Maintenance of upright balance involves interplay between sensory (somatosensory, vestibular and visual) inputs and neuro-motor outputs. Visual spatial perception (VSP) of vertical and horizontal orientation plays a significant role in the maintenance of upright balance. For this experiment, a custom designed computer program randomly generated images of horizontal and vertical lines at various angles to 60 industrial workers (38.97±9.76 years). Half of the workers had more than three years of experience working on inclined and/or elevated surfaces such as roofs, ramps, docks and scaffolding. The main effects investigated included within subject factors of standing surface inclination (0°, 14° and 26°), job experience (number of months working on inclined and/or elevated surfaces), and workload (0%, 50% or 100%). Immediately after the postural workload the worker was asked their perceived sense of exertion (PSE) level and rank of bodily discomfort. The workers then stood on an inclined surface and were presented 40 random angles. The VSP outcome measure used was the Count of correct responses to the angles presented. The postural workload, PSE and discomfort parameters were analyzed in separate models and backward elimination was applied to drop insignificant covariates (p>0.05). The inclination did not have a significant effect (p>0.05) on VSP, but the parameter estimates indicated that on the inclined surfaces, workers tended to have less correct responses. The postural workload significantly affected the VSP (p<0.03) and the PSE (p=0.067) and discomfort (p=0.139) were not significant. All factors indicated that with increased workload, lest correct responses were given. Finally, job experience was found to have a positive effect (p<0.025) on VSP demonstrating that workers with more months of experience had more correct responses. These results indicate that job experience increases accurate VSP, while workloads and inclined work surfaces decrease accurate VSP responses.
展开▼
