Visual perception and motor control in birls and humans

作为物体距离线索的立体视觉在动物中是一种罕见的发明，因为它需要位于前方的眼睛，它们之间的距离相对较大。一种更常见的获得深度的方法是通过运动视差-作为观察者在空间中运动的结果，物体在视网膜上的图像的位移。尽管运动视差比立体视觉更普遍，但它的研究却较少。 立体视觉和运动视差依赖于比较从不同视点拍摄的视图。了解它们之间的距离是至关重要的。虽然两眼间距离是一个生理常数，但运动视差的后续测量之间的距离-即物体和观察者之间的速度-可能不可用。从理论上讲，不知道观察者的速度可以通过以两种不同的速度移动来克服。如果知道它们之间的差异，就可以计算出距离。 我的研究旨在验证这一假说是否能解释头部摆动行为--也就是说，步行的鸽子和许多其他鸟类头部的特殊摆动运动。使用复杂的虚拟现实设置，我们可以分离并重新定义鸟的运动和这种运动引起的视网膜图像运动之间的关系。除了研究头部运动的视觉控制外，我们还将研究两个内部传感器系统的作用：头部的前庭系统和下脊柱的腰骶椎管系统，我们都希望参与头部摆动行为的控制。比较研究哪些鸟会摇头，哪些鸟不会，将揭示摇头的进化起源。 这一系列的研究可能会揭示摇头的功能意义，这一点长期以来一直困扰着研究人员和普通人。此外，我们的目标是将鸽子发展成为一种研究动物运动控制的通用模型，这种动物比非人类灵长类动物更容易进行研究，并且与我们分享了这样一个事实，即它在两条腿上花费了相当长的时间。

Stereopsis as a cue to the distance of objects is a rare invention among animals as it requires frontally posi- tioned eyes with a relatively large distance between them. A more common way to obtain depth is by means of motion parallax - the displacement of an object's image on the retina as a result of an observer's motion through space. Even though more ubiquitous than stereopsis, motion parallax is less well studied. Stereopsis and motion parallax rely on comparing views taken from different viewpoints. Knowledge about the distance between them is crucial. While interocular distance is a physiological constant, the distance traveled between subsequent measurements for motion parallax - that is, the speed between object and observer - may not be available. Theoretically, not knowing an observer's speed can be overcome by moving with two different speeds. If the difference between them is known, distance can be calculated. My research aims to test whether this hypothesis provides an explanation for head-bobbing behaviour - that is, the peculiar oscillating movement of the head of walking pigeons, and many other birds. Using a complex virtual-reality setup, we can uncouple and then re-define the relation between the movement of the bird and the retinal image motion which this movement induces. In addition to studying visual control of head-movements, we will also investigate the role of two interial sensor systems: the vestibular system in the head, and the lumbosacral vertebral canal system in the lower spine which we both expect to be involved in the control of head-bobbing behaviour. A comparative study into which birds head-bob and which ones do not will reveal evolutionary origin of head-bobbing. This line of research will likely reveal the functional significance of head-bobbing which has puzzled researchers and lay people alike for a long time. Furthermore, we aim to develop the pigeon into a general model for the study of motor control in an animal which is much more accessible to research than non-human primates and that shares with us the fact that it spends a considerable time of its life on two legs.