Insect perception of illusory contours

1992 ◽  
Vol 337 (1279) ◽  
pp. 59-64 ◽  
Keyword(s):  
Human Visual System ◽  
Illusory Contour ◽  
Optic Lobe ◽  
Insect Vision ◽  
Local Contrast ◽  
Fault Line ◽  
Illusory Contours ◽  
Striped Pattern ◽  
Processing Power ◽  
As If

The human visual system sees an illusory contour where there is a fault line across a regular striped pattern. We demonstrate that bees respond as if they see the same illusory contour. There is also a type of neuron in the lobula of the dragonfly optic lobe which responds directionally to motion of the illusory contour as if to an edge or line. Apparently insects have a mechanism that sees illusory contours and therefore assists in the demarcation of edges and objects at places where local contrast falls to zero at an edge, or where one textured object partially obscures another. These results suggest that insect vision, although spatially crude and low in processing power, sees separate objects by similar mechanisms to our own.

scholarly journals Induction of Kanizsa contours requires awareness of the inducing context

2016 ◽  
Author(s):  
Theodora Banica ◽  
Dietrich Samuel Schwarzkopf
Keyword(s):  
Human Visual System ◽  
Illusory Contour ◽  
Visual Masking ◽  
Spatial Localization ◽  
Localization Task ◽  
Illusory Contours ◽  
Perceptual Integration ◽  
Complex Scenes ◽  
Recurrent Process ◽  
Rule Out

AbstractIt remains unknown to what extent the human visual system interprets information about complex scenes without conscious analysis. Here we used visual masking techniques to assess whether illusory contours (Kanizsa shapes) are perceived when the inducing context creating this illusion does not reach awareness. In the first experiment we tested perception directly by having participants discriminate the orientation of an illusory contour. In the second experiment, we exploited the fact that the presence of an illusory contour enhances performance on a spatial localization task. Moreover, in the latter experiment we also used a different masking method to rule out the effect of stimulus duration. Our results suggest that participants do not perceive illusory contours when they are unaware of the inducing context. This is consistent with theories of a multistage, recurrent process of perceptual integration. Our findings thus challenge some reports, including those from neurophysiological experiments in anaesthetized animals. Furthermore, we discuss the importance to test the presence of the phenomenal percept directly with appropriate methods.

An Illusory Contour Can Facilitate Visually Induced Self-Motion Perception

2018 ◽  
Vol 31 (8) ◽  
pp. 715-727
Author(s):  
Shinji Nakamura ◽  
Shin’ya Takahashi
Keyword(s):  
Motion Perception ◽  
Illusory Contour ◽  
Uniform Motion ◽  
Horizontal Line ◽  
Illusory Contours ◽  
End Points ◽  
Line Segments ◽  
Illusory Perception ◽  
Vertically Aligned ◽  
Self Motion

Abstract Uniform motion of a visual stimulus induces an illusory perception of the observer’s self-body moving in the opposite direction (vection). The present study investigated whether vertical illusory contours can affect horizontal translational vection using abutting-line stimulus. The stimulus consisted of a number of horizontal line segments that moved horizontally at a constant speed. A group of vertically aligned segments created a ‘striped column’, while line segments in adjoining columns were shifted vertically to make a slight gap between them. In the illusory contour condition, the end points of the segments within the column were horizontally aligned to generate vertical illusory contours. In the condition with no illusory contour, these end points were not aligned within the column so that the illusory contour was not perceived. In the current study, 11 participants performed this experiment, and it was shown that stronger vection was induced in the illusory contour condition than in the condition with no illusory contour. The results of the current experiment provide novel evidence suggesting that non-luminance-defined visual features have a facilitative effect on visual self-motion perception.

Parallelism and the Perception of Illusory Contours

Perception ◽  
1993 ◽  
Vol 22 (5) ◽  
pp. 589-595 ◽  
Author(s):  
Marc K Albert
Keyword(s):  
Illusory Contour ◽  
Illusory Contours ◽  
Gestalt Principles ◽  
Contour Strength

The role of symmetry in the perception of illusory contours has been a subject of controversy ever since Kanizsa proposed his theory of illusory contours based on Gestalt principles. Today it is widely agreed that illusory contours do not necessarily occur more readily with inducers that can be ‘amodally’ completed to symmetrical objects than with inducers that cannot. But the question of whether symmetrical inducers produce weaker illusory contours than do unsymmetrical ones is still controversial. A novel determinant of illusory contour strength, parallelism, is proposed. Experiments are reported which indicate that illusory contours induced by ‘blobs’ which have boundaries that are nearby and parallel to the illusory contour are weaker than illusory contours induced by blobs that do not have this property. It is suggested that the display that has been most widely used by researchers to support their claims for a weakening of illusory contours with symmetrical inducers is weak primarily because of parallelism.

Neural Mechanisms in Boundary Grouping, Illusory Contour Generation, and Spatial Tuning of Receptive Field Selectivity

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 108-108 ◽  
Author(s):  
H Neumann ◽  
P Mössner
Keyword(s):  
Illusory Contour ◽  
Spatial Arrangement ◽  
Orientation Selectivity ◽  
Fine Tuning ◽  
Local Contrast ◽  
Resonance Theory ◽  
Spatial Coupling ◽  
Noisy Input ◽  
Signal Features ◽  
Visual Cortical

A model for cortical boundary detection and contour grouping at visual cortical areas V1 and V2 is presented. The functional organisation of the model architecture is based on principles of adaptive resonance theory (Grossberg, 1980 Psychological Review87 1 – 51). The primary visual areas are connected in a bidirectional scheme of feedforward and feedback projections. Signal features are initially measured by orientation-sensitive neurons at the simple and complex cell level. These measurements undergo local competitive processing and subsequent nonlinear bipole integration of coherent activity (von der Heydt and Peterhans, 1988 Journal of Neuroscience9 1731 – 1748). The integration is based on an antagonistic interaction in position and orientation space utilising spatial coupling and compatibility functions for the evaluation of coherent activity distributions. This step can therefore be interpreted as implementing a process of matching neural codes of most-likely contour outlines against the noisy input distribution of local contrast measurements. The result of the integration stage is fed back to the first competitive stages to enhance compatible activations via multiplicative gating. The net effect produces grouping and illusory contour completion. In particular, the results of model simulations demonstrate that (i) the orientation selectivity of V1 cells is sharpened depending on the spatial arrangement and visual context, (ii) orientation-selective contrast measurements are enhanced at boundaries of spatially homogeneous stimulus arrangements and suppressed in the interiors, (iii) oriented cells at model V2 stage only respond to curvilinear input arrangements of activity at both branches of bipole cells, and (iv) model V2 cells show fine tuning for orientation selectivity and generate subjective contours to bridge gaps in arrangements of oriented contrast.

Cue-dependent deficits in grating orientation discrimination after V4 lesions in macaques

1996 ◽  
Vol 13 (3) ◽  
pp. 529-538 ◽  
Author(s):  
Peter De Weerd ◽  
Robert Desimone ◽  
Leslie G. Ungerleider
Keyword(s):  
Visual Field ◽  
Normal Control ◽  
Illusory Contour ◽  
Visual Area ◽  
Orientation Discrimination ◽  
Fixation Target ◽  
Illusory Contours ◽  
Pattern Vision ◽  
Area V4

AbstractTo examine the role of visual area V4 in pattern vision, we tested two monkeys with lesions of V4 on tasks that required them to discriminate the orientation of contours defined by several different cues. The cues used to separate the contours from their background included luminance, color, motion, and texture, as well as phase-shifted abutting gratings that created an “illusory” contour. The monkeys were trained to maintain fixation on a fixation target while discriminating extrafoveal stimuli, which were located in either a normal control quadrant of the visual field or in a quadrant affected by a lesion of area V4 in one hemisphere. Comparing performance in the two quadrants, we found significant deficits for contours defined by texture and for the illusory contour, but smaller or no deficits for motion-, color-, and luminance-defined contours. The data suggest a specific role of V4 in the perception of illusory contours and contours defined by texture.

The Multiple Determination of Illusory Contours: 2. An Empirical Investigation

Perception ◽  
1983 ◽  
Vol 12 (3) ◽  
pp. 293-303 ◽  
Author(s):  
Diane F Halpern ◽  
Billie Salzman ◽  
Wayne Harrison ◽  
Keith Widaman
Keyword(s):  
Illusory Contour ◽  
Factor Model ◽  
Illusory Contours ◽  
Contour Perception ◽  
Confirmatory Factor ◽  
Linear Effects ◽  
Explained Variance ◽  
Taxonomic Approach ◽  
Contour Strength

Judgments of contour strength or saliency for twenty-four illusory-contour configurations were subjected to a confirmatory factor analysis. A four-factor model that posited the involvement of simultaneous contrast, linear effects (assimilation and dissimilation), depth/completion cues, and feature analyzers accounted for a substantial proportion of the variance in judgments of illusory-contour strength. The hierarchical addition of a fifth factor, diffuse illusory contours, significantly improved the overall fit of the model, but added little to the proportion of explained variance. The taxonomic approach adopted provides support for a multiprocess model of illusory-contour perception.

scholarly journals Computational experiment of error diffusion dithering for depth reduction in images

2020 ◽  
Vol 1 (2) ◽  
pp. 9-13
Author(s):  
Leonardo Rezende Costa
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Computational Experiment ◽  
White Paper ◽  
Error Diffusion ◽  
Visual Effect ◽  
Black And White ◽  
Halftone Images ◽  
Depth Reduction ◽  
As If

The halftone technique is a process that employs patterns formed by black and white dots to reduce the number of gray levels in an image. Due to the tendency of the human visual system to soften the distinction between points with different shades, the patterns of black and white dots produce a visual effect as if the image were composed of shades of gray and dark. This technique is quite old and is widely used in printing images in newspapers and magazines, in which only black (ink) and white (paper) levels are needed. There are several methods for generating halftone images. In this article we explore dithering with error diffusion and an analysis of different halftone techniques is presented using error diffusion to change the depth of the image. The results showed that the depth of the image changes 1/8 per channel, this halftone technique can be used to reduce an image weight, losing information but achieving good results, depending on the context. ontext.

Improbable Illusory Contours

2017 ◽  
Author(s):  
Barton L. Anderson
Keyword(s):  
Perceptual Organization ◽  
Adaptive Response ◽  
Illusory Contour ◽  
Visual Illusion ◽  
Missing Information ◽  
Illusory Contours ◽  
New Class ◽  
Testing Ground ◽  
Rational Inference

Illusory contours are one of the most widely studied kinds of visual illusion. Illusory contours are often understood as an adaptive response to filling-in missing information created from conditions of camouflage. This chapter describes a new class of very vivid illusory contours that appear impossible to understand as forms of rational inference. It presents a set of illusory contours that emerge in conditions for which there is no missing information or need for their synthesis. It argues that such contours provide a valuable testing ground for both specific theories of illusory contour formation, and general theories of perceptual organization. Videos made specifically for this chapter help illustrate the concepts discussed.

scholarly journals Why Do Line Drawings Work? A Realism Hypothesis

Perception ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 439-451 ◽  
Author(s):  
Aaron Hertzmann
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Line Drawing ◽  
Natural World ◽  
Human Observer ◽  
Object Identity ◽  
Line Drawings ◽  
3D Shape ◽  
Realistic Images ◽  
As If

Why is it that we can recognize object identity and 3D shape from line drawings, even though they do not exist in the natural world? This article hypothesizes that the human visual system perceives line drawings as if they were approximately realistic images. Moreover, the techniques of line drawing are chosen to accurately convey shape to a human observer. Several implications and variants of this hypothesis are explored.

How a Brain Sees: Neural Mechanisms

2021 ◽  
pp. 122-183
Author(s):  
Stephen Grossberg
Keyword(s):  
Illusory Contour ◽  
Local Contrast ◽  
Simple Complex ◽  
3D Vision ◽  
Color Spreading ◽  
Surface Filling ◽  
Contour Strength ◽  
Neon Color Spreading ◽  
Glass Patterns ◽  
Boundary Completion

Multiple paradoxical visual percepts are explained using boundary completion and surface filling-in properties, including discounting the illuminant; brightness constancy, contrast, and assimilation; the Craik-O’Brien-Cornsweet Effect; and Glass patterns. Boundaries act as both generators and barriers to filling-in using specific cooperative and competitive interactions. Oriented local contrast detectors, like cortical simple cells, create uncertainties that are resolved using networks of simple, complex, and hypercomplex cells, leading to unexpected insights such as why Roman typeface letter fonts use serifs. Further uncertainties are resolved by interactions with bipole grouping cells. These simple-complex-hypercomplex-bipole networks form a double filter and grouping network that provides unified explanations of texture segregation, hyperacuity, and illusory contour strength. Discounting the illuminant suppresses illumination contaminants so that feature contours can hierarchically induce surface filling-in. These three hierarchical resolutions of uncertainty explain neon color spreading. Why groupings do not penetrate occluding objects is explained, as are percepts of DaVinci stereopsis, the Koffka-Benussi and Kanizsa-Minguzzi rings, and pictures of graffiti artists and Mooney faces. The property of analog coherence is achieved by laminar neocortical circuits. Variations of a shared canonical laminar circuit have explained data about vision, speech, and cognition. The FACADE theory of 3D vision and figure-ground separation explains much more data than a Bayesian model can. The same cortical process that assures consistency of boundary and surface percepts, despite their complementary laws, also explains how figure-ground separation is triggered. It is also explained how cortical areas V2 and V4 regulate seeing and recognition without forcing all occluders to look transparent.

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