Eye-Head-Trunk Coordination While Walking and Turning in a Simulated Grocery Shopping Task

Area of Science:

• Human movement science
• Biomechanics
• Motor control

Background:

• Previous research established a specific sequence for body turns: eyes initiate movement, followed by the head, and finally the trunk.
• This sequence has been primarily observed in tasks involving proximal goals or explicit turning instructions.

Purpose of the Study:

• To investigate if the established eye-head-trunk turning sequence persists when turns are implicitly required for a distal goal.
• To determine if explicit instructions are necessary for the ordered execution of body turns.

Main Methods:

• Participants navigated a simulated supermarket to retrieve grocery items, requiring turns into aisles.
• The necessity of turns was implicit, not explicitly stated, to reach target shelves.
• Key metrics included the temporal delays between eye-head and head-trunk movements during turns.

Main Results:

• A consistent positive delay was observed between eye and head turns.
• A consistent positive delay was also found between head and trunk turns.
• The magnitude of these delays approached the upper range reported in prior literature.

Conclusions:

• The ordered sequence of eye-then-head-then-trunk turns is maintained even when the goal is distal.
• Implicitly required body turns adhere to the same sequential motor control principles as explicitly instructed turns.
• This suggests a robust underlying motor program governing body orientation regardless of goal proximity or instruction type.