The preparation effect in task switching: carryover of SOA

Area of Science:

• Cognitive Psychology
• Neuroscience
• Human Behavior

Background:

• Task-switching studies commonly observe switch preparation, where increased stimulus onset asynchrony (SOA) lessens the cognitive cost of switching tasks.
• This preparation effect suggests a mechanism that benefits from advance preparation time between task cues and stimuli.

Purpose of the Study:

• To investigate the relationship between switch preparation and within-subjects manipulations of SOA.
• To determine if the preparation effect is contingent on the variability or predictability of SOA across trials.

Main Methods:

• Three experiments were conducted manipulating SOA within and between subjects.
• Experiment 1 randomized SOA within subjects; Experiment 2 blocked SOA within subjects; Experiment 3 used between-subjects SOA manipulation.

Main Results:

• Switch preparation was more pronounced when SOA varied between trials (Experiment 1).
• Switch preparation occurred in blocked SOA conditions but not on the initial block (Experiment 2).
• No switch preparation was detected when SOA was manipulated between subjects (Experiment 3).

Conclusions:

• Findings support an encoding view of cognitive control, suggesting preparation mechanisms are sensitive to SOA variability.
• A putative switching mechanism appears to react sluggishly when exposed to a single, consistent SOA, highlighting the role of predictability in cognitive control.