The construction of perceptual grouping displays using GERT

Demeyer, Maarten; Machilsen, Bart

doi:10.3758/s13428-011-0167-8

Cited by 39 publications

(29 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This element was generated by multiplying a cosine luminance grating with an elliptic Gaussian with a standard deviation of 2.5 pixels in one direction and a standard deviation of 70 pixels in the other direction resulting in a continuous contour covering the diagonal of the stimulus display. All stimuli were generated with the Grouping Elements Rendering Toolbox (GERT; Demeyer & Machilsen, 2012) for MATLAB (Mathworks) and had an aspect ratio of 1:1 (4.41°Â 4.41°of visual angle; 1 cm % 0.82°of visual angle). Primes were presented at the center of the screen, targets were presented offset by 0.88°above or below the center.…”

Section: Apparatus and Stimulimentioning

confidence: 99%

Response priming evidence for feedforward processing of snake contours but not of ladder contours and textures

Schmidt

Vancleef

2016

Vision Research

View full text Add to dashboard Cite

In contour integration, increased difficulty in detection and shape discrimination of a chain of parallel elements (a ladder contour) compared to collinear elements (a snake contour) suggests more extensive processing of ladders than of snakes. In addition, conceptual similarities between ladders and textures - which also involve grouping of parallel elements - raises the question whether ladder and texture processing requires feedback from higher visual areas while snakes are processed in a fast feedforward sweep. We tested this in a response priming paradigm, where participants responded as quickly and accurately as possible to the orientation of a diagonal contour in a Gabor array (target). The diagonal was defined either by a snake, ladder, texture, or a continuous line. The target was preceded with varying stimulus onset asynchrony (SOA) by a prime that was either a snake, ladder, or texture, and was consistent or inconsistent to the response demands of the target. Resulting priming effects clearly distinguished between processing of snakes, ladders, and textures. Effects generally increased with SOA but were stronger for snakes and textures compared to ladders. Importantly, only priming effects for snakes were fully present already in the fastest response times, in accordance with a simple feedforward processing model. We conclude that snakes, ladders, and textures do not share similar processing characteristics, with snakes exhibiting a pronounced processing advantage.

show abstract

Section: Apparatus and Stimulimentioning

confidence: 99%

Response priming evidence for feedforward processing of snake contours but not of ladder contours and textures

Schmidt

Vancleef

2016

Vision Research

View full text Add to dashboard Cite

show abstract

“…Therefore the relaxation needs to be applied to the first line of Equation (2), and not directly to its solution d hex . This is what is done in Equation (3). For large values of N ,…”

Section: Placing the Alignmentmentioning

confidence: 86%

“…This quantity is defined by Equation (7) as the maximum number 3 It may seem more intuitive to simply relax the minimal distance by setting…”

Section: Placing the Alignmentmentioning

confidence: 99%

“…Following [3,17], we check for density cues by comparing the area of the aligned points' Voronoi cells (also called target cells) to those of the background points (also called background cells); see Figure 6. If the areas of the target cells are significantly different from those of the background cells, then we suspect that a density cue may exist in the stimulus.…”

Section: Checking For Density Cuesmentioning

confidence: 99%

See 1 more Smart Citation

Generation and Detection of Alignments in Gabor Patterns

Blusseau¹,

Gioi²

2016

Image Processing on Line

View full text Add to dashboard Cite

This paper presents a method to be used in psychophysical experiments to compare directly visual perception to an a contrario algorithm, on a straight patterns detection task. The method is composed of two parts. The first part consists in building a stimulus, namely an array of oriented elements, in which an alignment is present with variable salience. The second part focuses on a detection algorithm, based on the a contrario theory, which is designed to predict which alignment will be considered as the most salient in a given stimulus. Source CodeThe source code associated to this manuscript (written in Matlab) and an online demo are available from the web page of this article 1 .

show abstract

“…We created Gabor contours using Matlab and a precursor of the Grouping Elements Rendering Toolbox [32]. We first generated contours in pairs, each contour defined by adding four radial frequency components (sinusoids with wavelengths of π, 2π/3, π/2, and 2π/5, respectively) to a fixed radius r. The phase offset was randomized for all sinusoid components separately, and their amplitudes drawn at random from a continuous uniform distribution between r/12 and r/6.…”

Section: Initial Stimulus Generationmentioning

confidence: 99%

Peripheral Contour Grouping and Saccade Targeting: The Role of Mirror Symmetry

Sassi¹,

Demeyer²,

Wagemans³

2014

Symmetry

Self Cite

View full text Add to dashboard Cite

Abstract:Integrating shape contours in the visual periphery is vital to our ability to locate objects and thus make targeted saccadic eye movements to efficiently explore our surroundings. We tested whether global shape symmetry facilitates peripheral contour integration and saccade targeting in three experiments, in which observers responded to a successful peripheral contour detection by making a saccade towards the target shape. The target contours were horizontally (Experiment 1) or vertically (Experiments 2 and 3) mirror symmetric. Observers responded by making a horizontal (Experiments 1 and 2) or vertical (Experiment 3) eye movement. Based on an analysis of the saccadic latency and accuracy, we conclude that the figure-ground cue of global mirror symmetry in the periphery has little effect on contour integration or on the speed and precision with which saccades are targeted towards objects. The role of mirror symmetry may be more apparent under natural viewing conditions with multiple objects competing for attention, where symmetric regions in the visual field can pre-attentively signal the presence of objects, and thus attract eye movements.

show abstract

The construction of perceptual grouping displays using GERT

Cited by 39 publications

References 57 publications

Response priming evidence for feedforward processing of snake contours but not of ladder contours and textures

Response priming evidence for feedforward processing of snake contours but not of ladder contours and textures

Generation and Detection of Alignments in Gabor Patterns

Peripheral Contour Grouping and Saccade Targeting: The Role of Mirror Symmetry

Contact Info

Product

Resources

About