Rossi Federica, Montanaro Elisa, de'Sperati Claudio
Laboratory of Action, Perception and Cognition, Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy.
Department of Neuroscience Rita Levi Montalcini, University of Turin, Turin, Italy.
Front Integr Neurosci. 2018 Mar 16;12:11. doi: 10.3389/fnint.2018.00011. eCollection 2018.
We live almost literally immersed in an artificial visual world, especially motion pictures. In this exploratory study, we asked whether the best speed for reproducing a video is its original, shooting speed. By using adjustment and double staircase methods, we examined speed biases in viewing real-life video clips in three experiments, and assessed their robustness by manipulating visual and auditory factors. With the tested stimuli (short clips of human motion, mixed human-physical motion, physical motion and ego-motion), speed underestimation was the rule rather than the exception, although it depended largely on clip content, ranging on average from 2% (ego-motion) to 32% (physical motion). Manipulating display size or adding arbitrary soundtracks did not modify these speed biases. Estimated speed was not correlated with estimated duration of these same video clips. These results indicate that the sense of speed for real-life video clips can be systematically biased, independently of the impression of elapsed time. Measuring subjective visual may integrate traditional methods that assess time perception: speed biases may be exploited to develop a simple, objective test of reality flow, to be used for example in clinical and developmental contexts. From the perspective of video media, measuring speed biases may help to optimize video reproduction speed and validate "natural" video compression techniques based on sub-threshold temporal squeezing.
我们几乎实实在在地生活在一个人造视觉世界中，尤其是电影世界。在这项探索性研究中，我们探讨了重现视频的最佳速度是否就是其原始拍摄速度。通过使用调整法和双阶梯法，我们在三个实验中研究了观看真实生活视频片段时的速度偏差，并通过操纵视觉和听觉因素评估了这些偏差的稳健性。对于所测试的刺激（人类运动短片、人类与物体混合运动短片、物体运动短片和自我运动短片），速度低估是普遍现象而非个别情况，尽管这在很大程度上取决于片段内容，平均范围从2%（自我运动）到32%（物体运动）。操纵显示尺寸或添加任意的音轨并不会改变这些速度偏差。估计速度与这些相同视频片段的估计时长并无关联。这些结果表明，真实生活视频片段的速度感可能会出现系统性偏差，且与对流逝时间的感知无关。测量主观视觉速度可能会整合评估时间感知的传统方法：速度偏差可被用于开发一种简单、客观的现实流动测试，例如可用于临床和发育研究环境。从视频媒体的角度来看，测量速度偏差可能有助于优化视频重现速度，并验证基于亚阈值时间压缩的“自然”视频压缩技术。
