Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan.
PLoS One. 2013;8(3):e59785. doi: 10.1371/journal.pone.0059785. Epub 2013 Mar 27.
This study offers a new method for examining the bodily, manual, and eye movements of a chimpanzee at the micro-level. A female chimpanzee wore a lightweight head-mounted eye tracker (60 Hz) on her head while engaging in daily interactions with the human experimenter. The eye tracker recorded her eye movements accurately while the chimpanzee freely moved her head, hands, and body. Three video cameras recorded the bodily and manual movements of the chimpanzee from multiple angles. We examined how the chimpanzee viewed the experimenter in this interactive setting and how the eye movements were related to the ongoing interactive contexts and actions. We prepared two experimentally defined contexts in each session: a face-to-face greeting phase upon the appearance of the experimenter in the experimental room, and a subsequent face-to-face task phase that included manual gestures and fruit rewards. Overall, the general viewing pattern of the chimpanzee, measured in terms of duration of individual fixations, length of individual saccades, and total viewing duration of the experimenter's face/body, was very similar to that observed in previous eye-tracking studies that used non-interactive situations, despite the differences in the experimental settings. However, the chimpanzee viewed the experimenter and the scene objects differently depending on the ongoing context and actions. The chimpanzee viewed the experimenter's face and body during the greeting phase, but viewed the experimenter's face and hands as well as the fruit reward during the task phase. These differences can be explained by the differential bodily/manual actions produced by the chimpanzee and the experimenter during each experimental phase (i.e., greeting gestures, task cueing). Additionally, the chimpanzee's viewing pattern varied depending on the identity of the experimenter (i.e., the chimpanzee's prior experience with the experimenter). These methods and results offer new possibilities for examining the natural gaze behavior of chimpanzees.
本研究提供了一种新的方法，可以在微观层面上检查黑猩猩的身体、手部和眼部运动。一只雌性黑猩猩头上戴着一个轻便的头戴式眼动追踪器（60Hz），在与人类实验者进行日常互动时使用。当黑猩猩自由移动头部、手部和身体时，眼动追踪器准确地记录了她的眼部运动。三个摄像机从多个角度记录了黑猩猩的身体和手部运动。我们研究了黑猩猩在这种互动环境中如何观察实验者，以及眼动如何与正在进行的互动背景和动作相关。在每次实验中，我们准备了两种实验定义的情景：实验者出现在实验室内时的面对面问候阶段，以及随后的面对面任务阶段，其中包括手动手势和水果奖励。总的来说，黑猩猩的一般注视模式，以单个注视持续时间、单个扫视长度和实验者面部/身体的总注视持续时间来衡量，与之前使用非互动情境进行的眼动追踪研究非常相似，尽管实验设置有所不同。然而，黑猩猩根据正在进行的背景和动作，以不同的方式观察实验者和场景物体。黑猩猩在问候阶段观察实验者的脸和身体，但在任务阶段也观察实验者的脸和手以及水果奖励。这些差异可以通过黑猩猩和实验者在每个实验阶段（即问候手势、任务提示）产生的不同身体/手部动作来解释。此外，黑猩猩的观察模式还取决于实验者的身份（即，黑猩猩与实验者的先前经验）。这些方法和结果为研究黑猩猩的自然注视行为提供了新的可能性。
