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Background: Vision can significantly impact both the perception and behaviour related to postural control. This study examines the influence of vision on the perception of postural instability onset. Previous research employing Temporal Order Judgment (TOJ) tasks to investigate the perceived timing of postural perturbation onset has not incorporated visual cues. Research question: Does the presence of visual feedback affect the point of subjective simultaneity (PSS) between postural perturbation onset and an auditory reference stimulus and does this additional sensory cue increase TOJ precision? Methods: Using a lean-and-release paradigm, 10 participants were exposed to postural perturbations in both eyes closed (EC) and eyes open (EO) conditions using a TOJ task where they indicated whether they perceived postural instability onset or sound onset as occurring first for each trial. Separate paired t-tests between EC and EO PSS and just noticeable difference (JND) values were used. One-sample t-tests were also used on PSS values for both conditions, comparing them to 0ms (true simultaneity). Results: The EC condition demonstrated a perceived delay of postural instability onset by 25.78 ms, while the EO condition showed a perceived delay of the auditory stimulus by 12.33 ms. However, no significant differences were found between the conditions or in comparison to true simultaneity. Mean JND values for EC (39.88 ms) and EO (46.48 ms) were not significantly different, suggesting visual information does not affect response precision for this task under these conditions. Significance: These findings indicate that visual information does not significantly affect the perception of postural instability onset. This suggests that visual information may play a limited role in the early perceptual stages of postural instability.

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.

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