming the original task. At work, there might be switches between writing a report, reading and answering e-mails, engagement with colleagues and so on. A robust finding is that switching between tasks results in poorer task performance, because people usually take longer to complete tasks and they are more subject to errors. These outcomes are known as switch costs. Researchers examine task switching because it indexes a crucial aspect of human behaviour; the ability to be flexible and adaptive in light of environmental demands.

One question driving the task-switching literature is: what are the processes that enable and/or hinder people in switching flexibly between thoughts and actions and, more specifically, what are the mechanisms which lead to switch costs? The research in this proposal examines one account of this – task-set inertia. According to this view switch costs reflect the interference caused by previously completing a different task, and a consequence of this is that people might still complete aspects of a previous task even when the task has changed. The experiments in this proposal build upon exciting preliminary work we have conducted using a paradigm where participants switched between a task requiring memory judgments and one that did not. Event-Related Potentials (ERPs) were collected and used to index the extent to which there was carryover of memory processing to the other task. This work successfully demonstrated that we can measure the presence of task-set inertia and also its time course, because ERP changes associated with memory were present on the non-memory task, but only on the first trial of that task.

This proposed research builds upon this initial work by examining how task characteristics and individual differences affect task-set inertia, as indexed by these ERP carry-over effects. In all the experiments described below ERPs will be acquired while people are switching between tasks to examine the influence of our manipulations on the extent of task carryover. The reason this is important is because it will provide us with an insight into why switch costs occur, and consequently a means of assisting people who have trouble with the flexible control of behaviour.

These issues will be investigated in experiments that are designed to understand the factors that influence switch costs. In three experiments we will investigate how switch costs (as indexed by ERPs) vary according to: (i) the time available to prepare for a task, (ii) the difficulty of the tasks that people must switch between, and (iii) individual differences in cognitive capacity. In combination the outcomes from these experiments will give important insights into the factors which affect task-set inertia and which might give rise to switch costs. This is important because in order for theories of switching to be 7/27 developed and refined further more information is needed about how task properties affect task execution, and crucially the mechanisms by which this occurs.

Although psychophysiological research has been applied to the study of task switching there has been no research using the sensitivity of ERPs to memory processes to measure the degree of task-set inertia and its time course. This is important because in behavioural studies only the end result of the manipulation is seen i.e. the switch cost: the means by which it yields its influence has to be inferred. The experiments proposed in this application, using ERPs, will provide a more direct measure of task-set inertia and offer novel and timely insights into how this affects the switch cost. The approach relies on the exquisite temporal precision that this psychophysiological measure offers. In total, the outcomes of this program of research will not only have implications for healthy young volunteers but also older adults and certain patient groups who are known to have difficulties in flexibly moderating their behaviour in response to external demands.