scholarly journals Contrast, contours and the confusion effect in dazzle camouflage

2016 ◽  
Vol 3 (7) ◽  
pp. 160180 ◽  
Author(s):  
Benedict G. Hogan ◽  
Nicholas E. Scott-Samuel ◽  
Innes C. Cuthill
Keyword(s):  
Prey Capture ◽  
Moving Target ◽  
Previous Evidence ◽  
Multiple Functions ◽  
Confusion Effect ◽  
Potential Motion ◽  
Surface Patterns ◽  
Human Participants ◽  
Motion Dazzle ◽  
Camouflage Patterns

‘Motion dazzle camouflage’ is the name for the putative effects of highly conspicuous, often repetitive or complex, patterns on parameters important in prey capture, such as the perception of speed, direction and identity. Research into motion dazzle camouflage is increasing our understanding of the interactions between visual tracking, the confusion effect and defensive coloration. However, there is a paucity of research into the effects of contrast on motion dazzle camouflage: is maximal contrast a prerequisite for effectiveness? If not, this has important implications for our recognition of the phenotype and understanding of the function and mechanisms of potential motion dazzle camouflage patterns. Here we tested human participants' ability to track one moving target among many identical distractors with surface patterns designed to test the influence of these factors. In line with previous evidence, we found that targets with stripes parallel to the object direction of motion were hardest to track. However, reduction in contrast did not significantly influence this result. This finding may bring into question the utility of current definitions of motion dazzle camouflage, and means that some animal patterns, such as aposematic or mimetic stripes, may have previously unrecognized multiple functions.

scholarly journals In the corner of the eye: camouflaging motion in the peripheral visual field

2020 ◽  
Vol 287 (1918) ◽  
pp. 20192537
Author(s):  
Ioan E. Smart ◽  
Innes C. Cuthill ◽  
Nicholas E. Scott-Samuel
Keyword(s):  
Visual Field ◽  
Prey Species ◽  
Peripheral Vision ◽  
Movement Duration ◽  
Target Pattern ◽  
Localization Accuracy ◽  
Surface Patterns ◽  
The Mean ◽  
Mean Luminance ◽  
Human Participants

Most animals need to move, and motion will generally break camouflage. In many instances, most of the visual field of a predator does not fall within a high-resolution area of the retina and so, when an undetected prey moves, that motion will often be in peripheral vision. We investigate how this can be exploited by prey, through different patterns of movement, to reduce the accuracy with which the predator can locate a cryptic prey item when it subsequently orients towards a target. The same logic applies for a prey species trying to localize a predatory threat. Using human participants as surrogate predators, tasked with localizing a target on peripherally viewed computer screens, we quantify the effects of movement (duration and speed) and target pattern. We show that, while motion is certainly detrimental to camouflage, should movement be necessary, some behaviours and surface patterns reduce that cost. Our data indicate that the phenotype that minimizes localization accuracy is unpatterned, having the mean luminance of the background, does not use a startle display prior to movement, and has short (below saccadic latency), fast movements.

scholarly journals The evolution of patterning during movement in a large-scale citizen science game

2021 ◽  
Vol 288 (1942) ◽  
pp. 20202823
Author(s):  
Anna E. Hughes ◽  
David Griffiths ◽  
Jolyon Troscianko ◽  
Laura A. Kelley
Keyword(s):  
Citizen Science ◽  
Optimal Strategy ◽  
Large Scale ◽  
Programming Approach ◽  
Moving Target ◽  
High Contrast ◽  
Low Contrast ◽  
Geometric Patterns ◽  
Motion Energy ◽  
Motion Dazzle

The motion dazzle hypothesis posits that high contrast geometric patterns can cause difficulties in tracking a moving target and has been argued to explain the patterning of animals such as zebras. Research to date has only tested a small number of patterns, offering equivocal support for the hypothesis. Here, we take a genetic programming approach to allow patterns to evolve based on their fitness (time taken to capture) and thus find the optimal strategy for providing protection when moving. Our ‘Dazzle Bug’ citizen science game tested over 1.5 million targets in a touch screen game at a popular visitor attraction. Surprisingly, we found that targets lost pattern elements during evolution and became closely background matching. Modelling results suggested that targets with lower motion energy were harder to catch. Our results indicate that low contrast, featureless targets offer the greatest protection against capture when in motion, challenging the motion dazzle hypothesis.

scholarly journals No evidence for motion dazzle in an evolutionary citizen science game

2019 ◽  
Author(s):  
Anna E. Hughes ◽  
David Griffiths ◽  
Jolyon Troscianko ◽  
Laura A. Kelley
Keyword(s):  
Genetic Programming ◽  
Citizen Science ◽  
Optimal Strategy ◽  
Programming Approach ◽  
Moving Target ◽  
High Contrast ◽  
Low Contrast ◽  
Geometric Patterns ◽  
Motion Energy ◽  
Motion Dazzle

AbstractThe motion dazzle hypothesis posits that high contrast geometric patterns can cause difficulties in tracking a moving target, and has been argued to explain the patterning of animals such as zebras. Research to date has only tested a small number of patterns, offering equivocal support for the hypothesis. Here, we take a genetic programming approach to allow patterns to evolve based on their fitness (time taken to capture) and thus find the optimal strategy for providing protection when moving. Our ‘Dazzle Bug’ citizen science game tested over 1.5 million targets in a touch screen game at a popular visitor attraction. Surprisingly, we found that targets lost pattern elements during evolution and became closely background matching. Modelling results suggested that targets with lower motion energy were harder to catch. Our results indicate that low contrast, featureless targets offer the greatest protection against capture when in motion, challenging the motion dazzle hypothesis.

The Role of Visual Distractors in the Simon Effect

2017 ◽  
Vol 64 (6) ◽  
pp. 387-397 ◽  
Author(s):  
Luisa Lugli ◽  
Stefania D’Ascenzo ◽  
Roberto Nicoletti ◽  
Carlo Umiltà
Keyword(s):  
Simon Effect ◽  
Simon Task ◽  
Automatic Generation ◽  
Spatial Code ◽  
Attentional Model ◽  
Previous Evidence ◽  
Spatial Stimulus ◽  
Attentional Resources ◽  
Code Changes

Abstract. The Simon effect lies on the automatic generation of a stimulus spatial code, which, however, is not relevant for performing the task. Results typically show faster performance when stimulus and response locations correspond, rather than when they do not. Considering reaction time distributions, two types of Simon effect have been individuated, which are thought to depend on different mechanisms: visuomotor activation versus cognitive translation of spatial codes. The present study aimed to investigate whether the presence of a distractor, which affects the allocation of attentional resources and, thus, the time needed to generate the spatial code, changes the nature of the Simon effect. In four experiments, we manipulated the presence and the characteristics of the distractor. Findings extend previous evidence regarding the distinction between visuomotor activation and cognitive translation of spatial stimulus codes in a Simon task. They are discussed with reference to the attentional model of the Simon effect.

Where's That Wascally Wilber? The Challenges of Hitting a Moving Target

PsycCRITIQUES ◽  
2007 ◽  
Vol 52 (13) ◽  
Author(s):  
Douglas A. MacDonald
Keyword(s):  
Moving Target

Pediatric rehabilitation psychology: Rehabilitating a moving target.

2017 ◽  
Vol 62 (3) ◽  
pp. 223-226 ◽  
Author(s):  
Jacqueline N. Kaufman ◽  
Sarah Lahey ◽  
Beth S. Slomine
Keyword(s):  
Moving Target ◽  
Pediatric Rehabilitation ◽  
Rehabilitation Psychology

Dominance determines fish community biomass in a temperate seagrass ecosystem

2019 ◽  
Author(s):  
Aaron Matthius Eger ◽  
Rebecca J. Best ◽  
Julia Kathleen Baum
Keyword(s):  
Species Richness ◽  
Ecosystem Function ◽  
Fish Community ◽  
Prey Capture ◽  
Fish Communities ◽  
Functional Trait ◽  
Ecosystem Functions ◽  
Community Biomass ◽  
Ecosystem Valuation ◽  
Species Abundances

Biodiversity and ecosystem function are often correlated, but there are multiple hypotheses about the mechanisms underlying this relationship. Ecosystem functions such as primary or secondary production may be maximized by species richness, evenness in species abundances, or the presence or dominance of species with certain traits. Here, we combined surveys of natural fish communities (conducted in July and August, 2016) with morphological trait data to examine relationships between diversity and ecosystem function (quantified as fish community biomass) across 14 subtidal eelgrass meadows in the Northeast Pacific (54° N 130° W). We employed both taxonomic and functional trait measures of diversity to investigate if ecosystem function is driven by species diversity (complementarity hypothesis) or by the presence or dominance of species with particular trait values (selection or dominance hypotheses). After controlling for environmental variation, we found that fish community biomass is maximized when taxonomic richness and functional evenness is low, and in communities dominated by species with particular trait values – those associated with benthic habitats and prey capture. While previous work on fish communities has found that species richness is positively correlated with ecosystem function, our results instead highlight the capacity for regionally prevalent and locally dominant species to drive ecosystem function in moderately diverse communities. We discuss these alternate links between community composition and ecosystem function and consider their divergent implications for ecosystem valuation and conservation prioritization.

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