Symposium Summary

Abstract

Estimating the three-dimensional (3D) structure of the world around us is a central component of our everyday behavior, supporting our decisions, actions and interactions. The problem faced by the brain is classically described in terms of the difficulty of inferring a 3D world from (“ambiguous”) 2D retinal images. The computational challenge of inferring 3D depth from retinal samples requires sophisticated neural machinery that learns to exploit multiple sources of visual information that are diagnostic of depth structure. This sophistication at the input level is demonstrated by our flexibility in perceiving shape under radically different viewing situations. For instance, we can gain a vivid impression of depth from a sparse collection of seemingly random dots, as well as from flat paintings. Adding to the complexity, humans exploit depth signals for a range of different behaviors, meaning that the input complexity is compounded by multiple functional outputs. Together, this poses a significant challenge when seeking to investigate empirically the sequence of computations that enable 3D vision. This symposium brings together speakers from different perspectives to outline progress in understanding 3D vision. Fleming will start, addressing the question of “What is the information?”, using computational analysis of 3D shape to highlight basic principles that produce depth signatures from a range of cues. Todd and Glennerster will both consider the question of “How is this information represented?”, discussing different types of representational schemes and data structures. Welchman, Orban and Janssen will focus on the question of “How is it implemented in cortex?”. Welchman will discuss human fMRI studies that integrate psychophysics with concurrent measures of brain activity. Orban will review fMRI evidence for spatial correspondence in the processing of different depth cues in the human and monkey brain. Janssen will summarize results from single cell electrophysiology, highlighting the similarities and differences between the processing of 3D shape at the extreme ends of the dorsal and ventral pathways. Finally, Glennerster, Orban and Janssen will all address the question of how depth processing is affected by task. The symposium should attract a wide range of VSS participants, as the topic is a core area of vision science and is enjoying a wave of public enthusiasm with the revival of stereoscopic entertainment formats. Further, the goal of the session in linking computational approaches to behavior to neural implementation is one that is scientifically attractive.