Cancellation tasks are commonly used assessment tools to detect unilateral neglect. Bell’s Test, one of the most commonly administered cancellation tasks, requires individuals to quickly and accurately identify “bells” randomly placed in an array of symbols. The reliability of Bells Test conducted with a paper and pencil is well established. A newly developed, commercial software application, allows Bell’s Test to be administered in fully immersive virtual reality environment. PURPOSE: The purpose of this study was to measure the reliability of the Bell’s Test using a virtual reality (VR) system and to establish the level of agreement between the pen-paper and VR administration. METHODS: Fourteen apparently healthy individuals between the age of 24 – 73y volunteered (47.9±20.7y; 166.0±5.2cm; 77.5±16.3kg). Subjects were excluded if they had a history of concussion or had perceptual or visual deficits. Participants completed Bell’s Test a total of four times. The first time, it was completed with a pen-paper (PP). Then, participants completed an initial assessment in VR (VRbase); the same test was administered again in VR one-hour (PostVR1hr) and one-week (PostVR1wk) post baseline. Realization time, total time, and the number of errors committed in the right and left field of view were recorded. Cronbach’s alpha was computed on realization and total time in all VR conditions. Additionally, an ANOVA with repeated measures was used to determine differences in PP, VRbase, PostVR1HR, and PostVR1Wk. The Holms-Sidak method was used to identify pairwise differences. Alpha was set at pa priori. RESULTS: Reliability for realization time for the Bell’s test conducted in VR was acceptable (α=0.79). There was, however, a significant difference between trials (F=6.65; p=0.013). VRbase (29.25±8.11s) was significantly different than PostVR1HR (15.52±4.30; p=0.006). and VRpost1wk (21.24±5.89s; p=0.01). Additionally, PP realization time (15.31±4.25s) was significantly different than PostVR1HR (p=0.02) and PostVR1WK (p=0.03). Reliability for total time for the Bell’s test conducted in VR was good. (α=0.82). There was not a significant difference between the trials (F=4.34; p=0.06) for VRbase(24.1±6.7s), PostVR1HR (45.44±12.6) or VRpost1wk(p=0.06). However, there was a significant difference found in PPtotal time taken and VR1wk with the (p=0.03). The average number of left side omitted bells was 0.50±0.65; 0.07±0.26; 0.07±0.26; 0.14±0.36 for PP, VRbase, Post VR1HR, and PostVR1WK; respectively. The number of bells omitted on the right side was 0.50±0.85, 0.21±0.57, 0.14±0.36, for 0.14±0.36 for PP, VRbase, PostVR1HR, and PostVR1WK; respectively. CONCLUSION: These data indicate that the reliability of the Bell’s Test for the realization time is acceptable, and the total time reliability was good in the virtual reality system. Healthy individuals performing the Bell’s Test in VR show slight improvements one hour after baseline, but there was no difference after one week. More data are needed within different age groups to determine reliability in young and older individuals. Additionally, future studies are required to determine the reliability of Bell’s Test in VR for individuals suffering from neurological injuries or diseases.



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