Perceived timing of postural instability onset

Background This study examines the perceived timing of postural instability onset, a crucial aspect of balance. Previous research using Temporal Order Judgment (TOJ) tasks found that postural perturbations need to occur significantly earlier than an auditory reference stimulus for individuals to perceive them as simultaneous. However, there are methodological concerns with this prior work, specifically regarding an unbalanced stimulus onset asynchrony (SOA) distribution. Research question Does the point of subjective simultaneity (PSS) between postural perturbation onset and an auditory reference stimulus differ for equal versus unequal SOA distributions? Methods A repeated measures design was utilized, presenting two different SOA distributions to 10 participants using a TOJ task during both the equal (72 trials) and unequal (88 trials) SOA distributions. Paired t-tests were used to determine if there was a significant difference between the PSS of the equal and unequal SOA distributions. Additionally, one-sample t-tests were performed on the PSS values of both the equal and unequal SOA distributions in comparison to 0ms (defined as true simultaneity) to determine if perceptual responses were delayed. Results The results indicate that the unequal SOA distribution resulted in a perceived delay of postural instability onset by 20.34ms, while the equal SOA distribution resulted in a perceived delay of the auditory stimulus of 3.52ms. However, neither condition was significantly different from each other nor from true simultaneity. Significance These findings suggest that the perception of postural instability onset is not slow, as previously thought, and highlight the importance of controlling methodological parameters when investigating sensory cues. This knowledge highlights the importance of controlling methodological parameters when investigating the perception of sensory cues and will help inform falls prevention strategies. ### Competing Interest Statement The authors have declared no competing interest.