Asymmetries in Perception of 3D Orientation

Allan C Dobbins,Jon K Grossmann,Sheng He

doi:10.1371/journal.pone.0009553

Abstract

Visual scene interpretation depends on assumptions based on the statistical regularities of the world. People have some preference for seeing ambiguously oriented objects (Necker cubes) as if tilted down or viewed from above. This bias is a near certainty in the first instant (∼1 s) of viewing and declines over the course of many seconds. In addition, we found that there is modulation of perceived orientation that varies with position—for example objects on the left are more likely to be interpreted as viewed from the right. Therefore there is both a viewed-from-above prior and a scene position-dependent modulation of perceived 3-D orientation. These results are consistent with the idea that ambiguously oriented objects are initially assigned an orientation consistent with our experience of an asymmetric world in which objects most probably sit on surfaces below eye level.

Highlights

Sensory information is commonly fragmentary and ambiguous, yet we are compelled to make rapid interpretations and decisions based on the evidence available
There are many studies demonstrating grouping of ambiguous objects, and others showing that a 3D object that is discrepant in certain ways from its fellows rapidly pops out
As with Attneave’s triangles, Necker cubes joined into complexes along faces or edges may take on interpretations that maximize symmetry of the complex unless a ‘viewed from’ interpretation competes with symmetry [24]

Summary

Introduction

Sensory information is commonly fragmentary and ambiguous, yet we are compelled to make rapid interpretations and decisions based on the evidence available. When visual scenes are experimentally contrived to contain ambiguities, humans use plausible assumptions or priors to inform the perceptual inference process. These priors reflect the statistical regularities experienced by creatures who orient themselves in a characteristic way in a terrestrial environment. One commonly sees an individual cube switch interpretations independently of its neighbors.

Results

Discussion

Materials and Methods