Reaching movements are automatically redirected to nearby options during target split

Area of Science:

• Neuroscience
• Motor Control
• Cognitive Psychology

Background:

• Motor behavior frequently involves navigating environments with multiple, dynamic goal options.
• Understanding how actions adapt to changing targets is crucial for explaining real-world motor control.

Purpose of the Study:

• To investigate target selection mechanisms during ongoing reaches when presented with multiple options.
• To compare motor responses to single vs. dual target replacements during reaches.

Main Methods:

• Participants performed reaching movements where the initial target was either replaced by a single flanking target (jump trials) or two flanking targets (split trials).
• Natural reach tendencies and instructed target choices were analyzed, alongside reaction times and muscle responses.

Main Results:

• Participants exhibited a strong preference for the target nearest the original location in split trials.
• Reaction times were longer in split trials (~200 ms) compared to jump trials (~150 ms).
• Attempting to select the farther target in split trials resulted in significantly more errors (~50%) than selecting the nearer target (~15%).

Conclusions:

• Online target selection is automatically influenced by the spatial arrangement of available options.
• This automatic selection process is less efficient and slower than redirecting to a single target.
• Overriding the near-target bias requires cognitive effort, leading to performance decrements.