Troje Nikolaus F, Aust Ulrike
Department of Psychology, Queen's University, 62 Arch Street, Kingston, Ontario K7M 3N6, Canada.
Vision Res. 2013 Mar 7;79:47-55. doi: 10.1016/j.visres.2013.01.002. Epub 2013 Jan 19.
Biological motion point-light displays are a rich and versatile instrument to study perceptual organization. Humans are able to retrieve information from biological motion through at least two different channels: The global articulated structure as revealed by the non-rigid, yet highly constrained deformation of the dot pattern, and the characteristics of local motion trajectories of individual dots. Here, we tested eight pigeons on a task in which they had to discriminate a left-facing from a right-facing biological motion point-light figure. Since the two stimuli were mirror-flipped versions of each other, we were not sure if the birds would be able to solve the task at all. However, all birds learned the discrimination quickly and performed at high accuracy. We then challenged them with a number of test trials introduced into the sequence of the normal training trials. Tested on backwards moving walkers, the majority of the birds indicated that they used local motion cues to solve the training task, while the remaining birds obviously used global, configural cues. Testing the pigeons on different versions of scrambled biological motion confirmed that each individual bird had made a clear decision for one of the two potentially available strategies. While we confirm a previously described local precedence in processing visual patterns, the fact that some birds used global features suggests that even the birds who relied on local cues probably dispose of the perceptual abilities to use global structure, but "chose" to not use them.
生物运动点光显示是研究知觉组织的一种丰富且通用的工具。人类能够通过至少两种不同的通道从生物运动中提取信息：由点图案的非刚性但高度受限的变形所揭示的全局关节结构，以及各个点的局部运动轨迹的特征。在此，我们对八只鸽子进行了一项任务测试，在该任务中它们必须区分向左和向右的生物运动点光图形。由于这两种刺激是彼此的镜像翻转版本，我们不确定鸟类是否根本能够解决该任务。然而，所有鸟类都很快学会了区分并且表现出高精度。然后，我们在正常训练试验序列中引入了一些测试试验来挑战它们。在向后移动的步行者上进行测试时，大多数鸟类表明它们使用局部运动线索来解决训练任务，而其余鸟类显然使用全局、构型线索。在不同版本的打乱生物运动上对鸽子进行测试证实，每只个体鸟类都对两种潜在可用策略之一做出了明确选择。虽然我们证实了先前描述的在处理视觉模式时局部优先的情况，但一些鸟类使用全局特征这一事实表明，即使是依赖局部线索的鸟类可能也具备使用全局结构的知觉能力，只是“选择”不使用它们。
