Motor "laziness" constrains fixation selection in real-world tasks.

Area of Science:

• Cognitive Neuroscience
• Human Motor Control
• Visual Perception

Background:

• Natural human behavior involves coordinated eye, head, and body movements for environmental information gathering.
• Traditional lab studies with restraints and static stimuli may not fully capture real-world visual search mechanisms.
• The influence of laboratory-discovered fixation selection mechanisms, like inhibition-of-return (IOR), on everyday behavior remains unclear.

Purpose of the Study:

• To investigate eye movement patterns and fixation selection in natural, real-world tasks.
• To determine if inhibition-of-return (IOR) or other mechanisms dominate everyday visual behavior.
• To explore the balance between minimizing motor costs and maximizing rewards in visual exploration.

Main Methods:

• Participants performed nine diverse real-world tasks (e.g., driving, searching, building) while wearing a mobile eye tracker.
• Analysis of 169 recordings totaling 26.6 hours of eye movement data.
• Development of a computational model to simulate scanpath generation based on observed distributions.

Main Results:

• Across most tasks, participants frequently returned to recently viewed locations, showing facilitation rather than inhibition of return.
• Shorter saccade latencies were observed before return saccades compared to forward saccades.
• Center biases in fixation position and duration relative to head orientation were evident, supporting a 'laziness' hypothesis.

Conclusions:

• Human visual search in natural environments appears to prioritize minimizing motor effort, leading to a bias for returning to recently viewed areas.
• While motor cost minimization is a primary driver, task-specific demands can modulate this, allowing for mechanisms like IOR when reward maximization is critical.
• The brain dynamically balances motor effort conservation with reward-seeking strategies, with the optimal balance varying by task requirements.