Bridging the Gap Between Mobility Perception and Performance for Aging Manual Wheelchair Users

Abstract

The population of aging adults is rapidly increasing worldwide. Inequity in mobility independence alongside increasing disability incidence during aging reduce quality of life and participation- which are critical as the desire and need to work into older age rises. Manual wheelchairs (MW) have become increasingly relied upon by aging adults to support mobility loss. Therefore, in order to support safe and equitable MW use within the aging population, there is a need to design effective and practical environment-based interventions that are applicable to a large range of manual wheelchair users (MWUs). This dissertation applied a novel integration of human factors engineering and motor control theories to improve mobility task-environments and the corresponding design/evaluation process to better include the needs of aging MWUs. In doing so, MW incidence period and simulated impairment (SI) were also distinguished to investigate the usefulness and validity, respectively, within research and design. Our findings show that interventions of simple, augmented visuospatial information within path-following environments successfully facilitated underlying somatoperception and somatorepresentation processes for MWUs. Specifically, the top-down intervention improved MWU ability to align their assumed frustration with their perceived frustration associated with a movement task (from 80% difference in Baseline to 29% with the intervention), which is necessary to promote confidence and reduce self-limited participation. Bottom-up interventions improved the congruency between participants’ perception of performance and the objective measure of movement accuracy (e.g., collisions committed) was improved as high as 28% (percent increase; resulting in correlation up to r = 0.88 among MWUs) by the BU interventions. in addition, MWUs with later-in-life incidence no longer committed more collisions than those with earlier-in-life incidence (LL: 1.22(1.81) collisions in the 6m straight line displacement; EL: 0.57 (0.12)) in the presence of both top-down (LL: 0.66(1.11); EL: 0.33(0.49)) and bottom-up interventions (LL: 0.44(0.89); EL: No collisions observed). Further, this work revealed the invalidity/bias of using SI in both research and design endeavors, as the space required to perform a common maneuvering task was significantly less for the SI (7.0cm, CI95: 0.8) than the MWUs (8.9cm, CI95: 2.2). SI participants also commented on very different themes than the MWUs (“a fun experience” vs. “reminders of stressful situations faced in daily life”, respectively), highlighting differences in somatorepresentations and relevant task stressors between the two groups. In sum, this dissertation showcased how concepts borrowed from motor control theory offers new and attractive perspectives for human factors and accessibility research. This work offers recommendations to design and assess inclusive environment-based, augmented visuospatial feedback interventions that effectively consider underlying sensorimotor processes and reveal simulation of impairment cannot be a surrogate to represent the reality of MWUs in research.