Queensland Brain Institute, University of Queensland, St Lucia, QLD 4000, Australia.
Department of Psychology, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK.
Zoology (Jena). 2014 Jun;117(3):163-70. doi: 10.1016/j.zool.2013.10.004. Epub 2013 Dec 4.
The functional significance of the zebra coat stripe pattern is one of the oldest questions in evolutionary biology, having troubled scientists ever since Charles Darwin and Alfred Russel Wallace first disagreed on the subject. While different theories have been put forward to address this question, the idea that the stripes act to confuse or 'dazzle' observers remains one of the most plausible. However, the specific mechanisms by which this may operate have not been investigated in detail. In this paper, we investigate how motion of the zebra's high contrast stripes creates visual effects that may act as a form of motion camouflage. We simulated a biologically motivated motion detection algorithm to analyse motion signals generated by different areas on a zebra's body during displacements of their retinal images. Our simulations demonstrate that the motion signals that these coat patterns generate could be a highly misleading source of information. We suggest that the observer's visual system is flooded with erroneous motion signals that correspond to two well-known visual illusions: (i) the wagon-wheel effect (perceived motion inversion due to spatiotemporal aliasing); and (ii) the barber-pole illusion (misperceived direction of motion due to the aperture effect), and predict that these two illusory effects act together to confuse biting insects approaching from the air, or possibly mammalian predators during the hunt, particularly when two or more zebras are observed moving together as a herd.
斑马条纹图案的功能意义是进化生物学中最古老的问题之一，自从查尔斯·达尔文和阿尔弗雷德·拉塞尔·华莱士首次对此产生分歧以来，一直困扰着科学家们。虽然已经提出了不同的理论来解决这个问题，但条纹起到迷惑或“眩目”观察者的观点仍然是最合理的观点之一。然而，这种观点具体是如何运作的，尚未进行详细研究。在本文中，我们研究了斑马高对比度条纹的运动如何产生可能作为一种运动伪装形式的视觉效果。我们模拟了一种基于生物学的运动检测算法，以分析斑马身体不同部位在视网膜图像移动时产生的运动信号。我们的模拟表明，这些外套图案产生的运动信号可能是一个极具误导性的信息源。我们认为观察者的视觉系统充斥着错误的运动信号，这些信号对应于两种众所周知的视觉错觉：（i）车轮效应（由于时空混叠而感知到的运动反转）；和（ii）理发馆招牌错觉（由于孔径效应而感知到的运动方向错误），并预测这两种错觉效应会共同作用，迷惑从空中飞来的叮咬昆虫，或者在狩猎期间可能迷惑哺乳动物捕食者，特别是当观察到两个或更多斑马一起成群移动时。
