Stopping Speed in the Stop-Change Task: Experimental Design Matters!

Area of Science:

• Cognitive Psychology
• Neuroscience
• Human Motor Control

Background:

• Inconsistent findings exist regarding motor response inhibition speed under foreknowledge versus no-foreknowledge conditions.
• Differences in experimental design are hypothesized as a source of this heterogeneity in previous research.

Purpose of the Study:

• To investigate whether the experimental design (block vs. event-related) influences the speed of motor response inhibition.
• To determine if foreknowledge of a stop signal affects inhibition speed differently depending on the task's design.

Main Methods:

• A modified stop-change task was employed across two experiments.
• Experiment 1 used a block design, separating foreknowledge and no-foreknowledge trials.
• Experiment 2 used an event-related design, intermingling both trial types.

Main Results:

• Stop signal reaction time (SSRT) was faster in the foreknowledge condition compared to the no-foreknowledge condition in the event-related design.
• No significant difference in SSRT was found between foreknowledge and no-foreknowledge conditions in the block design.
• Participants exhibited strategic slowing of go responses, particularly in the event-related foreknowledge condition (strategic delay effect), which correlated with SSRT.

Conclusions:

• Motor response inhibition speed is sensitive to strategic biases introduced by the experimental setup.
• The observed strategic delay effect in the event-related foreknowledge condition highlights the interplay between strategic adjustments and inhibitory control.