Switching between simple cognitive tasks: The interaction of top-down and bottom-up factors

How do top-down factors (e.g., task expectancy) and bottom-up factors (e.g. , task recency) interact to produce an overall level of task readiness? Thi s question was addressed by factorially manipulating task expectancy and ta sk repetition in a task-switching paradigm. The effects of expectancy and r epetition on response time tended to interact underadditively, but only bec ause the traditional binary task-repetition variable lumps together all swi tch trials, ignoring variation in task tag. When the task-recency variable was scaled continuously, all 4 experiments instead showed additivity betwee n expectancy and recency. The results indicated that expectancy and recency influence different stages of mental processing. One specific possibility (the configuration-execution model) is that task expectancy affects the tim e required to configure upcoming central operations, whereas task recency a ffects the time required to actually execute those central operations.