Tuning of Standing Postural Responses to Instability and Cost Function

Area of Science:

• Biomechanics
• Human Motor Control
• Risk Perception

Background:

• Maintaining upright stance requires continuous adaptation to instability.
• Daily movements often occur in environments with varying risks and failure costs.

Purpose of the Study:

• To test if individuals estimate both probability and cost of failure during postural control.
• To determine if these estimates influence postural responses in risky situations.

Main Methods:

• A snowboard riding simulation assessed postural control in a risky environment.
• Cost functions were manipulated by altering penalties for deviating from the track.
• Uncertainty was modified by adjusting postural response gain on a rocker board.

Main Results:

• Participants continuously evaluated environmental cost functions and adjusted postural responses to mitigate risk.
• Postural adjustments were made even when the probability of failure was very low.
• Estimates of failure probability correlated with inherent postural instability.
• Large probabilities of failure were often overestimated, leading to biomechanically constrained postures.

Conclusions:

• Individuals dynamically estimate the cost and uncertainty of failure to modulate postural control.
• Postural responses are tuned to minimize the risk of falling, particularly when the cost of failure is significant.
• Risk perception and estimation play a crucial role in adaptive postural adjustments.