客体运动方向的视觉工作记忆容量

记忆动态场景中多客体的特征和时空信息是人类重要的认知活动。目前有关视觉工作记忆的研究虽然广泛探讨了对视觉信息的存储容量及机制,然而所采用的刺激材料均呈现于静态场景中,且不包含运动信息。而有关多客体追踪的研究只关注动态场景中多客体信息的实时更新,而不涉及一段时间内对客体信息的保持。本研究结合视觉工作记忆领域的变化觉察范式和多客体追踪范式,以独立运动的客体为刺激材料,探讨多个客体的运动方向信息在工作记忆中的存储容量问题。结果表明,在工作记忆中能够存储大约3个客体的运动方向信息。     

Human and machine perception of biological motion

More than 30 years ago, Johansson was the first to show that humans are capable of recovering information about the identity and activity of animate creatures rapidly and reliably from very sparse visual inputs – the phenomenon of biological motion. He filmed human actors in a dark setting with just a few strategic points on the body marked by lights – so-called moving light displays (MLDs). Subjects viewing the MLDs reported a vivid impression of moving human forms, and were even able to tell the activity in which the perceived humans were engaged. Subsequently, the phenomenon has been widely studied and many attempts have been made to model and to understand it. Typical questions that arise are: How precisely is the sparse low-level information integrated over space and time to produce the global percept, and how important is world knowledge (e.g., about animal form, locomotion, gravity, etc.)? In an attempt to answer such questions, we have implemented a machine-perception model of biological motion. If the computational model can replicate human data then it might offer clues as to how humans achieve the task. In particular, if it can do so with no or minimal world knowledge then this knowledge cannot be essential to the perception of biological motion. To provide human data for training and against which to assess the model, an extensive psychophysical experiment was undertaken in which 93 subjects were shown 12 categories of MLDs (e.g., normal, walking backwards, inverted, random dots, etc.) and were asked to indicate the presence or absence of natural human motion. Machine perception models were then trained on normal sequences as positive data and random sequences as negative data. Two models were used: a k-nearest neighbour (k-NN) classifier as an exemplar of ‘lazy’ learning and a back-propagation neural network as an exemplar of ‘eager’ learning. We find that the k-NN classifier is better able to model the human data but it still fails to represent aspects of knowledge about body shape (especially how relative joint positions change under rotation) that appear to be important to human judgements.     

Infants perceive human point-light displays as solid forms

While five-month-old infants show orientation-specific sensitivity to changes in the motion and occlusion patterns of human point-light displays, it is not known whether infants are capable of binding a human representation to these displays. Furthermore, it has been suggested that infants do not encode the same physical properties for humans and material objects. To explore these issues we tested whether infants would selectively apply the principle of solidity to upright human displays. In the first experiment infants aged six and nine months were repeatedly shown a human point-light display walking across a computer screen up to 10 times or until habituated. Next, they were repeatedly shown the walking display passing behind an in-depth representation of a table, and finally they were shown the human display appearing to pass through the table top in violation of the solidity of the hidden human form. Both six- and nine-month-old infants showed significantly greater recovery of attention to this final phase. This suggests that infants are able to bind a solid vertical form to human motion. In two further control experiments we presented displays that contained similar patterns of motion but were not perceived by adults as human. Six- and nine-month-old infants did not show recovery of attention when a scrambled display or an inverted human display passed through the table. Thus, the binding of a solid human form to a display in only seems to occur for upright human motion. The paper considers the implications of these findings in relation to theories of infants' developing conceptions of objects, humans and animals.     

客体的视觉工作记忆研究进展

近年来,客体信息的视觉工作记忆问题引发了大量研究,并获得不少成果。本文对视觉工作记忆的研究范式,客体在视觉工作记忆中的存储方式、容量及保持时间等相关研究进行了概述,重点介绍关于视觉工作记忆存储单元和容量问题的"强客体"假设、"弱客体"假设和双重存储机制假设,并提出进一步的研究思路。     

面孔识别动态增益效应研究综述

近年来,研究者围绕动态面孔识别中的动态增益效应开展了一系列的研究。本文围绕面孔熟悉程度和面孔的活动类型两个方面对与动态增益效应有关的一系列动态面孔认知研究进行了总结,并对不同研究的差异进行了比较和分析。最后,对动态面孔认知规律、眼动模式和脑机制等研究方向上的发展进行了展望。     

Anticipating intentional actions: The effect of eye gaze direction on the judgment of head rotation

Using a representational momentum paradigm, this study investigated the hypothesis that judgments of how far another agent’s head has rotated are influenced by the perceived gaze direction of the head. Participants observed a video-clip of a face rotating 60° towards them starting from the left or right profile view. The gaze direction of the face was either congruent with, ahead of, or lagging behind the angle of rotation. Following this, two static faces, at varying angles of rotation with respect to the end-point angle of the face in the video-clip, were presented simultaneously. The task of the participants was to decide which of the two heads was at an angle best resembling the angle of the end-point of the moving face. The critical test condition consisted of one test face oriented at 10° before, and the other at 10° after the end-point. The ‘lagging behind’ gaze condition elicited a significant underestimation of the rotation compared to the ‘congruent’ and ‘ahead’ gaze conditions. Participants did not exhibit similar biases when judging the rotation of several non-face control stimuli with visual features that mimicked different aspects of gaze direction. The findings suggest that when the gaze direction of a perceived agent is incongruent with the direction of the agent’s head motion observers automatically utilise this discrepancy to adjust their inferences about the agent’s intended heading direction.     

Visual versus phonological abilities in Spanish dyslexic boys and girls

Phonological and visual theories propose different primary deficits as part of the explanation for dyslexia. Both theories were put to test in a sample of Spanish dyslexic readers. Twenty-one dyslexic and 22 typically-developing children matched on chronological age were administered phonological discrimination and awareness tasks and coherent motion perception tasks. No differences were found between groups on the coherent motion tasks, whereas dyslexic readers were impaired relative to controls on phonological discrimination tasks. Gender differences followed the opposite pattern, with no differences on phonological tasks, and dyslexic girls performing significantly worse than dyslexic boys in coherent motion perception. These results point to the importance of phonological deficits related to speech perception in Spanish, and to possible gender differences in the neurobiological bases for dyslexia.     

孤独症谱系障碍者的生物运动探测障碍：基于行为与神经的证据

关于孤独症谱系障碍个体探测生物运动的能力是否受损,已有行为研究尚存分歧。导致分歧的原因可能是实验刺激、实验任务和测量指标存在差异。然而,神经研究却一致证实其潜在的神经机制存在异常。领域特殊性观点认为该障碍可能是基于后侧颞上沟功能异常的社会性功能障碍,也可能是基于镜像神经元功能异常的社会性功能障碍;而领域一般性观点认为该障碍可能是基于背侧视觉流功能异常的视运动知觉障碍,也可能基于脑功能联结异常的弱中央统合障碍。据此,本文将从研究范式、行为表现及潜在机制三个方面梳理相关研究,以期为后续研究提供新方向。     

人眼深度运动知觉的研究

人类的深度运动知觉,是通过检测二维平面内的相对运动而形成的。本文在心理物理学实验基础上,揭示该机制的数学与生理学实现形式。视觉系统中存在对视平面内的相对运动敏感的神经元,构成深度运动的检测机制,产生单眼深度运动知觉与双眼深度运动知觉。在心理学上,视觉利用物体视角变化及大小知觉的恒常性判断深度运动。文中还初步讨论了人类的深度运动知觉与蜜蜂,家蝇等昆虫的深度运动知觉的区别。