Arm Posture Changes and Influences on Hand Controller Interaction Evaluation in Virtual Reality

The effects of target sizes on biomechanical and cognitive load and task performance of virtual reality interactions

This study evaluated the effects of target sizes on biomechanical and cognitive load and the performance of virtual reality (VR) interactions. In a repeated-measures laboratory study, each of the twenty participants performed standardised VR tasks with three different target sizes: small, medium, and large. During the VR tasks, biomechanical load in the neck and shoulders (joint angles, joint moments, and muscle activity), cognitive load (perceived workload and cognitive stress), and task performance (completion time) were collected. The neck and shoulder joint angles, joint moments, and muscle activities were greater with the large targets compared to the medium and small targets. Moreover, the larger VR targets caused greater temporal demand and longer task completion time compared to the other target sizes. These findings indicate that target sizes in VR interfaces play important roles in biomechanical and cognitive load as well as task performance.

Performance on a target acquisition task differs between augmented reality and touch screen displays

Target acquisition tasks quantify human motor and perceptual abilities while performing discrete tasks to support interface design and sensorimotor assessments. This study investigated the effects of display, Touchscreen and Augmented Reality (AR), on a standardized 2D multidirectional target acquisition task. Thirty-two participants performed the target acquisition task with both modality types and at two indexes of difficulty. The touchscreen modality yielded improved performance over AR as measured by accuracy, precision, error rates, throughput, and movement time. Throughput using the nominal index of difficulty was 10.12 bits/s for touchscreen and 3.11 bits/s for AR. AR designers can use the results to improve performance when designing AR interfaces by selecting larger buttons when accuracy and efficiency are required and by embedding perception cues to button target surfaces such as depth and proximity cues.

Effects of error rates and target sizes on neck and shoulder biomechanical loads during augmented reality interactions

Augmented reality (AR) interactions have been associated with increased biomechanical loads on the neck and shoulders. To provide a better understanding of the factors that may impact such biomechanical loads, this repeated-measures laboratory study evaluated the effects of error rates and target sizes on neck and shoulder biomechanical loads during two standardized AR tasks (omni-directional pointing and cube placing). Twenty participants performed the two AR tasks with different error rates and target sizes. During the tasks, angles, moments, and muscle activity in the neck and shoulders were measured. The results showed that the target sizes and error rates significantly affected angles, moments, and muscle activity in the neck and shoulder regions. Specifically, the presence of errors increased neck extension, shoulder flexion angles and associated moments. Muscle activity in the neck (splenius capitis) and shoulder (anterior and medial deltoids) also increased when the errors were introduced. Moreover, interacting with larger targets resulted in greater neck extension moments and shoulder abduction angles along with higher muscle activity in the splenius capitis and upper trapezius muscles. These findings indicate the importance of reducing errors and incorporating appropriate target sizes in the AR interfaces to minimize risks of musculoskeletal discomfort and injuries in the neck and shoulders.