A pushing stick or a pulled rubber band: Material perception reverses the causal arrow in agent–patient dynamics.

Abstract

People effortlessly recognize objects of various materials and predict their behavior from visual information. However, research on causal perception has largely underexplored dynamic interactions involving nonrigid objects, often treating spatiotemporal causality as independent of object properties. To address this gap, we introduce a novel causal perception phenomenon in which speed profiles alone evoke the perception of elastic, nonrigid motion in interactions between simple geometric figures, ultimately shaping causal perception. Using an ambiguous-motion stimulus involving a separation event, we show that a line segment elongating with a disc at its end before separating can be interpreted in two distinct ways-as a rigid stick pushing a disc or as a disc pulling an elastic band. Across four experiments, deceleration before separation followed by rapid postseparation motion consistently biased perception toward the elastic band interpretation, demonstrating the critical role of kinematic regularities in shaping both causal and material perception. Four follow-up experiments using a pause-detection task revealed sensitivity to motion dynamics inconsistent with a stretched elastic band, even when causal and material perception was entirely task-irrelevant, further indicating the perceptual nature of this phenomenon. These findings illustrate how subtle kinematic patterns can simultaneously reverse perceived force dynamics and causal roles, accompanied by corresponding shifts in material perception, contributing to a unified framework for material and causal perception. Ultimately, this work provides new insights into how the visual system uses kinematic information to assign causal agents and patients in dynamic interactions. (PsycInfo Database Record (c) 2026 APA, all rights reserved).