Cuttlefish use visual cues to control three-dimensional skin papillae for camouflage

2009 ◽  
Vol 195 (6) ◽  
pp. 547-555 ◽  
Author(s):  
Justine J. Allen ◽  
Lydia M. Mäthger ◽  
Alexandra Barbosa ◽  
Roger T. Hanlon
Keyword(s):  
Visual Cues ◽  
Three Dimensional

scholarly journals Can't tell the caterpillars from the trees: countershading enhances survival in a woodland

2008 ◽  
Vol 275 (1651) ◽  
pp. 2539-2545 ◽  
Author(s):  
Hannah M Rowland ◽  
Innes C Cuthill ◽  
Ian F Harvey ◽  
Michael P Speed ◽  
Graeme D Ruxton
Keyword(s):  
Visual Cues ◽  
Field Experiments ◽  
Three Dimensional ◽  
Shape From Shading ◽  
The Body ◽  
Colour Pattern ◽  
Free Living ◽  
Background Matching ◽  
Lepidopteran Larvae ◽  
Beech Tree

Perception of the body's outline and three-dimensional shape arises from visual cues such as shading, contour, perspective and texture. When a uniformly coloured prey animal is illuminated from above by sunlight, a shadow may be cast on the body, generating a brightness contrast between the dorsal and ventral surfaces. For animals such as caterpillars, which live among flat leaves, a difference in reflectance over the body surface may degrade the degree of background matching and provide cues to shape from shading. This may make otherwise cryptic prey more conspicuous to visually hunting predators. Cryptically coloured prey are expected to match their substrate in colour, pattern and texture (though disruptive patterning is an exception), but they may also abolish self-shadowing and therefore either reduce shape cues or maintain their degree of background matching through countershading: a gradation of pigment on the body of an animal so that the surface closest to illumination is darker. In this study, we report the results from a series of field experiments where artificial prey resembling lepidopteran larvae were presented on the upper surfaces of beech tree branches so that they could be viewed by free-living birds. We demonstrate that countershading is superior to uniform coloration in terms of reducing attack by free-living predators. This result persisted even when we fixed prey to the underside of branches, simulating the resting position of many tree-living caterpillars. Our experiments provide the first demonstration, in an ecologically valid visual context, that shadowing on bodies (such as lepidopteran larvae) provides cues that visually hunting predators use to detect potential prey species, and that countershading counterbalances shadowing to enhance cryptic protection.

scholarly journals What you see is where you go: visibility influences movement decisions of a forest bird navigating a three-dimensional-structured matrix

2021 ◽  
Vol 17 (1) ◽  
pp. 20200478
Author(s):  
Job Aben ◽  
Johannes Signer ◽  
Janne Heiskanen ◽  
Petri Pellikka ◽  
Justin M. J. Travis
Keyword(s):  
Physical Environment ◽  
Visual Cues ◽  
Three Dimensional ◽  
Forest Birds ◽  
Lidar Data ◽  
Perceptual Range ◽  
Movement Data ◽  
Structured Matrix ◽  
Viewshed Analysis ◽  
Step Selection

Animal spatial behaviour is often presumed to reflect responses to visual cues. However, inference of behaviour in relation to the environment is challenged by the lack of objective methods to identify the information that effectively is available to an animal from a given location. In general, animals are assumed to have unconstrained information on the environment within a detection circle of a certain radius (the perceptual range; PR). However, visual cues are only available up to the first physical obstruction within an animal's PR, making information availability a function of an animal's location within the physical environment (the effective visual perceptual range; EVPR). By using LiDAR data and viewshed analysis, we modelled forest birds' EVPRs at each step along a movement path. We found that the EVPR was on average 0.063% that of an unconstrained PR and, by applying a step-selection analysis, that individuals are 1.55 times more likely to move to a tree within their EVPR than to an equivalent tree outside it. This demonstrates that behavioural choices can be substantially impacted by the characteristics of an individual's EVPR and highlights that inferences made from movement data may be improved by accounting for the EVPR.

scholarly journals Lure, retain, and catch malaria mosquitoes. How heat and humidity improve odour-baited trap performance

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Antoine Cribellier ◽  
Jeroen Spitzen ◽  
Henry Fairbairn ◽  
Cedric van de Geer ◽  
Johan L. van Leeuwen ◽  
...  
Keyword(s):  
Short Range ◽  
Visual Cues ◽  
Three Dimensional ◽  
Field Testing ◽  
Counter Flow ◽  
Flight Behaviour ◽  
Baited Traps ◽  
Close Range ◽  
Malaria Mosquitoes ◽  
Host Cues

Abstract Background When seeking a human for a blood meal, mosquitoes use several cues to detect and find their hosts. From this knowledge, counter-flow odour-baited traps have been developed that use a combination of CO2, human-mimicking odour, visual cues and circulating airflow to attract and capture mosquitoes. Initially developed for monitoring, these traps are now also being considered as promising vector control tools. The traps are attractive to host-seeking mosquitoes, but their capture efficiency is low. It has been hypothesized that the lack of short-range host cues, such as heat and increased local humidity, often prevent mosquitoes from getting close enough to get caught; this lack might even trigger avoidance manoeuvres near the capture region. Methods This study investigated how close-range host cues affect the flight behaviour of Anopheles female malaria mosquitoes around odour-baited traps, and how this affects trap capture performance. For this, a novel counter-flow odour-baited trap was developed, the M-Tego. In addition to the usual CO2 and odour-blend, this trap can provide the short-range host cues, heat and humidity. Systematically adding or removing these two cues tested how this affected the trap capture percentages and flight behaviour. First, capture percentages of the M-Tego with and without short-range host cues to the BG-Suna trap were compared, in both laboratory and semi-field testing. Then, machine-vision techniques were used to track the three-dimensional flight movements of mosquitoes around the M-Tego. Results With heat and humidity present, the M-Tego captured significantly more mosquitoes as capture percentages almost doubled. Comparing the flight behaviour around the M-Tego with variable close-range host cues showed that when these cues were present, flying mosquitoes were more attracted to the trap and spent more time there. In addition, the M-Tego was found to have a better capture mechanism than the BG-Suna, most likely because it does not elicit previously observed upward avoiding manoeuvres. Conclusions Results suggest that adding heat and humidity to an odour-baited trap lures more mosquitoes close to the trap and retains them there longer, resulting in higher capture performance. These findings support the development of control tools for fighting mosquito-borne diseases such as malaria.

Responsiveness of Clare-Bishop neurons to visual cues associated with motion of a visual stimulus in three-dimensional space

1985 ◽  
Vol 25 (3) ◽  
pp. 407-414 ◽  
Author(s):  
Keisuke Toyama ◽  
Yukio Komatsu ◽  
Haruo Kasai ◽  
Kei Fujii ◽  
Kazukiyo Umetani
Keyword(s):  
Visual Stimulus ◽  
Visual Cues ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Three Dimensional Space

scholarly journals 3D Object Detection and Recognition for Robotic Grasping Based on RGB-D Images and Global Features

2017 ◽  
Vol 42 (3) ◽  
pp. 219-237 ◽  
Author(s):  
Witold Czajewski ◽  
Krzysztof Kołomyjec
Keyword(s):  
Point Cloud ◽  
Visual Cues ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Microsoft Kinect ◽  
Global Features ◽  
Visual Appearance ◽  
Validation Set ◽  
3D Object Detection ◽  
Detection And Recognition

AbstractThis paper describes the results of experiments on detection and recognition of 3D objects in RGB-D images provided by the Microsoft Kinect sensor. While the studies focus on single image use, sequences of frames are also considered and evaluated. Observed objects are categorized based on both geometrical and visual cues, but the emphasis is laid on the performance of the point cloud matching method. To this end, a rarely used approach consisting of independent VFH and CRH descriptors matching, followed by ICP and HV algorithms from the Point Cloud Library is applied. Successfully recognized objects are then subjected to a classical 2D analysis based on color histogram comparison exclusively with objects in the same geometrical category. The proposed two-stage approach allows to distinguish objects of similar geometry and different visual appearance, like soda cans of various brands. By separating geometry and color identification phases, the applied system is still able to categorize objects based on their geometry, even if there is no color match. The recognized objects are then localized in the three-dimensional space and autonomously grasped by a manipulator. To evaluate this approach, a special validation set was created, and additionally a selected scene from the Washington RGB-D Object Dataset was used.

scholarly journals Comparing the Visual Representations and Performance of Humans and Deep Neural Networks

2018 ◽  
Vol 28 (1) ◽  
pp. 34-39 ◽  
Author(s):  
Robert A. Jacobs ◽  
Christopher J. Bates
Keyword(s):  
Neural Networks ◽  
Visual Cues ◽  
Deep Neural Networks ◽  
Three Dimensional ◽  
Visual Representations ◽  
Dimensional Structure ◽  
Processing Strategies ◽  
Psychological Models ◽  
Statistical Regularities ◽  
And Performance

Although deep neural networks (DNNs) are state-of-the-art artificial intelligence systems, it is unclear what insights, if any, they provide about human intelligence. We address this issue in the domain of visual perception. After briefly describing DNNs, we provide an overview of recent results comparing human visual representations and performance with those of DNNs. In many cases, DNNs acquire visual representations and processing strategies that are very different from those used by people. We conjecture that there are at least two factors preventing them from serving as better psychological models. First, DNNs are currently trained with impoverished data, such as data lacking important visual cues to three-dimensional structure, data lacking multisensory statistical regularities, and data in which stimuli are unconnected to an observer’s actions and goals. Second, DNNs typically lack adaptations to capacity limits, such as attentional mechanisms, visual working memory, and compressed mental representations biased toward preserving task-relevant abstractions.

scholarly journals Appraising the intention of other people: Ecological validity and procedures for investigating effects of lighting for pedestrians

2017 ◽  
Vol 51 (1) ◽  
pp. 111-130 ◽  
Author(s):  
S Fotios ◽  
M Johansson
Keyword(s):  
Power Distribution ◽  
Visual Cues ◽  
Spectral Power ◽  
Ecological Validity ◽  
Three Dimensional ◽  
Public Spaces ◽  
Light Level ◽  
Urban Environments ◽  
Spectral Power Distribution ◽  
Outdoor Environments

One of the aims of outdoor lighting in public spaces, such as pathways and subsidiary roads, is to help pedestrians to evaluate the intentions of other people. This paper discusses how a pedestrians' appraisal of another persons' intentions in artificially lit outdoor environments can be studied. We review the visual cues that might be used, and the experimental design with which effects of changes in lighting could be investigated to best resemble the pedestrian experience in artificially lit urban environments. Proposals are made to establish appropriate operationalisation of the identified visual cues, choice of methods and measurements representing critical situations. It is concluded that the intentions of other people should be evaluated using facial emotion recognition; eye-tracking data suggest a tendency to make these observations at an interpersonal distance of 15 m and for a duration of 500 ms. Photographs are considered suitable for evaluating the effect of changes in light level and spectral power distribution. To support investigation of changes in spatial distribution, further investigation is needed with three-dimensional targets. Further data are also required to examine the influence of glare.

V4 lesions in macaques affect both single- and multiple-viewpoint shape discriminations

1998 ◽  
Vol 15 (2) ◽  
pp. 359-367 ◽  
Author(s):  
WILLIAM H. MERIGAN ◽  
HONG AN PHAM
Keyword(s):  
Visual Field ◽  
Visual Cues ◽  
Three Dimensional ◽  
Right Visual Field ◽  
Shape Discrimination ◽  
Area V4 ◽  
3D Objects ◽  
Contrast Thresholds ◽  
Object Similarity ◽  
Visual Shape

The role of cortical area V4 in complex shape discriminations was studied by testing the effects of V4 lesions in macaques on the ability to visually discriminate between images of three-dimensional (3D) objects from different viewpoints. Stimuli were presented in pairs in the lower left or lower right visual field quadrants about 4 deg from the fovea, and the monkeys judged on each trial whether the two views were of the same or of different objects. Object similarity was varied to determine a threshold shape difference. V4 lesions caused profound, retinotopic, and apparently permanent disruptions of discrimination, regardless of whether the images represented single or multiple viewpoints. In V4 lesioned portions of the visual field, monkeys could discriminate objects only when they differed much more grossly in shape than was true in control locations. These effects of the lesion were virtually identical for discriminations that had been learned before lesions were placed and for those learned afterwards. As in previous studies, V4 lesions elevated contrast thresholds by approximately a factor of two, but control observations showed that this was not the basis of the disruption of shape discrimination. Manipulation of cues to shape showed that in control locations, monkeys maintained excellent shape discrimination despite a variety of stimulus alterations, whereas in V4 lesioned areas their performance was easily disrupted. This finding suggests that V4 may support visual shape discriminations by facilitating the use of multiple visual cues. However, the fact that single-viewpoint and multiple-viewpoint discriminations were similarly affected indicates that the disruption was not specific to 3D shape discrimination, but may apply to a variety of subtle discriminations.

scholarly journals Flight behaviour of malaria mosquitoes around odour-baited traps: capture and escape dynamics

2018 ◽  
Vol 5 (8) ◽  
pp. 180246 ◽  
Author(s):  
Antoine Cribellier ◽  
Jens A. van Erp ◽  
Alexandra Hiscox ◽  
Martin J. Lankheet ◽  
Johan L. van Leeuwen ◽  
...  
Keyword(s):  
Visual Cues ◽  
Control Strategies ◽  
Three Dimensional ◽  
Anopheles Coluzzii ◽  
Flight Behaviour ◽  
Flight Direction ◽  
Host Seeking ◽  
Baited Traps ◽  
Global Vector ◽  
Malaria Mosquitoes

Host-seeking mosquitoes rely on a range of sensory cues to find and approach blood hosts, as well as to avoid host detection. By using odour blends and visual cues that attract anthropophilic mosquitoes, odour-baited traps have been developed to monitor and control human pathogen-transmitting vectors. Although long-range attraction of such traps has already been studied thoroughly, close-range response of mosquitoes to these traps has been largely ignored. Here, we studied the flight behaviour of female malaria mosquitoes ( Anopheles coluzzii ) in the immediate vicinity of a commercially available odour-baited trap, positioned in a hanging and standing orientation. By analysing more than 2500 three-dimensional flight tracks, we elucidated how mosquitoes reacted to the trap, and how this led to capture. The measured flight dynamics revealed two distinct stereotypical behaviours: (i) mosquitoes that approached a trap tended to simultaneously fly downward towards the ground; (ii) mosquitoes that came close to a trap changed their flight direction by rapidly accelerating upward. The combination of these behaviours led to strikingly different flight patterns and capture dynamics, resulting in contrasting short-range attractiveness and capture mechanism of the oppositely oriented traps. These new insights may help in improving odour-baited traps, and consequently their contribution in global vector control strategies.

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