While decades of research have deepened our understanding of time perception, the perception of (manipulated) video speed remains a relatively new and underexplored topic. Fueled by technological advances, the use of slow motion or time lapse, are now common tools in daily life, offering the option for detailed video analysis. Yet, recent research highlights potential biases in perception and low sensitivity to altered video speed.
To investigate to which extent humans can perceive altered video speeds and how different video speeds influence duration experience, we conducted a series of experiments where participants viewed short video clips at different video speeds. Our results demonstrate systematic biases: overestimation of video speed during slow motion and underestimation of video speed when watching time lapse versions, intensifying with greater deviations from the original speed. Moreover, duration estimations systematically varied depending on video speed, as slow motion videos were perceived to last shorter than videos at normal or accelerated speeds, suggesting a recalibration mechanism occurring already during viewing. Both effects seem to result in an erroneous “mental backwards calculation” in the attempt to infer the true duration of an event. This results in a distorted impression about the time that had actually elapsed, which, in turn, typically influences, for example, how intentional an action is perceived to be. These biases have broader implications for time perception in general and for applied fields such as law and sports, where judgments are often based on modern video analysis and hence require careful consideration.