Perceived timing of postural instability onset.

Area of Science:

• Human balance and postural control
• Human sensory perception
• Human psychophysics

Background:

• Previous studies using Temporal Order Judgment (TOJ) tasks suggest a significant delay in perceiving postural instability onset relative to auditory stimuli.
• Methodological concerns, particularly unbalanced stimulus onset asynchrony (SOA) distributions, exist in prior research on postural instability perception.

Purpose of the Study:

• To investigate if the point of subjective simultaneity (PSS) differs between unequally and equally distributed SOA conditions.
• To determine if the perception of postural perturbation onset is delayed compared to true simultaneity.

Main Methods:

• A repeated measures design with 10 participants using a TOJ task.
• Two SOA distributions were presented: distribution 1 (unequally distributed) and distribution 2 (equally distributed).
• Paired t-tests and one-sample t-tests were used to analyze PSS differences and delays.

Main Results:

• Distribution 1 showed a perceived delay of postural instability onset by 20.34 ms.
• Distribution 2 resulted in a perceived delay of the auditory stimulus by 3.52 ms.
• Neither condition demonstrated a significant difference from each other or from true simultaneity (0 ms).

Conclusions:

• The perception of postural instability onset is not inherently slow, contrary to previous assumptions.
• Controlling methodological parameters, such as SOA distribution, is critical for accurate sensory cue examination.
• Findings contribute to a better understanding of balance control and may inform falls prevention strategies.