Similarities in Object and Event Segmentation: A Geometric Approach to Event Path Segmentation

Abstract

Events, like objects, can be decomposed into parts. Path, the spatiotemporal trajectory of an object during an event, is the most commonly labeled event feature across the world's languages, provides important social information, and is increasingly central to theories of general event segmentation. However, little is understood about how adults visually segment paths. We apply theories developed for object segmentation to help understand path segmentation. Overall subjects segmented equivalent object shapes and event paths in similar ways following patterns predicted by Singh and Hoffman's (2001) Singh, M. and Hoffman, D. D. 2001. “Parts-based representations of visual shape and implications for visual cognition.”. In From fragments to objects—Segmentation and grouping in vision Edited by: Shipley, T. F. and Kellman, P. J. 401–459. New York, NY: Elsevier Science..  [Google Scholar] geometric analysis of object parts. There were two notable differences between object and event segmentation: (1) event parsing occurred at points of negative curvature minima and positive curvature maxima as opposed to simply negative curvature minima; and (2) event parsing was more frequent and variable than object parsing. Implications of these results for event perception and categorization are discussed.     

Dual-Task Interference in Spatial Reorientation: Linguistic and Nonlinguistic Factors

Abstract

Language has been proposed as a medium that serves to promote spatial orientation through integrating geometric and featural information (Spelke, 2003 Spelke, E. S. 2003. “What makes us smart? Core knowledge and natural language”. In Language in mind: Advances in the study of language and thought, Edited by: Gentner, D. and Goldin-Meadow, S. 277–312. Cambridge, MA: MIT Press..  [Google Scholar]). This proposal has been explored in dual-task experiments where linguistic resources are blocked by verbal shadowing. Although some studies report disruption in using environmental cues for spatial reorientation, findings have not been consistently replicated, and the source of disruption to reorientation by verbal shadowing remains unclear. We examined conditions under which verbal shadowing affects reorientation. Shadowing of meaningful language disrupted healthy adults' use of geometric and featural information to reorient only when task instructions were unclear and when extraneous visual information provided a source of nonlinguistic interference. Reorientation was examined during the shadowing of meaningful prose or nonword syllables and was similar under both concurrent task conditions. These results indicate that language is not necessary for spatial cue integration.     

A Qualitative Calculus for Three-Dimensional Rotations

We have developed a qualitative calculus for three-dimensional directions and rotations. A direction is characterized in terms of the signs of its components relative to an absolute coordinate system. A rotation is characterized in terms of the signs of the components of the associated 3 × 3 rotation matrix.

A system has been implemented that can solve the following problems: 1. Given the signs of direction and rotation matrix P, find the possible signs of the image of under P. Moreover, for each possible sign vector of · P, generate numerical instantiations of and P that yields that result.

2. Given the signs of rotation matrices P and Q, find the possible signs of the composition P · Q. Moreover, for each possible sign matrix for the composition, generate numerical instantiations of P and Q that yield that result.

We have also proved some related complexity and expressivity results. The satisfiability problem for a qualitative rotation constraint network is NP-complete in two dimensions and NP-hard in three dimensions. In three dimensions, any two directions are distinguishable by a qualitative rotation constraint network.     

Correlation between oxygen excess density and critical transition temperature in superconducting Bi-2201, Bi-2212 and Bi-2223

It is suggested that oxygen excess in undoped material of the high temperature superconducting bismuth family creates periodic two-dimensional Cu³⁺-ion patches in the copper–oxygen planes. These nanostructures have a size of square and show a strong linear relationship to their critical transition temperatures T_c.     

Families of periodic solutions in three-dimensional restricted three-body problem

Planar orbits of three-dimensional restricted circular three-body problem are considered as a special case of three-dimensional orbits, and the second-order monodromy matrices M (in coordinate z and velocity v _z ) are calculated for them. Semi-trace s of matrix M determines vertical stability of an orbit. If |s| ≤ 1, then transformation of the subspace (z, v _z ) in the neighborhood of solution for the period is reduced to deformation and a rotation through angle φ, cosφ = s. If the angle ? can be rationally expressed through 2π,φ = 2π·p/q, where p and q are integer, then a planar orbit generates the families of three-dimensional periodic solutions that have a period larger by a factor of q (second kind Poincareé periodic solutions). Directions of continuation in the subspace (z, v _z ) are determined by matrix M. If |s| < 1, we have two new families, while only one exists at resonances 1: 1 (s = 1) and 2: 1 (s = ?1). In the course of motion along the family of three-dimensional periodic solutions, a transition is possible from one family of planar solutions to another one, sometimes previously unknown family of planar solutions.