Conflicts during response selection affect response programming: reactions toward the source of stimulation.

Area of Science:

• Cognitive Psychology
• Human Motor Control
• Perception and Action

Background:

• The Simon effect demonstrates how irrelevant spatial information influences response selection.
• Conflict arises when stimulus location mismatches the required response, increasing reaction times (RTs).
• Movement parameters (MPs) offer a more detailed insight into the dynamics of this cognitive conflict.

Purpose of the Study:

• To investigate the relationship between RTs and MPs in the Simon effect.
• To examine how time pressure and response selection influence the Simon effect.
• To explore the temporal dynamics of conflict resolution in motor responses.

Main Methods:

• Participants performed a typical Simon task involving keypresses or pointing responses.
• Reaction times (RTs) and movement parameters (MPs), including trajectory deviations, were recorded.
• Experimental manipulations included varying time pressure and manipulating response selection timing.

Main Results:

• Pointing trajectories veered towards the imperative stimulus, with this bias decreasing as RTs increased.
• Time pressure reduced the Simon effect in RTs but not in MPs or their time course.
• Altering response selection timing affected the Simon effect in MPs and reversed its time course, without impacting RTs.

Conclusions:

• The time course of trajectory deviations in the Simon effect reflects the gradual resolution of response conflict.
• Independent Simon effects may be associated with distinct stages of response selection and programming.
• Movement parameters provide a sensitive measure for understanding the temporal dynamics of cognitive control.