Shape from shading in pigeons

Cook, Robert G.; Qadri, Muhammad A. J.; Kieres, Art; Commons-Miller, Nicholas

doi:10.1016/j.cognition.2012.05.007

Cited by 34 publications

(48 citation statements)

References 39 publications

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“…This early mediation of the discrimination likely reflects the processing of immediately available static pose information during both the static and dynamic conditions. Rapid discrimination of static cues has been seen previously in a shading-based discrimination with pigeons in a similar go/no-go procedure [28]. After a few seconds, a second period emerges where peck rates to the dynamic and static negative conditions further diverge in value.…”

Section: Discussionsupporting

confidence: 61%

Discrimination of Complex Human Behavior by Pigeons (Columba livia) and Humans

2014

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The cognitive and neural mechanisms for recognizing and categorizing behavior are not well understood in non-human animals. In the current experiments, pigeons and humans learned to categorize two non-repeating, complex human behaviors (“martial arts” vs. “Indian dance”). Using multiple video exemplars of a digital human model, pigeons discriminated these behaviors in a go/no-go task and humans in a choice task. Experiment 1 found that pigeons already experienced with discriminating the locomotive actions of digital animals acquired the discrimination more rapidly when action information was available than when only pose information was available. Experiments 2 and 3 found this same dynamic superiority effect with naïve pigeons and human participants. Both species used the same combination of immediately available static pose information and more slowly perceived dynamic action cues to discriminate the behavioral categories. Theories based on generalized visual mechanisms, as opposed to embodied, species-specific action networks, offer a parsimonious account of how these different animals recognize behavior across and within species.

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Section: Discussionsupporting

confidence: 61%

Discrimination of Complex Human Behavior by Pigeons (Columba livia) and Humans

2014

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“…That was true of the pigeons (Cook et al, 2012), who showed above-chance discrimination within just a few sessions. Further, if the starlings are able to reliably access surface shading to perceive shape, their learning and performance should not be strongly influenced by irrelevant variations in camera perspective, image color, or lighting direction.…”

Section: Methodsmentioning

confidence: 86%

Shape from shading in starlings (Sturnus vulgaris).

Qadri

Romero

Cook

2014

Journal of Comparative Psychology

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Birds behave as if they quickly and accurately perceive an object-filled visual world. Beyond the extensive research with pigeons, however, there is a large and important gap in our knowledge about the mechanisms of object perception and recognition in other avian visual systems. The pattern of shading reflected from object surfaces is one important optical feature providing fundamental information about shape. To better understand how surface and object shading is processed by a passerine species, five starlings were tested with differentially illuminated convex and concave curved surfaces in three experiments using a simultaneous visual discrimination procedure. Starlings rapidly learned this shape-from-shading discrimination independent of varied lighting direction, surface color, and camera perspective. Variations in the pattern of lighting through experimental manipulations of camera perspective, surface height, contrast, material specularity, and surface shape were consistent with the hypothesis that the starlings perceived these illuminated surfaces as having three-dimensional shape, similar to results previously collected with pigeons. These similarities across different orders of birds indicate that the relative shading for objects in a visual scene is a highly salient feature for shape processing in birds and is likely a highly conserved visual process that is widely distributed within this class of animal.

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“…We tested whether there was an interaction between this orientation response and the background or illumination conditions. Generalized linear mixed models found no significant effect of stimulus or illumination condition per se on orientation (F ¼ 0.882 (4, 129), p ¼ 0.477 and F ¼ 2.044 (2, 129), p ¼ 0.134, respectively), but they did reveal a significant interaction between stimulus and illumination (F ¼ 2.768 (8,129), p ¼ 0.007). Specifically, pairwise contrasts show significantly reduced orientation to illumination in the case of gradient A when illumination was incongruent with the stimulus compared with when the illumination was congruent (adjusted p ¼ 0.008) or bidirectional (adjusted p ¼ 0.040).…”

Section: (B) White Square Asymmetrymentioning

confidence: 96%

“…Cook et al [8] found that pigeons can distinguish convex and concave surfaces defined by shading, but for a human viewer the threedimensional relief seen in the two-dimensional stimuli used does not depend solely on shading, and it is not clear how the birds made this discrimination. To the best of our knowledge, no study has investigated how a non-human animal takes account of the direction of illumination.…”

Section: Introductionmentioning

confidence: 99%

Cuttlefish see shape from shading, fine-tuning coloration in response to pictorial depth cues and directional illumination

2016

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Humans use shading as a cue to three-dimensional form by combining lowlevel information about light intensity with high-level knowledge about objects and the environment. Here, we examine how cuttlefish Sepia officinalis respond to light and shadow to shade the white square (WS) feature in their body pattern. Cuttlefish display the WS in the presence of pebble-like objects, and they can shade it to render the appearance of surface curvature to a human observer, which might benefit camouflage. Here we test how they colour the WS on visual backgrounds containing two-dimensional circular stimuli, some of which were shaded to suggest surface curvature, whereas others were uniformly coloured or divided into dark and light semicircles. WS shading, measured by lateral asymmetry, was greatest when the animal rested on a background of shaded circles and three-dimensional hemispheres, and less on plain white circles or black/white semicircles. In addition, shading was enhanced when light fell from the lighter side of the shaded stimulus, as expected for real convex surfaces. Thus, the cuttlefish acts as if it perceives surface curvature from shading, and takes account of the direction of illumination. However, the direction of WS shading is insensitive to the directions of background shading and illumination; instead the cuttlefish tend to turn to face the light source.

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Shape from shading in pigeons

Cited by 34 publications

References 39 publications

Discrimination of Complex Human Behavior by Pigeons (Columba livia) and Humans

Discrimination of Complex Human Behavior by Pigeons (Columba livia) and Humans

Shape from shading in starlings (Sturnus vulgaris).

Cuttlefish see shape from shading, fine-tuning coloration in response to pictorial depth cues and directional illumination

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