Grouping and Emergent Features in Vision

Grouping and Emergent Features in Vision: Toward a Theory of Basic Gestalts

^{James R. Pomerantz , , Mary C. Portillo1}

Department of Psychology, Rice University

^{Received 14 May 2010; revised 17 March 2011; Accepted 27 March 2011. Available online 7 October 2011.}

 

^{Gestalt phenomena are often so powerful that mere demonstrations can confirm their existence, but Gestalts have proven hard to define and measure. Here we outline a theory of basic Gestalts (TBG) that defines Gestalts as emergent features (EFs). The logic relies on discovering wholes that are more discriminable than are the parts from which they are built. These wholes contain EFs that can act as basic features in human vision. As context is added to a visual stimulus, a hierarchy of EFs appears. Starting with a single dot and adding a second yields the first two potential EFs: the proximity (distance) and orientation (angle) between the two dots. A third dot introduces two more potential EFs: symmetry and linearity; a fourth dot produces surroundedness. This hierarchy may extend to collinearity, parallelism, closure, and more. We use the magnitude of Configural Superiority Effects to measure the salience of EFs on a common scale, potentially letting us compare the strengths of various grouping principles. TBG appears promising, with our initial experiments establishing and quantifying at least three basic EFs in human vision.}

^{Keywords: vision; Gestalts; emergent features; configural; wholes}

^{James R. Pomerantz, Department of Psychology, MS 25, P O Box 1892, Houston, TX 77251-1892}

^{1Mary C. Portillo is now at Department of Social Sciences, University of Houston–Downtown.}

 

http://www.sciencedirect.com/science/article/pii/S0096152311601028

 

 

Ervin Poljac, PhD

Laboratory of Experimental Psychology

University of Leuven (K.U. Leuven)

Tiensestraat 102

B-3000 Leuven

Belgium

tel. +32-16-32.61.43 (office)

fax. +32-16-32.60.99

Email: Ervin.Poljac@psy.kuleuven.be

 

Processing of contour closure by baboons (Papio papio).

 

 

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Processing of contour closure by baboons (*Papio papio*).

via Journal of Experimental Psychology: Animal Behavior Processes - Vol 37, Iss 4 door Barbet, Isabelle; Fagot, Joël op 17-10-11

This study investigated the Gestalt law of closure in baboons. Using a computer-controlled self-testing procedure, we trained baboons (Papio papio) to discriminate open versus closed shapes presented on a touch screen with a two-alternative forced choice procedure. Ten baboons (OPEN + group) were trained with the open shapes serving as the positive stimulus (S+), and nine others (CLOSE + group) were trained with the closed shape serving as S+. The OPEN + group obtained higher discrimination performance than the CLOSE + group (Exp 1), but its scores declined when new line segments were added to the stimuli (Exp 2) and after smoothing the end points of the open shapes (Exp 3). The CLOSE + group was less affected by the above manipulations of local stimulus dimension, but its performance was disrupted when the collinearity end points was reduced (Exp 3). Use of a visual search task revealed that the search for an open shape among closed distractors was less attention demanding in baboons than the search for a closed shape among open ones (Exp 4). It is concluded that (1) end lines rather than closeness per se are perceptual primitives for the open versus closed discrimination in baboons, and (2) the relative emphasis on local or configural cues when processing contour closure depends on experiential factors in baboons and is thus subject to interindividual variations. (PsycINFO Database Record (c) 2011 APA, all rights reserved)

 

 

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Arnheim's Gestalt theory of visual balance: Examining the compositional stru...

 

 

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Arnheim's Gestalt theory of visual balance: Examining the compositional structure of art photographs and abstract images. I C McManus, Katharina Stöver, Do Kim

via i-Perception by Pion on 10/19/11

In Art and Visual Perception, Rudolf Arnheim, following on from Denman Ross's A Theory of Pure Design, proposed a Gestalt theory of visual composition. The current paper assesses a physicalist interpretation of Arnheim's theory, calculating an image's centre of mass (CoM). Three types of data are used: a large, representative collection of art photographs of recognised quality; croppings by experts and non-experts of photographs; and Ross and Arnheim's procedure of placing a frame around objects such as Arnheim's two black disks. Compared with control images, the CoM of art photographs was closer to an axis (horizontal, vertical, or diagonal), as was the case for photographic croppings. However, stronger, within-image, paired comparison studies, comparing art photographs with the CoM moved on or off an axis (the 'gamma-ramp study'), or comparing adjacent croppings on or off an axis (the 'spider-web study'), showed no support for the Arnheim–Ross theory. Finally, studies moving a frame around two disks, of different size, greyness, or background, did not support Arnheim's Gestalt theory. Although the detailed results did not support the Arnheim–Ross theory, several significant results were found which clearly require explanation by any adequate theory of the aesthetics of visual composition.

 

 

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Reflections on the Parallellepipeda project. Johan Wagemans

 

 

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Reflections on the Parallellepipeda project. Johan Wagemans

via i-Perception by Pion on 10/19/11

Experimental psycho-aesthetics---the science aimed at understanding the factors that determine aesthetic experience---is reviewed briefly as background to describe the Parallellepipeda project, a cross-over project between artists and scientists in Leuven. In particular, I sketch how it started and developed further, with close interactions between the participating artists and scientists. A few examples of specific research projects are mentioned to illustrate the kind of research questions we address and the methodological approach we have taken. We often found an effect of providing participants with additional information, a difference between novice and expert participants, and a shift with increasing experience with an artwork, in the direction of tolerating more complexity and acquiring more order from it. By establishing more connections between parts of an artwork and more associations to the artwork, it becomes a stronger Gestalt, which is more easily mastered by the viewer and leads to increased appreciation. In the final part of the paper, I extract some general lessons from the project regarding a possible new way of doing psycho-aesthetics research, which is able to solve some of the problems of traditional experimental psycho-aesthetics (eg, trade-off between experimental control and ecological validity).

 

 

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A new kind of science?

Michael Nielsen, whom I mentioned as my principle inspiration behind my recent open science talk, has just published his book on these matters. Here's a review from Nature Physics.

 

 

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A new kind of science?

per Nature Physics - Issue - nature.com science feeds autorius Timo Hannay 11.10.3

A new kind of science?

Nature Physics 7, 742 (2011). doi:10.1038/nphys2109

Author: Timo Hannay

 

 

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workshop: "Neural Coding, Decision-Making & Integration in Time"

"This workshop brings together researchers from fields of computational neuroscience, electrophysiology & behavioral neuroscience to discuss the computational principles underlying neural coding of motor coordination & sensory integration in time with focus on adaptive behavior. Recent research highlights that uncertainty is one of the central problems in cue combination and Bayesian statistics is the systematic way of calculating with uncertainties. Importantly, statistics defines a unified language that can be used both for analyzing why the nervous system works the way it does as well as analyzing how it does so. Within the statistical framework we can formulate the problem of integration of multimodal information over time. The disciplines presented at the workshop include computational neuroscience, Bayesian statistics, psychophysics, neurophysiology, & cognitive science. Central to the format of the proposed workshop is the strong link between computational & empirical neuroscientists. A key aspect of all workshop contributions will be the development of a common theoretical language to be used across behavioral & electrophysiological experiments. The conference is organized as a workshop for 40 selected participants. The central part of the program consists of invited lectures of leading researchers from the fields of computational neuroscience, electrophysiology & behavioral neuroscience; the meeting focuses on creating a common language across these disciplines. The topics chosen, focus on the fundamental problems & limits behind existing theoretical approaches of modeling the neural processing driving human & animal behavior. Selected participants will be invited to present their work in a poster session."

http://www.frontiersin.org/events/Neural_Coding__Decision_Making/1522/All_Events

Fwd: CVNet - Helmholtz! Git yer Helmholtz!

Begin forwarded message:

From: Ben Backus <ben.backus@gmail.com>

Subject: CVNet - Helmholtz! Git yer Helmholtz!

Date: October 7, 2011 1:22:35 GMT+02:00

To: visionlist@visionscience.com, cvnet@mail.ewind.com

Dear Colleagues,

Here is the Treatise on Physiological Optics (1910, English translation 1924), free to download:

http://poseidon.sunyopt.edu/BackusLab/Helmholtz/

Ben Backus
 
--
Benjamin T. Backus, Ph.D.
Associate Professor
Graduate Center for Vision Research
SUNY College of Optometry / SUNY Eye Institute
33 West 42nd St.
New York, NY 10036
Tel. +1-212-938-1541
Fax +1-212-938-5760
http://sunyopt.edu/research/backus