Effect Of Prepare Levels On Task Switch

While cognitive psychology has made substantial progress in recent years in analyzing particular cognitive processes, much less progress has been made with regard to the mechanisms that guide or control theses processes. Task switching as an important paradigm in the study of control mechanisms provides a possible method for investigating some aspects of these controls. Source of switch cost is a key issue in the study of task switching. Progress in disentangling the complex causation of switch cost is necessary to interpret the effects of ageing, behaviors of brain damage and individual differences in task switching.Myeong-Ho Sohn and John R Anderson think task preparation can be achieved by giving people foreknowledge that they will perform a special task: its effects reflect endogenous executive control. They investigate the prepare effects with foreknowledge and with no foreknowledge. But their study only investigates the difference between with foreknowledge and with no foreknowledge and mainly focuses the executive control but not automatic control of the upcoming task.We manipulate foreknowledge about the upcoming task to control participants' prepare levels and examine the roles of executive control and automatic control in task switching. In our study, foreknowledge about the upcoming task includes the task type information and stimulus location information. In task type foreknowledge condition, participant can prepare for the task before stimulus presentation: its effects reflect endogenous executive control. In stimulus location foreknowledge condition, location of the stimuli can incur the exogenous activation: its effects associated with automatic control mechanism. The following conclusions could be drawn from our experiments:(1) There may be two components to the switch cost: one associated with preparation for the upcoming task through executive control and the associated with persisting activation of previous task-set through automatic control. The automatic activation incurred by the upcoming task has no effect on the switch cost.(2) In adequate preparation condition, residual cost primarily reflects the persisting activation of previous task-set. Prepare levels have no effect on the residual cost.(3) In inadequate preparation condition, prepare levels have effect on the endogenous preparation for a new task through executive control and not on persisting activation of previous task-set through automatic control.(4) Although foreknowledge allows preparation for both repeated and switched tasks, task switching has benefits over repeating the same task. The foreknowledge about task type has effect on switch cost but not about stimulus location.(5) There is an additive TSR process in switched tasks, but not in repeated tasks.