Aesthetic speed preferences when viewing dance synchronize to a 'natural' pace of human movement.

The human body in motion is typically in service of everyday tasks - but it can also be aesthetically pleasing, as in dance. Is there a common property underlying how we perceive and appreciate human motion in both everyday and aesthetic contexts? Here we focus on one of the most basic features of motion: the speed at which it unfolds. In a 'set-the-pace' task, people adjusted the playback speed of a broad range of videos to what was "maximally pleasing" to them. This method revealed three distinct correlates of aesthetic speed preferences across multiple experiments and replications. First, when looking across genres, aesthetically pleasing speeds converged at a sweet spot of amount of motion, computed by a measure of optical flow: faster dances (e.g., Bollywood) were consistently slowed down, and slower dances (e.g., classical ballet or Chinese folk) were sped up. Second, aesthetic speed preferences were domain-specific: responses for dance videos were predicted only by responses for videos involving human (e.g., sports), but not non-human (e.g., object or animal) motion. Finally, what's specific to aesthetic speed preferences for human motion? Separate sets of observers adjusted playback speeds to "where the dancer was maximally expressive" and to "the pace at which people naturally move". Aesthetic speed preferences were highly correlated with both measures, but only "natural" pace ratings ultimately predicted unique variance above and beyond other factors. Thus, aesthetic speed preferences in dance may be tuned not just to the outward expressiveness of the dancer, but also to what we synchronize to, i.e., the pace at which we encounter human motion in everyday life.