The geometry of visual perception: Retinotopic and nonretinotopic representations in the human visual system

Michael Herzog
2010
Journal paper

Geometry is closely linked to visual perception; yet, very little is known about the geometry of visual processing beyond early retinotopic organization. We present a variety of perceptual phenomena showing that a retinotopic representation is neither sufficient nor necessary to support form perception. We discuss the popular Bobject files-concept as a candidate for nonretinotopic representations and, based on its shortcomings, suggest future directions for research using local manifold representations. We suggest that these manifolds are created by the emergence of dynamic reference-frames that result from motion segmentation. We also suggest that the metric of these manifolds is based on relative motion vectors.

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related concepts

Related publications

Michael Herzog
2010
Journal paper

Abstract

Official source

https://infoscience.epfl.ch/record/162422?ln=en

About this result

Related concepts (8)

Related concepts

Related publications (10)

Related publications

Visual perception

Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision),

Visual system

The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) wh

Visual processing

Visual processing is a term that is used to refer to the brain's ability to use and interpret visual information from the world around us. The process of converting light energy into a meaningful imag

Perceptual grouping induces non-retinotopic feature attribution in human vision

Michael Herzog, Thomas Otto

The human visual system computes features of moving objects with high precision despite the fact that these features can change or blend into each other in the retinotopic image. Very little is known about how the human brain accomplishes this complex feat. Using a Ternus-Pikler display, introduced by Gestalt psychologists about a century ago, we show that human observers can perceive features of moving objects at locations these features are not present. More importantly, our results indicate that these non-retinotopic feature attributions are not errors caused by the limitations of the perceptual system but follow rules of perceptual grouping. From a computational perspective, our data imply sophisticated real-time transformations of retinotopic relations in the visual cortex. Our results suggest that the human motion and form systems interact with each other to remap the retinotopic projection of the physical space in order to maintain the identity of moving objects in the perceptual space.

Elsevier2006

A New Approach to Non-Retinotopic Processing

Marco Boi

At every moment, the image the world projects on our eyes undergoes rapid and dramatic changes due to the eye movements and to the motion of the objects. Surprisingly, we are not aware of these changes, experiencing the world as stable and constant. This apparent contradiction suggests that our visual system uses non-retinotopic representations of the objects in the visual scene to create a stable percept of the world. Which visual mechanisms make use of non-retinotopic representations is a question of fundamental importance in neuroscience. The study of visual stability and non-retinotopic processing has classically focused on the problem of eye movements and has been studied in this context. We have proposed a new view on the problem of non-retinotopic processing that allows explaining how a stable percept of the world is created both across the movements of the eyes and objects. Based on this view, we devised an experimental paradigm that allows testing whether a given mechanism makes use of non-retinotopic representations and we applied it to several different visual processes. Our results suggest that non-retinotopic representations are used in higher-level visual processes whereas low-level mechanisms seem to operate on retinotopic representations.

EPFL2010

Retinotopy of visual masking and non-retinotopic perception during masking

Michael Herzog

Due to the movements of the observer and those of objects in the environment, retinotopic representations are highly unstable during ecological viewing conditions. The phenomenal stability of our perception suggests that retinotopic representations are transformed into non-retinotopic representations. It remains to show, however, which visual processes operate under retinotopic representations and which ones operate under non-retinotopic representations. Visual masking refers to the reduced visibility of one stimulus, called the target, due to the presence of a second stimulus, called the mask. Masking has been used extensively to study the dynamic aspects of visual perception. Previous studies using Saccadic Stimulus Presentation Paradigm (SSPP) suggested both retinotopic and non-retinotopic bases for visual masking. In order to understand how the visual system deals with retinotopic changes induced by moving targets, we investigated the retinotopy of visual masking and the fate of masked targets under conditions that do not involve eye movements. We have developed a series of experiments based on a radial Ternus-Pikler display. In this paradigm, the perceived Ternus-Pikler motion is used as a non-retinotopic reference frame to pit retinotopic against non-retinotopic visual masking hypothesis. Our results indicate that both metacontrast and structure masking are retinotopic. We also show that, under conditions that allow observers to read-out effectively non-retinotopic feature attribution, the target becomes visible at a destination different from its retinotopic/spatiotopic location. We discuss the implications of our findings within the context of ecological vision and dynamic form perception.

Springer2015