scholarly journals Predator perception and the interrelation between different forms of protective coloration

2007 ◽  
Vol 274 (1617) ◽  
pp. 1457-1464 ◽  
Author(s):  
Martin Stevens
Keyword(s):  
Visual Perception ◽  
Warning Coloration ◽  
Protective Coloration ◽  
Disruptive Coloration ◽  
Risk Of Predation ◽  
Motion Camouflage ◽  
Future Work

Animals possess a range of defensive markings to reduce the risk of predation, including warning colours, camouflage, eyespots and mimicry. These different strategies are frequently considered independently, and with little regard towards predator vision, even though they may be linked in various ways and can be fully understood only in terms of predator perception. For example, camouflage and warning coloration need not be mutually exclusive, and may frequently exploit similar features of visual perception. This paper outlines how different forms of protective markings can be understood from predator perception and illustrates how this is fundamental in determining the mechanisms underlying, and the interrelation between, different strategies. Suggestions are made for future work, and potential mechanisms discussed in relation to various forms of defensive coloration, including disruptive coloration, eyespots, dazzle markings, motion camouflage, aposematism and mimicry.

scholarly journals Linking the evolution and form of warning coloration in nature

2011 ◽  
Vol 279 (1728) ◽  
pp. 417-426 ◽  
Author(s):  
Martin Stevens ◽  
Graeme D. Ruxton
Keyword(s):  
Mate Choice ◽  
Evolutionary Ecology ◽  
Classical System ◽  
Warning Signal ◽  
Current Understanding ◽  
Warning Coloration ◽  
Warning Signals ◽  
Initial Evolution ◽  
Mechanistic Basis ◽  
Future Work

Many animals are toxic or unpalatable and signal this to predators with warning signals (aposematism). Aposematic appearance has long been a classical system to study predator–prey interactions, communication and signalling, and animal behaviour and learning. The area has received considerable empirical and theoretical investigation. However, most research has centred on understanding the initial evolution of aposematism, despite the fact that these studies often tell us little about the form and diversity of real warning signals in nature. In contrast, less attention has been given to the mechanistic basis of aposematic markings; that is, ‘what makes an effective warning signal?’, and the efficacy of warning signals has been neglected. Furthermore, unlike other areas of adaptive coloration research (such as camouflage and mate choice), studies of warning coloration have often been slow to address predator vision and psychology. Here, we review the current understanding of warning signal form, with an aim to comprehend the diversity of warning signals in nature. We present hypotheses and suggestions for future work regarding our current understanding of several inter-related questions covering the form of warning signals and their relationship with predator vision, learning, and links to broader issues in evolutionary ecology such as mate choice and speciation.

scholarly journals Disruptive coloration, crypsis and edge detection in early visual processing

2006 ◽  
Vol 273 (1598) ◽  
pp. 2141-2147 ◽  
Author(s):  
Martin Stevens ◽  
Innes C Cuthill
Keyword(s):  
Edge Detection ◽  
Pattern Matching ◽  
Visual Processing ◽  
Colour Vision ◽  
The Body ◽  
Detection Algorithms ◽  
Avian Predators ◽  
Early Visual Processing ◽  
Disruptive Coloration ◽  
Risk Of Predation

Many animals use concealing markings to reduce the risk of predation. These include background pattern matching (crypsis), where the coloration matches a random sample of the background and disruptive patterns, whose effectiveness has been hypothesized to lie in breaking up the body into a series of apparently unrelated objects. We have previously established the effectiveness of disruptive coloration against avian predators, using artificial moth-like stimuli with colours designed to match natural backgrounds as perceived by birds. Here, we investigate the mechanism by which disruptive patterns reduce detectability, using a computational vision model of edge detection applied to photographs of our experimental stimuli, calibrated for bird colour vision. We show that, disruptive coloration is effective by exploiting edge detection algorithms that we use to model early visual processing. Thus, ‘false’ edges are detected within the body rather than at its periphery, so inhibiting successful detection of the animal's body outline.

scholarly journals Disruptive coloration and habitat use by seahorses

2019 ◽  
Vol 17 (4) ◽  
Author(s):  
Michele Duarte ◽  
Felipe M. Gawryszewski ◽  
Suzana Ramineli ◽  
Eduardo Bessa
Keyword(s):  
Habitat Use ◽  
Selection Pressure ◽  
Probability Of Detection ◽  
Primary Factor ◽  
Color Morph ◽  
Background Color ◽  
Color Patterns ◽  
Predation Avoidance ◽  
Disruptive Coloration ◽  
Risk Of Predation

ABSTRACT Predation avoidance is a primary factor influencing survival. Therefore, any trait that affects the risk of predation, such as camouflage, is expected to be under selection pressure. Background matching (homochromy) limits habitat use, especially if the habitat is heterogeneous. Another camouflage mechanism is disruptive coloration, which reduces the probability of detection by masking the prey’s body contours. Here we evaluated if disruptive coloration in the longsnout seahorse, Hippocampus reidi, allows habitat use diversification. We analyzed 82 photographs of animals, comparing animal and background color, and registering anchorage substrate (holdfast). We tested whether the presence (disruptive coloration) or absence of bands (plain coloration) predicted occupation of backgrounds of different colors. We also calculated the connectance between seahorse morph and background color or holdfast, as well as whether color morph differed in their preferences for holdfast. Animals with disruptive coloration were more likely to be found in environments with colors different from their own. Furthermore, animals with disruptive coloration occupied more diversified habitats, but as many holdfasts as plain colored animals. Therefore, animals with disruptive coloration were less selective in habitat use than those lacking disruptive color patterns, which agrees with the disruptive coloration hypothesis.

scholarly journals Defining disruptive coloration and distinguishing its functions

2008 ◽  
Vol 364 (1516) ◽  
pp. 481-488 ◽  
Author(s):  
Martin Stevens ◽  
Sami Merilaita
Keyword(s):  
Formal Definition ◽  
Slowing Down ◽  
Disruptive Coloration ◽  
Definition Of ◽  
Future Work

Disruptive coloration breaks up the shape and destroys the outline of an object, hindering detection. The principle was first suggested approximately a century ago, but, although research has significantly increased, the field remains conceptually unstructured and no unambiguous definition exists. This has resulted in variable use of the term, making it difficult to formulate testable hypotheses that are comparable between studies, slowing down advancement in this field. Related to this, a range of studies do not effectively distinguish between disruption and other forms of camouflage. Here, we give a formal definition of disruptive coloration, reorganize a range of sub-principles involved in camouflage and argue that five in particular are specifically related to disruption: differential blending; maximum disruptive contrast; disruption of surface through false edges; disruptive marginal patterns; and coincident disruptive coloration. We discuss how disruptive coloration can be optimized, how it can relate to other forms of camouflage markings and where future work is particularly needed.

scholarly journals Disruptive coloration in cuttlefish: a visual perception mechanism that regulates ontogenetic adjustment of skin patterning

2007 ◽  
Vol 210 (7) ◽  
pp. 1139-1147 ◽  
Author(s):  
A. Barbosa ◽  
L. M. Mathger ◽  
C. Chubb ◽  
C. Florio ◽  
C.-C. Chiao ◽  
...  
Keyword(s):  
Visual Perception ◽  
Disruptive Coloration

scholarly journals Adversarial Attacks on Multi-task Visual Perception for Autonomous Driving

2021 ◽  
Author(s):  
Ibrahim Sobh ◽  
Ahmed Hamed ◽  
Varun Ravi Kumar ◽  
Senthil Yogamani
Keyword(s):  
Neural Networks ◽  
Visual Perception ◽  
Motion Detection ◽  
Deep Neural Networks ◽  
Distance Estimation ◽  
Semantic Segmentation ◽  
Autonomous Driving ◽  
Black Box ◽  
Safety Critical ◽  
Future Work

In recent years, deep neural networks (DNNs) have accomplished impressive success in various applications, including autonomous driving perception tasks. However, current deep neural networks are easily deceived by adversarial attacks. This vulnerability raises significant concerns, particularly in safety-critical applications. As a result, research into attacking and defending DNNs has gained much coverage. In this work, detailed adversarial attacks are applied on a diverse multi-task visual perception deep network across distance estimation, semantic segmentation, motion detection, and object detection. The experiments consider both white and black box attacks for targeted and un-targeted cases, while attacking a task and inspecting the effect on all others, in addition to inspecting the effect of applying a simple defense method. We conclude this paper by comparing and discussing the experimental results, proposing insights and future work. The visualizations of the attacks are available at https://youtu.be/6AixN90budY.

Cuttlefish camouflage: visual perception of size, contrast and number of white squares on artificial checkerboard substrata initiates disruptive coloration

2001 ◽  
Vol 204 (12) ◽  
pp. 2119-2125 ◽  
Author(s):  
Chuan-Chin Chiao ◽  
Roger T. Hanlon
Keyword(s):  
Visual Perception ◽  
Narrow Range ◽  
Body Form ◽  
Black Background ◽  
Sepia Pharaonis ◽  
Disruptive Coloration ◽  
Visual Background ◽  
On Line ◽  
Size Contrast

SUMMARY We investigated some visual background features that influence young cuttlefish, Sepia pharaonis, to change their skin patterning from ‘general resemblance’ of the substratum to disruptive coloration that breaks up their body form. Using computer-generated black/white checkerboard patterns as substrata, we first found that the size of the white squares had to be within a certain narrow range (relative to the size of the cuttlefish ‘white square’) for the animal to exhibit disruptive skin patterning. Second, given the appropriate size of checker, cuttlefish regulated their disruptive skin patterns according to the contrast between white and black squares. Third, by manipulating the number of white squares on a black background, we found that as few as four white squares among 316 black squares (or 1.25%) produced disruptive patterning, yet increasing the number of white squares to 20, 40 or 80 did not increase the frequency of appearance of the cuttlefish ‘white square’, but only its clarity of expression. These results demonstrate that the size, contrast and number of white objects in the surrounding substratum influence the production and expression of disruptive skin patterns in young cuttlefish. Movies available on-line

scholarly journals Cognition does not affect perception: Evaluating the evidence for “top-down” effects

2015 ◽  
Vol 39 ◽  
Author(s):  
Chaz Firestone ◽  
Brian J. Scholl
Keyword(s):  
Visual Perception ◽  
Visual Processing ◽  
Tidal Wave ◽  
Compelling Evidence ◽  
Top Down ◽  
Cognitive Penetrability ◽  
The Past ◽  
Linguistic Representations ◽  
The Mind ◽  
Future Work

AbstractWhat determines what we see? In contrast to the traditional “modular” understanding of perception, according to which visual processing is encapsulated from higher-level cognition, a tidal wave of recent research alleges that states such as beliefs, desires, emotions, motivations, intentions, and linguistic representations exert direct, top-down influences on what we see. There is a growing consensus that such effects are ubiquitous, and that the distinction between perception and cognition may itself be unsustainable. We argue otherwise: None of these hundreds of studies – either individually or collectively – provides compelling evidence for true top-down effects on perception, or “cognitive penetrability.” In particular, and despite their variety, we suggest that these studies all fall prey to only a handful of pitfalls. And whereas abstract theoretical challenges have failed to resolve this debate in the past, our presentation of these pitfalls is empirically anchored: In each case, we show not only how certain studies could be susceptible to the pitfall (in principle), but also how several alleged top-down effects actually are explained by the pitfall (in practice). Moreover, these pitfalls are perfectly general, with each applying to dozens of other top-down effects. We conclude by extracting the lessons provided by these pitfalls into a checklist that future work could use to convincingly demonstrate top-down effects on visual perception. The discovery of substantive top-down effects of cognition on perception would revolutionize our understanding of how the mind is organized; but without addressing these pitfalls, no such empirical report will license such exciting conclusions.

Behavioral decisions made under the risk of predation: a review and prospectus

1990 ◽  
Vol 68 (4) ◽  
pp. 619-640 ◽  
Author(s):  
Steven L. Lima ◽  
Lawrence M. Dill
Keyword(s):  
Decision Making ◽  
Predation Risk ◽  
Animal Behavior ◽  
Behavioral Characteristics ◽  
Evolutionary Time ◽  
Animal Reproduction ◽  
Trade Offs ◽  
Risk Of Predation ◽  
Future Work ◽  
Insight Into

Predation has long been implicated as a major selective force in the evolution of several morphological and behavioral characteristics of animals. The importance of predation during evolutionary time is clear, but growing evidence suggests that animals also have the ability to assess and behaviorally influence their risk of being preyed upon in ecological time (i.e., during their lifetime). We develop an abstraction of the predation process in which several components of predation risk are identified. A review of the literature indicates that an animal's ability to assess and behaviorally control one or more of these components strongly influences decision making in feeding animals, as well as in animals deciding when and how to escape predators, when and how to be social, or even, for fishes, when and how to breathe air. This review also reveals that such decision making reflects apparent trade-offs between the risk of predation and the benefits to be gained from engaging in a given activity. Despite this body of evidence, several areas in the study of animal behavior have received little or no attention from a predation perspective. We identify several such areas, the most important of which is that dealing with animal reproduction. Much work also remains regarding the precise nature of the risk of predation and how it is actually perceived by animals, and the extent to which they can behaviorally control their risk of predation. Mathematical models will likely play a major role in future work, and we suggest that modelers strive to consider the potential complexity in behavioral responses to predation risk. Overall, since virtually every animal is potential prey for others, research that seriously considers the influence of predation risk will provide significant insight into the nature of animal behavior.

scholarly journals Diseño y construcción de un colorímetro para identificar el desgaste de fusibles comerciales usando sensores fotoeléctricos

2020 ◽  
pp. 16-23
Author(s):  
M. Azucena Torres-Flores ◽  
Irma Martínez-Carrillo ◽  
Carlos Juárez-Toledo
Keyword(s):  
Energy Consumption ◽  
Visual Perception ◽  
Electronic Circuit ◽  
Light Reflection ◽  
3D Printer ◽  
Electrical System ◽  
Light Emitting ◽  
Poor Condition ◽  
Future Work

Color is a property that we are able to observe thanks to our visual perception; however, an instrument is necessary to perform the quantification on the RGB scale. The purpose of this work is to design and build a colorimeter to identify the wear degree of a conventional residential fuse, the fuse has been exposed to normal wear. The study is carried out using the quantification of light reflection on the RGB scale. The developed sensor consists of: - A cylindrical base made on a 3D printer, which allows the external light to be isolated and the upper part of the fuse socket inserted. - An electronic circuit made up of RGB light emitting led and a photoresistor. - An Arduino program that measures the reflection of the fuse on the RGB scale. Implementing the sensor will allow the identification of fuses in poor condition, which can cause failures in the electrical system. Future work will be aimed at quantifying the increase of energy consumption due to the use of fuses in poor condition transferred in RGB space.

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