Visual adaptation alters the apparent speed of real-world actions

Abstract

The apparent physical speed of an object in the field of view remains constant despite variations in retinal velocity due to viewing conditions (velocity constancy). For example, people and cars appear to move across the field of view at the same objective speed regardless of distance. In this study a series of experiments investigated the visual processes underpinning judgements of objective speed using an adaptation paradigm and video recordings of natural human locomotion. Viewing a video played in slow-motion for 30 seconds caused participants to perceive subsequently viewed clips played at standard speed as too fast, so playback had to be slowed down in order for it to appear natural; conversely after viewing fast-forward videos for 30 seconds, playback had to be speeded up in order to appear natural. The perceived speed of locomotion shifted towards the speed depicted in the adapting video (‘re-normalisation’). Results were qualitatively different from those obtained in previously reported studies of retinal velocity adaptation. Adapting videos that were scrambled to remove recognizable human figures or coherent motion caused significant, though smaller shifts in apparent locomotion speed, indicating that both low-level and high-level visual properties of the adapting stimulus contributed to the changes in apparent speed.

Low perceptual sensitivity to altered video speed in viewing a soccer match

“…The PSEs were −0.2% (−1.2–0.5%) and 3.0% (1.8–4.2%). These differences may reflect serial dependency effects 7 or speed adaptation 8 , which in the constant-stimuli method depend on trial history. Indeed, PSE was significantly correlated with previous speed exposure in the first experiment (P = 0.014; we recall that these observers also participated in the first experiment, where each group of participants was tested with a different video speed).…”

“…Before applying speed-based compression indiscriminately, however, it will be important to appraise possible side-effects. For example, long-term exposure to high video speeds may lead to perceptual adaptation 8 , and possibly even subtle addiction phenomena 31 . If liberalizing speed is the future of video technologies, we should be prepared for sub-threshold but intensive “kinetic hyper-stimulation”.…”

Speed Biases With Real-Life Video Clips

“…Whether or not this era of compulsory video consumption has indeed changed our visual kinematics habits remains to be ascertained. However, it is remarkable that exposure to video clips of human locomotion played at an altered speed can induce adaptation in locomotion speed perception (Mather et al, 2017 ). The systematic speed underestimation that we have observed in this study may similarly result from adaptation to increased visual hyper-stimulation.…”

Why Do Actions in Slow Motion Appear to Last Longer? On the Effect of Video Speed Information

“…Recently, research has encountered a new context in which specific temporal properties influence subjective judgments, that is to say videos played in altered speeds, especially in slow motion (e.g., Caruso et al., 2016; de'Sperati & Baud Bovy, 2017; Eagleman, 2004; Kashiwakura & Motoyoshi, 2017; Mather & Breivik, 2020; Mather et al., 2017; Nyman et al., 2017; Rossi et al., 2018; Spitz et al., 2017, 2018). Predominantly in sports, this topic has become particularly relevant, partially due to the ongoing debate about whether video replay is helpful to correctly (re-)evaluate critical situations (Spitz et al., 2017) or might even affect evaluations by biasing referees’ decisions due to temporal misperceptions (Caruso et al., 2016; Spitz et al., 2018).…”