Lange Joachim, Lappe Markus
Department of Psychology II, University of Muenster, Germany.
Adv Cogn Psychol. 2008 Jul 15;3(4):419-28. doi: 10.2478/v10053-008-0006-3.
Point-light biological motion stimuli provide spatio-temporal information about the structure of the human body in motion. Manipulation of the spatial structure of point-light stimuli reduces the ability of human observers to perceive biological motion. A recent study has reported that interference with the spatial structure of pointlight walkers also reduces the evoked eventrelated potentials over the occipitotemporal cortex, but that interference with the temporal structure of the stimuli evoked event-related potentials similar to normal biological motion stimuli. We systematically investigated the influence of spatial and temporal manipulation on 2 common discrimination tasks and compared it with predictions of a neurocomputational model previously proposed. This model first analyzes the spatial structure of the stimulus independently of the temporal information to derive body posture and subsequently analyzes the temporal sequence of body postures to derive movement direction. Similar to the model predictions, the psychophysical results show that human observers need only intact spatial configuration of the stimulus to discriminate the facing direction of a point-light walker. In contrast, movement direction discrimination needs a fully intact spatiotemporal pattern of the stimulus. The activation levels in the model predict the observed eventrelated potentials for the spatial and temporal manipulations.
点光生物运动刺激提供了关于运动中人体结构的时空信息。对点光刺激的空间结构进行操纵会降低人类观察者感知生物运动的能力。最近一项研究报告称，干扰点光行走者的空间结构也会降低枕颞叶皮质上诱发的事件相关电位，但干扰刺激的时间结构会诱发与正常生物运动刺激相似的事件相关电位。我们系统地研究了空间和时间操纵对两项常见辨别任务的影响，并将其与先前提出的神经计算模型的预测进行了比较。该模型首先独立于时间信息分析刺激的空间结构以得出身体姿势，随后分析身体姿势的时间序列以得出运动方向。与模型预测相似，心理物理学结果表明，人类观察者只需刺激的完整空间配置就能辨别点光行走者的朝向。相比之下，运动方向辨别需要刺激的完全完整的时空模式。模型中的激活水平预测了空间和时间操纵所观察到的事件相关电位。
