Testing thayer's countershading hypothesis: An image processing approach

@article{Kiltie1989TestingTC,
  title={Testing thayer's countershading hypothesis: An image processing approach},
  author={Richard A. Kiltie},
  journal={Animal Behaviour},
  year={1989},
  volume={38},
  pages={542-544}
}
  • R. Kiltie
  • Published 1 September 1989
  • Biology
  • Animal Behaviour
A. H. Thayer (1896) argued that 'countershaded' animals (with dorsal surfaces more darkly pigmented than ventral surfaces) have ventral shadows visually reduced or completely obliterated when illuminated from above. Concealment of ventral shadows was thought to improve crypsis because it could diminish three-dimensional shape as a cue by which animals might recognize their predators or prey and improve background matching. Although the idea has been widely accepted, it has been little tested… 
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References

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TLDR
This work finds that perception of shape from shading is a global operation which assumes that there is only one light source illuminating the entire visual image, and that if two identical objects are viewed simultaneously and illuminated from different angles, then the authors would be able to perceive three-dimensional shape accurately in only one of them at a time.
Countershading: Universally deceptive or deceptively universal?
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The presence of dark dorsa and light ven tra on animals is often attributed to an adaptive effect of shape-obliteration when illumination is from above, but direct evidence for this effect is scant and alternative explanations for the evolution of the trait are given less attention.
The Law Which Underlies Protective Coloration