听觉刺激对虚拟环境中空间压缩的影响

Effect of auditory stimulus on distance compression in virtual reality

人们往往会低估虚拟环境中空间的距离(空间压缩)。早期研究发现视听刺激的不一致会改善空间压缩,但听觉刺激在其中的作用及其影响效果需进一步研究。本研究首先探究了听觉刺激的有无对空间压缩的影响,接着操控视听刺激之间的物物距离进一步探究其对空间压缩的影响和改善。研究发现听觉刺激以两种方式影响空间压缩:听觉刺激的存在可以改善空间压缩;空间压缩与视听刺激的物物距离负相关。研究建议为了改善空间压缩,视听刺激应当同时呈现且物物距离至少为1 m。

Distance compression in virtual reality(VR), which will lead to a distortion of fine manipulation in practical application, depicts that people tend to underestimate the spatial distance of visual stimuli in virtual environments. The apparent perceived differences between virtual and real environments break the immersive experiences and lower users’ acceptance. Therefore, it is crucial to ameliorate the distance compression to increase the fidelity and ultimately promote the wider application of VR. Capitalizing on the fact that distance compression is a multiple modality phenomenon and occurs for auditory and visual stimuli, researchers reported that the distance judgment in VR would get more accurate when the positions of auditory and visual stimuli were incongruent. However, it is unclear to what extent the incongruency is to get effective amelioration. In this study,we aimed to completely examine the effect of the auditory stimulus on distance compression in VR. We presumed that the larger the incongruency was, the better amelioration obtained.We used the HTC Vive Pro to render the virtual environment and the build-in headphone to present auditory stimulus. Thirty participants were recruited to perform a distance judgment task. We first controlled the presence or absence of the auditory stimulus. We also varied the egocentric distance of visual stimulus(3 m, 4 m, 5 m).Then, we controlled the incongruency of the audio-visual condition, that is, the exocentric distance between auditory and visual stimuli(0.5 m, 1 m, 1.5 m, 2 m). Each block consisted of 30 consecutive trials, wherein the reference visual stimulus was presented at the beginning 5 s. Participants were asked to judge whether the following adjust stimulus was nearer or farther than the reference stimulus. The egocentric distance would be adjusted according to the response of the prior trial. The egocentric distance of the adjust stimulus in the last trial was referred to as the ultimate distance judgment for the initial reference stimulus.We found that the auditory stimulus affected the distance compression in two ways. First, the distance compression under the audio-visual condition was smaller than that under the visual-only condition(F(1, 29) =4.05, p = 0.054, ηp2 = 0.12), especially when the egocentric distance of the visual stimulus was large(4 m:difference = 1.8%, t =-1.59, df = 29, p = 0.062;5 m: difference = 1.6%, t =-1.85, df = 29, p = 0.037). Second,we formulated the relationship between the exocentric distance between auditory and visual stimuli and the distance compression rate, which was calculated by subtracting the perceived egocentric distance from the physical egocentric distance and then dividing it by the physical egocentric distance.: distance compression rate =-0.024 × exocentric distance + 0.056. The slope was significant(p = 0.008), indicating the distance compression rate was negatively correlated with the exocentric distance and could be ameliorated at a pace of 2.4% for every 1 m. The adjusted R~2 was 90.7%.We reported the effect of auditory stimulus on the distance compression in VR. Based on our results, we highly recommended presenting the auditory and visual stimuli simultaneously in the time domain and a minimum of 1 m apart in the space domain to ameliorate the distance compression in VR.