title: Seeing liquids from visual motion.
abstract: Most research on human visual recognition focuses on solid objects, whose identity is defined primarily by shape. In daily life, however, we often encounter materials that have no specific form, including liquids whose shape changes dynamically over time. Here we show that human observers can recognize liquids and their viscosities solely from image motion information. Using a two-dimensional array of noise patches, we presented observers with motion vector fields derived from diverse computer rendered scenes of liquid flow. Our observers perceived liquid-like materials in the noise-based motion fields, and could judge the simulated viscosity with surprising accuracy, given total absence of non-motion information including form. We find that the critical feature for apparent liquid viscosity is local motion speed, whereas for the impression of liquidness, image statistics related to spatial smoothness-including the mean discrete Laplacian of motion vectors-is important. Our results show the brain exploits a wide range of motion statistics to identify non-solid materials.
authors.affiliation: NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, 3-1, Morinosato Wakamiya, Atsugi 243-0198, Kanagawa, Japan. Electronic address: kawabe.takahiro@lab.ntt.co.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kawabe
authors.affiliation: NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, 3-1, Morinosato Wakamiya, Atsugi 243-0198, Kanagawa, Japan.
authors.forename: Kazushi
authors.initials: K
authors.lastname: Maruya
authors.affiliation: Department of Experimental Psychology, University of Gießen, FB06 - Psychologie, Otto-Behaghel-Str. 10/F2-338, 53594 Gießen, Germany.
authors.forename: Roland W
authors.initials: RW
authors.lastname: Fleming
authors.affiliation: NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, 3-1, Morinosato Wakamiya, Atsugi 243-0198, Kanagawa, Japan.
authors.forename: Shin'ya
authors.initials: S
authors.lastname: Nishida
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D057849:Optic Flow / Q000502:physiology; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation; D021641:Recognition, Psychology; D014783:Viscosity; D014785:Vision, Ocular / Q000502:physiology*
keywords: Liquid impression; Material perception; Viscosity; Visual motion