Principal Supervisor: Professor Andrew SchofieldLink opens in a new window

Co-supervisor: Tim Meese (40%), Antonio Fratini (10%), Richard Foster (External)

PhD project title: Step decent in older adults: using VR to explore the role of 3D vision, cognitive load, and social context

University of Registration: University of Aston

Project outline:

Background: Susceptibility to falls is a feature of healthy aging. Falls on steps are a major cause of disability and a leading cause of mortality among people aged over 75 (Fuller 2000). The visual appearance of steps is known to affect stepping behaviour in younger and older adults (Skervin et al 2021). However, relatively subtle texture cues that influence toe clearance in younger adults are missed by older adults (Schofield et al, 2017). Eye movement studies suggest a close coupling between eye-gaze and step dynamics (Hollands et al, 1995). These characteristic patterns of looking also vary with age suggesting that older adults may be acquiring visual information too late to correct their gait (Young & Hollands, 2012). Finally, older adults are known to display anxiety when navigating steps affecting both eye movements and gate (Young et al., 2012).

Most of the work on the visual guidance of step dynamics has considered step climbing. However, from a visual perspective, step decent is the harder task since the informative risers are hidden from view leading to a greater reliance on stereoscopic (3D) cues to judge step height. We know that older adults have relatively poor 3D vision (Greene & Madden, 1987) and anecdotally they find judging step height prior to decent difficult; leading to anxiety.

Thus, there are three factors that might cause older adults difficulty when navigating steps. First, declines in visual performance may itself influence judgements of step height especially during decent. Second, declining visual performance may be compensated by the deployment of limited cognitive resources but this may then impede other processes such as route planning and eye movement control (Reuter-Lorenz & Cappell, 2008). Third, older adults may be more anxious than younger adults when approaching steps leading to a lack of attention, sub-optimal eye movements and poor judgements of step height.

Objectives:

We aim to:

Determine the effects of improvised 3D vision on step decent.

Understand the influence of cognitive load and cognitive cuing on step dynamics.

Explore the influence of situational cue and heightened anxiety on step dynamics.

Consider the interrelations between these factors in younger and older adults.

Method:

Observers will be asked descend (or climb) a physical step embedded in a virtual reality environment (VR-CAVE). We will use healthy younger, and older adults manipulating visual, cognitive and situational cues so as to explore the relative importance of sensory processing, cognitive processing and anxiety on stepping tasks. Visual cues will be manipulated so as to enhance or reduce the availability of cues to depth. Cognitive resources will be manipulated via a secondary task such as counting the number of spots projected onto the field of view while approaching the step. The spots may be projected so as to either encourage or inhibit optimal eye-moments. Finally, situational cues in the form of pleasant and unpleasant environments will be used to induce or reduce stress during the navigation task. The immersive nature of the CAVE environment will make such manipulations realistic and compelling.

We will use kinematic methods to measure gate dynamics and stepping accuracy. Stress will be measured with galvanic skin response and heart rate monitors.

 

References:

Fuller GF (2000) Am Fam Phys 61,2159–2168.

Greene H., & Madden D, (1987) Am. J.of Optometry and Physiological Optics. 64,749–753.

Hollands MA, Marplehorvat DE, Henkes S, Rowan AK (1995) J Mot Behav 27,155–163.

Reuter-Lorenz PA, & Cappell KA (2008) Current Directions in Psy. Sci. 17,177-182.

Schofield, AJ, Curzon-Jones, B & Hollands, MA (2017) Exp. Brain Res, 235, 573-583.

Skervin, T. K., Thomas, N. M., Schofield, A. J., Hollands, M. A., Maganaris, C. N. & Foster, R. J., (2021), Exp. Gerontology. 149, 111309

Young W.R., Wing A.M., Hollands M.A., (2012). J. of Gerontology - Series B, 67, B:43-51.

Young WR, Hollands MA (2012) Gait Posture 36,477–481.

BBSRC Strategic Research Priority: Integrated Understanding of Health - Ageing.

Techniques that will be undertaken during the project:

Virtual reality,

kinematics,

Psychophysics,

Electrophysiology

 

Contact: Professor Andrew SchofieldLink opens in a new window