Training and transfer of training in rapid visual search under high target-background similarity

Near-perfect transfer of training was observed in a previous study when participants trained to search for targets on camouflage backgrounds (high target-background similarity) were just as quick to find the camouflaged targets from a different set of images (Boot, Neider & Kramer, 2009). This was achieved in a free viewing paradigm. The unusually robust transfer suggested that participants were learning some general ability to recognize camouflaged targets rather than how each target image stood out against its corresponding background. To explore changes in attentional networks with training in an MRI environment in the future, a paradigm suitable for an fMRI study was tested to determine if the training and transfer benefits remained when using a rapid presentation search paradigm that relies on covert attention. Two groups of participants were tested before and after training, and trained in either camouflage or non-camouflage background conditions. The results showed significant improvements with camouflage training and transfer benefits at the post-training camouflage background test, compared to the control group with non-camouflage training. Both groups were able to use covert attention to detect and recognize camouflaged targets in a brief display, and the camouflage training group transferred this skill to new image set

3D Camouflaging Object using RGB-D Sensors

This paper proposes a new optical camouflage system that uses RGB-D cameras, for acquiring point cloud of background scene, and tracking observers eyes. This system enables a user to conceal an object located behind a display that surrounded by 3D objects. If we considered here the tracked point of observer s eyes is a light source, the system will work on estimating shadow shape of the display device that falls on the objects in background. The system uses the 3d observer s eyes and the locations of display corners to predict their shadow points which have nearest neighbors in the constructed point cloud of background scene.Comment: 6 pages, 12 figures, 2017 IEEE International Conference on SM

Is countershading camouflage robust to lighting change due to weather?

Countershading is a pattern of coloration thought to have evolved in order to implement camouflage. By adopting a pattern of coloration that makes the surface facing towards the sun darker and the surface facing away from the sun lighter, the overall amount of light reflected off an animal can be made more uniformly bright. Countershading could hence contribute to visual camouflage by increasing background matching or reducing cues to shape. However, the usefulness of countershading is constrained by a particular pattern delivering ‘optimal’ camouflage only for very specific lighting conditions. In this study, we test the robustness of countershading camouflage to lighting change due to weather, using human participants as a ‘generic’ predator. In a simulated three-dimensional environment, we constructed an array of simple leaf-shaped items and a single ellipsoidal target ‘prey’. We set these items in two light environments: strongly directional ‘sunny’ and more diffuse ‘cloudy’. The target object was given the optimal pattern of countershading for one of these two environment types or displayed a uniform pattern. By measuring detection time and accuracy, we explored whether and how target detection depended on the match between the pattern of coloration on the target object and scene lighting. Detection times were longest when the countershading was appropriate to the illumination; incorrectly camouflaged targets were detected with a similar pattern of speed and accuracy to uniformly coloured targets. We conclude that structural changes in light environment, such as caused by differences in weather, do change the effectiveness of countershading camouflage

Establishing the behavioural limits for countershaded camouflage

Countershading is a ubiquitous patterning of animals whereby the side that typically faces the highest illumination is darker. When tuned to specific lighting conditions and body orientation with respect to the light field, countershading minimizes the gradient of light the body reflects by counterbalancing shadowing due to illumination, and has therefore classically been thought of as an adaptation for visual camouflage. However, whether and how crypsis degrades when body orientation with respect to the light field is non-optimal has never been studied. We tested the behavioural limits on body orientation for countershading to deliver effective visual camouflage. We asked human participants to detect a countershaded target in a simulated three-dimensional environment. The target was optimally coloured for crypsis in a reference orientation and was displayed at different orientations. Search performance dramatically improved for deviations beyond 15 degrees. Detection time was significantly shorter and accuracy significantly higher than when the target orientation matched the countershading pattern. This work demonstrates the importance of maintaining body orientation appropriate for the displayed camouflage pattern, suggesting a possible selective pressure for animals to orient themselves appropriately to enhance crypsis

Material, Trace, Trauma: Notes on some Recent Acquisitions at the Canadian War Museum and the Legacy of the First World War

Recent acquisitions at the Canadian War Museum are considered in relation to the radical innovations of soldier-artists who endured the somatic conditions of the First World War trenches, privileging materiality and psychic reality over visual perception. Barbara Steinman and Norman Takeuchi bring the past into the present through the indexical presence of black and white photographic fragments and the emotive presentation of lost objects as signifiers of the desires of the absent. Scott Waters and Mary Kavanagh evoke dread and the contingency of death through anamorphic distortion and blinding luminosity. Like the suggestive surfaces of the Museum itself, these works unsettle us to make palpable the psychic toll of war