STUDY ABSTRACT: This study examined whether preparation and performance can affect our upcoming behaviour in different ways, by examining different types of switch cost following trials that were only prepared (cue-only) or both prepared and performed (completed). In a double-registration cued task-switching procedure, participants responded to the task cue as they prepared the cued task, and to the target as they performed that task, to give switch costs at both cue (preparation) and target (performance). Cue-only trials included only a cue but no target; completed trials included both a cue and a target, and the effects of these two types of trial were assessed at cue and target responses on the following (completed) trial. Two cues were used for each task, so two types of switch cost could be calculated: the cue-switching cost (i.e., switching versus repeating cues when completing the same task) and the task-switching cost (i.e., switching versus repeating tasks, with cues switching in both cases). A different pattern of switch costs being present following completed trials than was present following cue-only trials would indicate that that preparation and performance have differing types of effect on our subsequent behaviour.GRANT ABSTRACT: In this project we will investigate whether what we "know" and what we "do" have different effects on our subsequent behaviour. We will do this by looking at our ability to switch between different tasks. Specifically, we will compare how difficult it is to switch away from a task that we have either: a) only prepared to perform (we "knew" what the relevant task was but we didn't "do" it), or ii) actually performed (we both "knew" it and "did" it). In our everyday lives we frequently need to switch between the different rules that guide our behaviour. For instance, when driving a car we might switch rapidly between the following "tasks": visually assessing potential hazards at a junction; accelerating past a tractor; performing an emergency stop. From studies using laboratory tasks, we know that switching tasks usually leads to slowed responses, and that we occasionally even repeat the previous task in error. The existence of this "switch cost" reveals that some aspect of the previous task must persist in some way to affect the speed or accuracy of our subsequent behaviour, even though we know that it is no longer relevant. In this project, we wish to find out about what causes this cost of switching between tasks. Our main question concerns whether just preparing a task ("knowing") will have different consequences from actually performing it ("doing"). There are various examples in psychology of situations where what we know has surprisingly little impact upon what we do. For instance, we can sometimes verbally repeat instructions given to us, and demonstrate that we understand and remember them, but then fail to implement them at all (a phenomenon known as "goal neglect"). A similar distinction has been drawn in task-switching research. It had been thought that doing a task would produce a subsequent switch cost, but that knowing which task should be performed without actually carrying it out would produce no subsequent cost. However, more recent evidence using a different method suggests that merely preparing a task can in fact produce a substantial switch cost, even if the prepared task was not performed. We will conduct a series of psychological experiments in which people perform two different tasks. For instance, we will show them coloured shapes (like a blue circle) and ask them to press a button to indicate either what the colour is or what the shape is. By intermixing the two tasks randomly, we will be able to assess people's ability to switch between tasks, relative to repeating tasks - that is, we can measure each person's switch cost. On most trials, people will prepare a task and then perform it: for instance, they may see the word "colour" and then a blue circle, at which point they press the appropriate button to indicate that the colour is blue. Crucially, however, on some trials we will require a task to be prepared but not performed: e.g., we may show the word "colour" but then no coloured shape, instead moving straight on to the next trial. Therefore, we will be able to measure the switch cost that follows preparation separately from the switch cost that follows performance. Across a series of experiments we aim to find out what causes these types of switch cost to be established and abolished, and in what ways the switch cost driven by preparation may differ from that driven by performance. The cost of switching tasks indicates a fundamental limitation in our cognitive system that is relevant to many situations (e.g., working in a busy office, driving in heavy traffic, preparing dinner while taking care of a baby). Understanding the mechanisms behind this limitation is of potential practical importance with respect to reducing risks associated with this cost. The present project will meet this challenge by illuminating the origin of this limitation.

Participants (primarily undergraduate and postgraduate students) completed a 35-45 min computerised experiment using E-Prime 2.0 which was based on Arrington, Logan, and Schneider’s (2007) dual-registration paradigm but which also included cue-only trials (based on Lenartowicz, Yeung, & Cohen, 2011). Participants were instructed that they would be switching between two tasks: a colour-judgement task and a shape-judgement task. They were informed about which task they should do on every trial by a cue that was presented for 200ms; this was followed by a blank screen. Participants then had to press one of two buttons (with their left hand) to confirm which task they were to perform. On 70% of trials (the “completed” trials), 100ms after they responded to the cue participants were presented with a target (a coloured shape) for 200ms. This was followed with a blank screen until participants responded by pressing one of two buttons (with their right hand) to perform the cued task. There was then a 100ms blank screen until the next trial started. On the remaining 30% of trials (the “cue-only” trials), 100ms after participants responded to the cue the next trial started. There were two cues per task (these were words: COLOUR and HUE for colour-judgement, SHAPE and FORM for shape-judgement). There were four target features per task (red, green, blue, yellow; square, circle, triangle, diamond). Participants responded to both cues and targets using a Cedrus button box and the reaction time and accuracy of responses were measured.