Meehan Michael, Razzaque Sharif, Insko Brent, Whitton Mary, Brooks Frederick P
Stanford University, California 94305-8610, USA.
Appl Psychophysiol Biofeedback. 2005 Sep;30(3):239-58. doi: 10.1007/s10484-005-6381-3.
A common measure of effectiveness of a virtual environment (VE) is the amount of presence it evokes in users. Presence is commonly defined as the sense of being there in a VE. There has been much debate about the best way to measure presence, and presence researchers need and have sought a measure that is reliable, valid, sensitive, and objective. We hypothesized that to the degree that a VE seems real, it would evoke physiological responses similar to those evoked by the corresponding real environment, and that greater presence would evoke a greater response. To examine this, we conducted four experiments, each of which built upon findings that physiological measures in general, and heart rate in particular, are reliable, valid, sensitive, and objective presence measures. The experiments compare participants' physiological reactions to a nonthreatening virtual room and their reactions to a stressful virtual height situation. We found that change in heart rate satisfied our requirements for a measure of presence, change in skin conductance did to a lesser extent, and that change in skin temperature did not. Moreover, the results showed that significant increases in heart rate measures of presence appeared with the inclusion of a passive haptic element in the VE, with increasing frame rate (30 FPS > 20 FPS > 15 FPS) and when end-to-end latency was reduced (50 ms > 90 ms).
虚拟环境（VE）有效性的一个常见衡量标准是它在用户中引发的临场感程度。临场感通常被定义为在虚拟环境中身临其境的感觉。关于衡量临场感的最佳方法存在很多争论，临场感研究人员需要并一直在寻找一种可靠、有效、灵敏且客观的衡量标准。我们假设，在一定程度上，虚拟环境看起来越真实，它引发的生理反应就会越类似于相应真实环境引发的反应，并且更强的临场感会引发更大的反应。为了验证这一点，我们进行了四项实验，每项实验都基于这样的发现：一般来说生理测量，尤其是心率，是可靠、有效、灵敏且客观的临场感测量指标。这些实验比较了参与者对一个无威胁的虚拟房间的生理反应以及他们对一个有压力的虚拟高处情境的反应。我们发现，心率变化满足我们对临场感测量指标的要求，皮肤电导率变化在较小程度上满足要求，而皮肤温度变化则不满足。此外，结果表明，随着虚拟环境中加入被动触觉元素、帧率增加（30帧每秒>20帧每秒>15帧每秒）以及端到端延迟降低（50毫秒>90毫秒），心率测量的临场感显著增加。
