Department of Geography, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP Wales UK.
Computer Science, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP Wales UK.
Mov Ecol. 2015 Sep 16;3(1):24. doi: 10.1186/s40462-015-0051-8. eCollection 2015.
Whether, and how, animals move requires them to assess their environment to determine the most appropriate action and trajectory, although the precise way the environment is scanned has been little studied. We hypothesized that head attitude, which effectively frames the environment for the eyes, and the way it changes over time, would be modulated by the environment.
To test this, we used a head-mounted device (Human-Interfaced Personal Observation platform - HIPOP) on people moving through three different environments; a botanical garden ('green' space), a reef ('blue' space), and a featureless corridor, to examine if head movement in the vertical axis differed between environments. Template matching was used to identify and quantify distinct behaviours.
The data on head pitch from all subjects and environments over time showed essentially continuous clear waveforms with varying amplitude and wavelength. There were three stylised behaviours consisting of smooth, regular peaks and troughs in head pitch angle and variable length fixations during which the head pitch remained constant. These three behaviours accounted for ca. 40 % of the total time, with irregular head pitch changes accounting for the rest. There were differences in rates of manifestation of behaviour according to environment as well as environmentally different head pitch values of peaks, troughs and fixations. Finally, although there was considerable variation in head pitch angles, the peak and trough values bounded most of the variation in the fixation pitch values. It is suggested that the constant waveforms in head pitch serve to inform people about their environment, providing a scanning mechanism. Particular emphasis to certain sectors is manifest within the peak and trough limits and these appear modulated by the distribution of the points where fixation, interpreted as being due to objects of interest, occurs. This behaviour explains how animals allocate processing resources to the environment and shows promise for movement studies attempting to elucidate which parts of the environment affect movement trajectories.
动物是否以及如何移动，需要它们评估环境以确定最合适的行动和轨迹，尽管环境扫描的精确方式还很少研究。我们假设头部姿势（有效地为眼睛构建环境）及其随时间的变化方式会受到环境的调节。
为了验证这一点，我们在人们穿过三个不同环境（植物园“绿色”空间、珊瑚礁“蓝色”空间和无特征走廊）时使用了头戴式设备（人-机接口个人观测平台-HIPOP），以检查头部在垂直轴上的运动是否在环境之间有所不同。模板匹配用于识别和量化不同的行为。
所有受试者和环境的头部俯仰角随时间变化的数据显示出本质上是连续的清晰波形，具有不同的幅度和波长。有三种定型行为，包括头部俯仰角的平滑、规则的峰谷和可变长度的注视，在此期间头部俯仰角保持不变。这三种行为约占总时间的 40%，其余部分为不规则的头部俯仰变化。根据环境以及头部俯仰角的峰值、低谷和注视的环境不同值，行为的表现率存在差异。最后，尽管头部俯仰角有很大的变化，但峰值和低谷值限制了大部分固定俯仰值的变化。因此，头部俯仰的恒定波形有助于人们了解环境，提供一种扫描机制。在峰值和低谷限制内表现出对特定区域的特别关注，并且这些区域似乎受到注视点分布的调节，这些注视点解释为对感兴趣的物体的关注。这种行为解释了动物如何分配处理资源到环境中，并为试图阐明哪些环境部分影响运动轨迹的运动研究提供了希望。
