Visual Feedback Increases Accuracy in Active Shoulder Joint Angle Replication Task

Abstract

Although visual feedback is typically occluded in joint position sense (JPS) research to avoid the confounding influence of an additional sense, it has not been established that vision impacts JPS accuracy. The purpose of this research was to examine the effect of added visual feedback on absolute error during a shoulder joint angle replication task. It was hypothesized that the addition of visual feedback would result in lower absolute error when compared no visual feedback. Data were collected from eighteen subjects using an Apple iPod Touch® attached to the upper arm of a seated subject. The application guided the subject to a target angle with high and low tones, the subject memorized the position, then replicated it without auditory feedback. Target angles of 50°, 70°, and 90° were used with each presented four times for four visual conditions (open vs. closed in guided replicating stages). Results revealed a main effect (p < 0.001) of visual condition on absolute error, with the added visual feedback reducing absolute error by 1.5°. Additionally, a main effect (p < 0.001) of target angle on absolute error was found with reduced error at 90°, in consistency with previous research. Based on these results, the hypothesis that added visual feedback would reduce absolute error in a shoulder joint angle replication task was supported.