Task complexity affects exogenous but not endogenous components of switch cost

A review of 29 papers from the task switching literature reveals no relationship between the time taken to repeat a task and the additional time taken when switching between tasks (switch cost). A visual discrimination task and a schematic judgement task differing in complexity according to a principled model of cognition show that the endogenous component of switch cost was not affected by the difference in task complexity, but the exogenous component was, even when repeat task completion time was taken into account. The endogenous component is interpreted as a constant overhead related to the time taken to retrieve task schemata, while the exogenous component is related to the number of processing components involved in a task.