Direct perception of action-scaled affordances: the shrinking gap problem

Area of Science:

• Perception science
• Locomotion dynamics
• Human-computer interaction

Background:

• Perceiving affordances, or action possibilities, is crucial for navigation.
• Understanding how movement capabilities influence gap passability is key for safe locomotion.

Purpose of the Study:

• To investigate how individuals perceive the passability of shrinking gaps based on their movement capabilities.
• To introduce a novel optical invariant for specifying minimum required locomotor speed through dynamic gaps.

Main Methods:

• Subjects navigated a virtual environment with converging obstacles.
• Judgments of gap passability were recorded.
• Visual and non-visual self-motion information were independently manipulated on specific trials.

Main Results:

• A new optical invariant was introduced to quantify the minimum speed for safe gap passage.
• Both visual and non-visual self-motion cues contribute to detecting information about required walking speed.
• Catch trials revealed independent contributions of visual and non-visual information.

Conclusions:

• The perception of affordances for gap traversal relies on integrated visual and non-visual self-motion information.
• This research advances the understanding of dynamic environmental perception and locomotion control.