Switch Cost

Switch cost refers to the measurable decline in speed, accuracy, or both, that occurs when a person switches from performing one task or mental rule to performing a different one, compared with their performance when simply repeating the same task on consecutive trials. Researchers study the effect using task-switching paradigms in which participants alternate, in a controlled sequence, between two or more simple tasks, such as classifying a number as odd or even versus classifying it as high or low, finding consistently that switch trials produce slower and often less accurate responses than repeat trials even when the two tasks are individually simple and well practiced. Influential work on task switching from researchers including Stephen Monsell in the 1990s helped establish that this cost persists to some degree even when a person has substantial advance warning of an upcoming switch and time to prepare for it, a residual component that has been particularly important for theorizing about the underlying mechanism, since it suggests the cost cannot be entirely eliminated simply through deliberate advance preparation. Switch cost is widely used as a laboratory measure of cognitive flexibility and executive control, the broader set of mental processes responsible for flexibly reconfiguring goals, rules, and attention when task demands change.