Dynamic point-light cloths generate rich percepts beyond biology

Visual processing seems specialized for perceiving other agents,^1,2 as in biological motion perception: displays of surprisingly few moving dots ("point-light walkers"; PLWs) give rise to rich percepts of locomoting agents.³ Despite hundreds of experiments over decades of research,^4,5,6 a foundational question remains unanswered: how specific are such phenomena to biological motion? Addressing this question has been historically challenging, largely due to the absence of non-biological comparison stimuli-since the translation or rotation of rigid objects (as in "structure-from-motion" displays^7,8) lacks the rich relative motion of the points that is characteristic of PLWs. Here, to fill this gap, we introduce the perception of rich behavior from dynamic point-light cloths (PLCs)-as when a ribbon (or a sheet on a clothesline) is waving in the wind. Across 13 preregistered experiments, while focusing on several of the most foundational properties of biological motion, we found broad similarities between PLWs and PLCs-in terms of both experimental results and phenomenological demonstrations: percepts from PLCs (1) arise spontaneously and robustly, even in dynamic noise; (2) depend on cohesive relative motion, since they disappear both in static displays and in dynamic displays with spatially scrambled points; (3) do not require consistent local motion, since they persist in "limited-lifetime" displays; and (4) extend to rich secondary properties such as a fabric's stiffness. These results collectively demonstrate that, even beyond agents and biology, the visual system extracts rich structure from surprisingly limited input.