Perception of Human Interaction Based on Motion Trajectories: From Aerial Videos to Decontextualized Animations

• Published in: Topics in cognitive science Vol. 10; no. 1; pp. 225 - 241
• Main Authors: Shu, Tianmin, Peng, Yujia, Fan, Lifeng, Lu, Hongjing, Zhu, Song‐Chun
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.01.2018
• Subjects: Action understanding; Decontextualized animation; Hierarchical model; Motion; Social interaction; Motion; Hierarchical model; Action understanding; Social interaction; Decontextualized animation
• ISSN: 1756-8757; 1756-8765
• DOI: 10.1111/tops.12313

People are adept at perceiving interactions from movements of simple shapes, but the underlying mechanism remains unknown. Previous studies have often used object movements defined by experimenters. The present study used aerial videos recorded by drones in a real‐life environment to generate decontextualized motion stimuli. Motion trajectories of displayed elements were the only visual input. We measured human judgments of interactiveness between two moving elements and the dynamic change in such judgments over time. A hierarchical model was developed to account for human performance in this task. The model represents interactivity using latent variables and learns the distribution of critical movement features that signal potential interactivity. The model provides a good fit to human judgments and can also be generalized to the original Heider–Simmel animations (1944). The model can also synthesize decontextualized animations with a controlled degree of interactiveness, providing a viable tool for studying animacy and social perception. Drones collected aerial videos of human interaction that were decontextualized to depict two people as dots of different colors. These stimuli, and more standard ones, were used to examine human perception of social interactions. A 3‐layer, Bayesian Hierarchical models fit human judgments of interactiveness well and suggests mechanisms underlying our understanding of purposeful, human interactions.