The next step in optimising the stair horizontal-vertical illusion: does a perception-action link exist in older adults?

Skervin, TK ORCID logoORCID: https://orcid.org/0000-0001-6746-7420, Thomas, NM, Schofield, AJ, Hollands, MA, Maganaris, CN and Foster, RJ, 2021. The next step in optimising the stair horizontal-vertical illusion: does a perception-action link exist in older adults? Experimental Gerontology, 149: 111309. ISSN 0531-5565

[thumbnail of 1820855_Skervin.pdf]
Preview
Text
1820855_Skervin.pdf - Post-print

Download (941kB) | Preview

Abstract

Introduction: Tripping on stairs results from insufficient foot to step edge clearance and can often lead to a fall in older adults. A stair horizontal-vertical illusion is suggested to increase the perceived riser height of a step and increase foot clearance when stepping up. However, this perception-action link has not been empirically determined in older adults. Previous findings suggesting a perception-action effect have also been limited to a single step or a three-step staircase. On larger staircases, somatosensory learning of step heights may be greater which could override the illusory effect on the top step. Furthermore, the striped nature of the existing stair horizontal-vertical illusion is associated with visual stress and may not be aesthetically suitable for use on public stairs. These issues need resolving before potential future implementation on public stairs.

Methods: Experiment 1. A series of four computer-based perception tests were conducted in older (N=14: 70 ± 6 years) and young adults (N=42: 24 ± 3 years) to test the influence of different illusion designs on stair riser height estimation. Participants compared images of stairs, with horizontal-vertical illusions or arbitrary designs on the bottom step, to a plain stair with different bottom step riser heights and selected the stair they perceived to have the tallest bottom riser. Horizontal-vertical illusions included a previously developed design and versions with modified spatial frequencies and mark space ratios. Perceived riser height differences were assessed between designs and between age groups. Experiment 2. To assess the perception-action link, sixteen older (70 ± 7 years) and fifteen young (24 ± 3 years) adults ascended a seven-step staircase with and without horizontal-vertical illusions tested in experiment 1 placed onto steps one and seven. Foot clearances were measured over each step. To determine whether changes in perception were linked to changes in foot clearance, perceived riser heights for each horizontal-vertical illusion were assessed using the perception test from experiment 1 before and after stair ascent. Additional measures to characterise stair safety included vertical foot clearance, margins of stability, foot overhang, stair speed, and gaze duration, which were assessed over all seven steps.

Results: Experiment 1. All horizontal-vertical illusion designs led to significant increases in the perceived riser height in both young and older adults (12-19% increase) with no differences between age groups. Experiment 2. On step 7, each horizontal-vertical illusion led to an increase in vertical foot clearance for young (up to 0.8cm) and older adults (up to 2.1cm). On step 1 significant increases in vertical foot clearance were found for a single horizontal-vertical illusion when compared to plain (1.19cm increase). The horizontal-vertical illusions caused significant increases in the perceived riser height (young; 13% increase, older; 11% increase) with no differences between illusion design, group or before and after stair ascent. No further differences were found for the remaining variables and steps.

Conclusion: Results indicate a perception-action link between perceived riser height and vertical foot clearance in response to modified versions of the horizontal-vertical illusion in both young and older adults. This was shown with no detriment to additional stair safety measures. Further evaluating these illusions on private/public stairs, especially those with inconsistently taller steps, may be beneficial to help improve stair safety for older adults.

Item Type: Journal article
Publication Title: Experimental Gerontology
Creators: Skervin, T.K., Thomas, N.M., Schofield, A.J., Hollands, M.A., Maganaris, C.N. and Foster, R.J.
Publisher: Elsevier BV
Date: 1 July 2021
Volume: 149
ISSN: 0531-5565
Identifiers:
Number
Type
10.1016/j.exger.2021.111309
DOI
1820855
Other
Divisions: Schools > School of Science and Technology
Record created by: Laura Ward
Date Added: 03 Nov 2023 17:00
Last Modified: 03 Nov 2023 17:00
URI: https://irep.ntu.ac.uk/id/eprint/50261

Actions (login required)

Edit View Edit View

Statistics

Views

Views per month over past year

Downloads

Downloads per month over past year