Questions: Task Switching and Executive Control Costs

Question 1

Participants are given a generous preparation interval and told exactly which task is coming next before each switch trial. Responses on switch trials are still slower than on repeat trials. What does this residual switch cost demonstrate?

• A. The participants failed to use the preparation interval effectively
• B. Switching involves a cognitive cost that advance preparation cannot fully pre-resolve
• C. Long preparation intervals paradoxically increase switch costs through over-preparation
• D. Switch costs are entirely due to surprise, and the design failed to eliminate surprise

Answer: (B)

The residual switch cost — the cost that persists even after full advance preparation — is the central theoretical finding of task-switching research. It shows that switching is not merely about being caught off guard or having insufficient time to prepare. There is a proactive interference component: the prior task-set persists and must be overcome at the moment of the switch itself. Preparation can accomplish partial reconfiguration but cannot dissolve the carryover from the previous task, revealing a genuine architectural cost of cognitive flexibility.

Question 2

What distinguishes a 'switch cost' from a 'mixing cost' in task-switching paradigms?

• A. Switch costs occur on error trials; mixing costs occur on correct trials
• B. Switch costs are the penalty on task-switch trials relative to repeat trials; mixing costs are the slowing on all trials in a mixed block relative to a pure single-task block
• C. Switch costs reflect response competition; mixing costs reflect perceptual interference
• D. Mixing costs apply only when tasks share stimulus modalities; switch costs apply otherwise

Answer: (B)

Switch costs capture the specific penalty of the task-transition — slower responses and higher errors on switch trials versus repeat trials within the same block. Mixing costs capture the broader overhead of holding two task-sets simultaneously: even on repeat trials in a mixed block, responses are slower than in a pure single-task block. Mixing costs reflect the standing executive demand of maintaining two tasks in readiness, independent of whether a switch just occurred. Together they reveal two distinct sources of cognitive cost from task flexibility.

Question 3

If a person knows exactly which task is coming next and is given a long preparation interval, switch costs will be eliminated.

• T. True
• F. False

Answer: False

This is one of the most replicated findings in executive control research. Longer preparation intervals reduce switch costs — reconfiguration can be partially completed in advance — but residual costs reliably remain. The residual reflects task-set carryover: the prior task-set persists and must be overcome at the moment of switching, a process that cannot be fully accomplished before the switch occurs. If switch costs were entirely due to insufficient preparation, long forewarning would eliminate them entirely — the fact that it doesn't reveals a genuine irreducible cost.

Question 4

Switching between two tasks that compete for the same cognitive resources — same stimulus dimension, same response channel — typically produces larger switch costs than switching between tasks using entirely different inputs and outputs.

• T. True
• F. False

Answer: True

Switch costs scale with the degree of competition between task-sets. When tasks share representations or response channels, the prior task-set more powerfully interferes with the incoming one — the carryover is stronger and harder to overcome. Tasks using different modalities, different effectors, or different decision rules compete less, producing smaller proactive interference and therefore smaller switch costs. This relationship is informative about the mechanism: it is not the act of switching per se that is costly, but the interference from a prior task-set that occupies shared cognitive resources.

Question 5

Why does the residual switch cost — the cost remaining even after full advance preparation — matter for understanding the cognitive architecture of executive control?

Model answer: The residual switch cost shows that cognitive flexibility has an irreducible cost not attributable to surprise or inadequate preparation. If reconfiguration could be fully pre-completed, long forewarning would eliminate switch costs; it doesn't. This means the prior task-set persists as proactive interference that must be resolved at the moment of transition — the cognitive system cannot simply 'delete' the previous task context. This reveals something fundamental about executive control: flexibility is not free, and the cost of changing cognitive context is partly inescapable, providing a window into the architecture of how the executive system manages competing task demands.

This finding led researchers to distinguish two separable mechanisms: task-set reconfiguration (proactive preparation, reducible by forewarning) and task-set carryover or proactive interference (residual from the prior task, not fully reducible). The two can be experimentally dissociated, and the residual component localizes to the moment of switching itself — the prior task must be actively inhibited or overwritten, a process that can begin but not complete before the new trial begins.