The effects of target size and error rate on the cognitive demand and stress during augmented reality interactions.

This study investigated the effects of target size and error rate on cognitive demand during augmented reality (AR) interactions. In a repeated-measures laboratory study, twenty participants performed two AR tasks (omni-directional pointing and cube placing) with different target sizes and error rates. During the AR tasks, we measured cerebral oxygenation using functional near-infrared spectroscopy (fNIRS), perceived workload using the NASA-TLX questionnaire, stress using the Short Stress State Questionnaire, and task performance (task completion time). The results showed that the AR tasks with more interaction errors increased cerebral oxygenation, perceived workload, and task completion time while the target size significantly affected physical demand and task completion time. These results suggest that appropriate target sizes and low system errors may reduce potential cognitive demand in AR interactions.

Influence of the wearable posture correction sensor on head and neck posture: Sitting and standing workstations.

BACKGROUND: Flexed head and neck postures are associated with the development of neck pain in the office environment. There is little evidence regarding whether a wearable posture sensor would improve the head and neck postures of office workers. OBJECTIVE: The aim of this study was to evaluate the effect of the wearable posture sensor on the posture and physical demands on the head and neck during office work. METHODS: Nineteen participants performed a typing task with and without the wearable sensor in the sitting and standing positions. They were allowed to adjust their workstation during the experiment based on a psychophysical method. The flexion angles of the head and neck, the gravitational moment on the neck, and the positions of the workstation components were measured. RESULTS: On average, participants with the wearable sensor had 8% lower neck flexion angles and 14% lower gravitational moments on the neck than those of participants without the wearable sensor. The effect of the wearable sensor on reducing postural stress of the neck was more significant when using the standing workstation compared to the sitting workstation. CONCLUSIONS: The wearable posture sensor could be an effective tool to alleviate the postural stress of the neck in the office setting.

The effect of feedback and practice on the acquisition of novel speech behaviors.

PURPOSE: This study examined the effect of manipulating several parameters of motor learning theory on participants' phonetic acquisition and retention of utterances in a foreign language (Korean). METHOD: Thirty-two native English-speaking participants naïve to the Korean language were each given 10 Korean sentences to practice and learn. The independent variables in the study were the number of practice trials and the feedback schedule. The participants listened to sentences delivered by a native speaker and received feedback according to the schedule. Participant responses were then judged by a panel of native Korean speakers in terms of their intelligibility, naturalness, and precision. RESULTS: The combination of 20% feedback and 100 practice trials was more effective than other combinations of feedback and practice trial schedule for the retention of novel phonetic productions of Korean phrases both 1 day after training and 1 week later. CONCLUSIONS: These findings are in agreement with previously reported applications of motor learning-guided principles on the acquisition of motoric skills. These findings may have direct implications for both second-language learning and the treatment of neuromotor speech disorders such as apraxia of speech.