视觉运动追踪的加工过程

视觉运动追踪是运动知觉研究的一个重要领域。通过构建视觉运动追踪的过程模型和分析每个阶段的认知加工任务, 可以帮助人们认识运动物体识别的本质。视觉运动追踪包括目标获取和运动追踪两个加工过程：目标获取阶段的主要任务是将目标与背景分离, 集中注意力加工追踪目标; 运动追踪阶段的主要任务是启动平滑追踪眼动和追赶性眼跳, 并发挥行为水平、眼动水平和神经活动水平的预测机制。目标获取同时受背景和目标的运动特征和身份特征影响; 运动追踪系统发挥预测机制的基础是客体表征连续性, 而客体表征连续性的建立同时依赖于目标时空属性和身份特征的编码加工。因此, 视觉运动追踪是视觉系统对客体运动信息和身份语义信息整合的结果。其中, 客体运动信息的加工特性已经获得了比较广泛的研究, 而语义信息加工机制还有待进一步加强。     

质量表征和眼动过度追踪对表征动量的影响

人们对运动目标最终位置的记忆常常会向运动方向发生偏移, 这种偏移被称为“表征动量”。现有研究对表征动量的解释涉及从低水平的知觉加工到高水平的认知加工等多个方面。本研究采用不同材质和滚动声音的球体作为刺激材料, 考察高水平的质量表征对表征动量的影响以及知觉水平的眼动信息在其中的作用。实验1探讨了对目标质量的主观表征对眼动追踪和表征动量的影响。结果显示, 质量表征会同时影响眼动追踪和表征动量。实验2通过不同的提示线索控制眼动追踪, 进一步探讨眼动过度追踪对表征动量的影响。我们发现, 非自然追踪的条件下, 表征动量会减小, 且质量表征对表征动量的影响不再显著。本研究结果表明, 高水平的质量表征对表征动量的影响会通过知觉水平的眼动过度追踪起作用; 然而, 表征动量还受其它因素影响, 眼动信息并非决定表征动量的唯一因素。     

目标刺激运动特征对自闭症谱系障碍儿童平滑追踪眼动的影响

选取3~5岁自闭症谱系障碍儿童(Autism Spectrum Disorder,ASD)与正常儿童各18名,采集其观看目标刺激沿不同垂直幅度、水平速度正弦曲线运动视频的眼动数据,考察振幅、速度等目标运动特征对被试平滑追踪眼动的影响。结果发现:(1)ASD儿童平滑追踪目标刺激的视觉位置误差显著大于正常儿童,其追踪目标的眼动轨迹不如正常组儿童平滑均匀,平滑追踪眼动存在明显不足。(2)正常儿童追踪目标刺激大振幅运行的位置误差显著大于小振幅运行条件,但ASD儿童却与之相反。(3)与正常儿童一样,目标刺激运行速度越快,ASD儿童平滑追踪的位置误差越大。总之,ASD儿童存在平滑追踪能力的不足;相比追踪大振幅运动的目标,ASD儿童追踪小振幅运动目标的能力更差。     

多目标视觉追踪中物体属性加工的眼动研究*

采用多目标视觉追踪任务(MOT),探讨物体颜色特征对视觉追踪的影响,同时记录被试的眼动情况,探讨追踪过程中颜色特征对眼动模式的影响。结果发现,视觉追踪机制能够对物体的颜色特征进行加工,但加工程度受制于目标物与分心物之间的特征竞争关系。在物体颜色特征条件下,视觉系统采用知觉组织加工策略,以被追踪目标构成的多边形中心为注意中心。在对物体颜色特征的加工中,内源性注意与外源性注意相互影响。     

目标大小变化对多目标视觉追踪的影响

采用多目标追踪任务（MOT）对追踪过程中被试（16名）的眼动进行记录,探讨目标特征变化对视觉追踪的影响。结果表明：视觉追踪机制能够对物体的特征属性进行编码加工,但加工程度受制于目标物与分心物之间的特征竞争关系;追踪过程中,视觉系统采用知觉组织加工策略,以被追踪目标构成的多边形中心为注意中心;物体大小特征没有引起较多的外源性注意,在物体大小特征的变化条件下,视觉追踪主要是内源性的注意控制加工过程。     

视觉搜索中多目标追踪的研究

在视觉信息的选择加工过程中 ,只有很少信息能够通过注意系统得到进一步的认知加工 ,其中视觉搜索起着十分重要的作用。本研究基于动态视觉信息注意追踪的研究 ,采用 3× 2× 2的实验设计 ,从如下三方面对注意追踪的规律进行了探讨 :(1)分心物数量 (1,5和 9)的变化对多目标注意追踪的影响 ;(2 )目标的显著性 (特征变化和特征不变 )对多目标注意追踪的影响 ;(3)目标运动形式 (目标随机运动和目标运动形式不变 )对多目标注意追踪的影响。研究结果表明 :(1)分心物数量的增加对目标的注意识别没有抑制作用 ;(2 )特征变化目标的注意识别速度显著高于特征不变的目标 ;(3)运动形式不变的目标较运动形式变化目标的注意识别速度快。     

代数应用题视觉化表征的理论模型及影响因素

视觉化表征是代数应用题表征的一大类型, 在问题解决过程中起着重要作用。视觉化表征的理论主要有视觉-逻辑二维模型、理解-转换模型、表象表征理论和图式-图像表征论, 四种理论模型各有其特殊的方法学意义。代数应用题的视觉化表征主要受到题目视觉化程度和认知负载等刺激因素以及自我效能感等认知因素的影响, 最后, 本文指出了在代数应用题视觉化表征理论、研究方法和影响因素探索中的进步以及发展空间。     

听觉诱发表象的眼动机制

视觉心理表象是一种基于过去经验的自上而下的加工过程,它是信息表征的一种形式.以往的研究主要采用视觉来诱发表象,但是这很难排除视觉后像的干扰,而且与表象“自上而下”的加工过程不一致.听觉诱发表象很好地解决了视觉后像的干扰问题,也更吻合表象“自上而下”的加工过程,因为被试产生的表象是基于自己过去的经验,从自身出发,主动加工的结果.采用实验法,考察通过听觉通道诱发表象眼动的情况,使用眼动仪记录被试的眼动轨迹.结果发现：（1）不管是运动还是静止的物体,都能诱发表象,在表象时存在眼动行为.（2）运动的物体诱发眼动的程度更大.（3）眼动影响表象的建构,在表象建构中起机能性作用.     

平滑追随眼动的神经机制综述

平滑追随眼动作为视觉引导的眼动行为之一,是指为保障对运动目标的精细觉察,眼睛追随慢速运动的目标以使其处于中央凹位置时眼球的运动情况。本文简要归纳介绍了平滑追随眼动的实验范式、测量指标和影响因素,在此基础上重点详述了平滑追随眼动的皮质-脑桥-小脑神经通路,其中皮质区的额眼区、辅眼区、颞中区、内侧上颞区及侧顶区在平滑追随眼动的产生中具有不同作用;而脑桥核和脑桥被盖网状核作为中继站负责将来自顶枕区和额叶区信号传递到小脑中参与眼动的区域;小脑的绒球和副绒球及蚓体负责处理平滑追随的眼动信号,并协调前庭神经反射。对平滑追随眼动的理解不仅可以帮助我们区分眼动的正常与否,发挥其临床诊断和药理学评估的作用,而且有助于确定患者大脑器质性病变或损伤的程度,同时为进一步的实验认知研究和验证提供理论基础。     

物体相似性对空间表征的影响：来自眼动的证据

以三维场景图片为实验材料,采用眼动追踪技术,通过两个实验考察了对称场景中物体相似性对空间表征的影响。结果表明：（1）无相似物体条件下,场景本身的内在结构对空间表征有重要影响,对称轴方向可以作为空间表征参照方向;（2）存在部分相似物体条件下,物体的相似性会影响空间表征参照方向的选择,并且相似物体方向也是空间表征的参照方向之一。     

Reliability of a portable head-mounted eye tracking instrument for schizophrenia research

Smooth pursuit eye movement (SPEM) abnormalities are some of the most consistently observed neurophysiological deficits associated with genetic risk for schizophrenia. SPEM has been traditionally assessed by infrared or video oculography using laboratory-based fixed-display systems. With growing interest in using SPEM measures to define phenotypes in large-scale genetic studies, there is a need for measurement instruments that can be used in the field. Here we test the reliability of a portable, head-mounted display (HMD) eye movement recording system and compare it with a fixed-display system. We observed comparable, modest calibration changes across trials between the two systems. The between-methods reliability for the most often used measure of pursuit performance, maintenance pursuit gain, was high (ICC = 0.96). This result suggests that the portable device is comparable with a lab-based system, which makes possible the collection of eye movement data in community-based and multicenter familial studies of schizophrenia.     

Initial scene representations facilitate eye movement guidance in visual search

What role does the initial glimpse of a scene play in subsequent eye movement guidance? In 4 experiments, a brief scene preview was followed by object search through the scene via a small moving window that was tied to fixation position. Experiment 1 demonstrated that the scene preview resulted in more efficient eye movements compared with a control preview. Experiments 2 and 3 showed that this scene preview benefit was not due to the conceptual category of the scene or identification of the target object in the preview. Experiment 4 demonstrated that the scene preview benefit was unaffected by changing the size of the scene from preview to search. Taken together, the results suggest that an abstract (size invariant) visual representation is generated in an initial scene glimpse and that this representation can be retained in memory and used to guide subsequent eye movements.     

Further experiments on movement masking

Voluntary attention to one of two static objects in the peripheral field of one eye makes this object more liable to masking by a moving object in the corresponding area of the field of the other eye (Experiment 1).

Positive after images (and probably negative after images) are subject to (binocular) movement masking (Experiment 2).

Movement masking can occur in the field of either eye, but with the displays so far tried the inhibitory influence of a moving object is less in the field of the eye to which it is shown than in the field of the other eye (Experiment 3).     

Our Eyes Do Not Always Go Where We Want Them to Go: Capture of the Eyes by New Objects

Observers make rapid eye movements to examine the world around them. Before an eye movement is made, attention is covertly shifted to the location of the object of interest. The eyes typically will land at the position at which attention is directed. Here we report that a goal-directed eye movement toward a uniquely colored object is disrupted by the appearance of a new but task-irrelevant object, unless subjects have a sufficient amount of time to focus their attention on the location of the target prior to the appearance of the new object. In many instances, the eyes started moving toward the new object before gaze started to shift to the color-singleton target. The eyes often landed for a very short period of time (25–150 ms) near the new object. The results suggest parallel programming of two saccades: one voluntary, goal-directed eye movement toward the color-singleton target and one stimulus-driven eye movement reflexively elicited by the appearance of the new object. Neuroanatomical structures responsible for parallel programming of saccades are discussed.     

A revised analysis of the role of efference in motion perception

The analysis of motion perception historically has included efferent as well as afferent mechanisms to account for the perception of motion during eye movement. The application of efferent mechanisms to motion perception has been limited, however, by several illusions which are apparently inconsistent with the notion that oculomotor mechanisms contribute to motion perception. An alternative account is presented of the manner in which efference may contribute to the perception of motion. It is proposed that distinct smooth eye-movement systems contribute differentially to object motion perception. Specifically, activity in the smooth pursuit system gives rise to the perception of object motion, whereas activity in the smooth component of reflexive eye movements does not. Tracking of a moving object results in object motion perception as a result of efference in the pursuit system. However, the pursuit system may be activated to oppose the smooth component of reflexive eye movements in order to preserve fixation on a stationary object. In such cases neither the fixated object nor the eye is moving but illusory movement results from the efference in the pursuit system. A number of illusory movement phenomena are interpreted in terms of this model.     

An Ecological Approach to Modeling Vision: Quantifying Form Perception Using the Circle Map Equation

Abstract

Object perception occurs within a dynamic world, where the environment and the observer (both body and eyes) are continually moving, shifting and changing. We seek to characterize and quantify this process from a perspective accounting for the interconnected system of motion in the environment, the perceiver and the eye, unfolding through time. Specifically, we build a mathematical representation for object perception based off the circle map equation. We describe an interaction between the eyes’ movement and the movement in the world, in order to better understand how those work together to result in perception. Across three experiments, we show that the stability of the relationship between object perception and complex eye movements can be perturbed and will have a predictable response to said perturbations. In so doing, we provide a different context – a dynamical systems framework – under which we can begin to consider the ecological validity of visual perception models, while recognizing the degree to which the visuo-spatial world is continuously being perturbed and disrupted. In fact, we postulate that such perturbations are capitalized on by the perceptual system, contributing to accurate object and motion identification.     

The pop out of scene-relative object movement against retinal motion due to self-movement

An object that moves is spotted almost effortlessly; it "pops out". When the observer is stationary, a moving object is uniquely identified by retinal motion. This is not so when the observer is also moving; as the eye travels through space all scene objects change position relative to the eye producing a complicated field of retinal motion. Without the unique identifier of retinal motion an object moving relative to the scene should be difficult to locate. Using a search task, we investigated this proposition. Computer-rendered objects were moved and transformed in a manner consistent with movement of the observer. Despite the complex pattern of retinal motion, objects moving relative to the scene were found to pop out. We suggest the brain uses its sensitivity to optic flow to "stabilise" the scene, allowing the scene-relative movement of an object to be identified.     

Increased saccadic rate during smooth pursuit eye movements in patients at Ultra High Risk for developing a psychosis

Abnormalities in eye tracking are consistently observed in schizophrenia patients and their relatives and have been proposed as an endophenotype of the disease. The aim of this study was to investigate the performance of patients at Ultra High Risk (UHR) for developing psychosis on a task of smooth pursuit eye movement (SPEM). Forty-six UHR patients and twenty-eight age and education matched controls were assessed with a task of SPEM and psychiatric questionnaires. Our results showed that both the corrective and non-corrective saccadic rates during pursuit were higher in the UHR group. There were however no differences in smooth pursuit gain between the two groups. The saccadic rate was related to positive UHR symptoms. Our findings indicate that abnormalities in SPEM are already present in UHR patients, prior to a first psychotic episode. These abnormalities occur only in the saccadic system.     

Movement prediction and movement production

The prediction of future positions of moving objects occurs in cases of actively produced and passively observed movement. Additionally, the moving object may or may not be tracked with the eyes. The authors studied the difference between active and passive movement prediction by asking observers to estimate displacements of an occluded moving target, where the movement was driven by the observer's manual action or was passively observed. In the absence of eye tracking, they found that in the active condition, estimates are more anticipatory than in the passive conditions. Decreasing the congruence between motor action and visual feedback diminished but did not eliminate the anticipatory effect of action. When the target was tracked with the eyes, the effect of manual action disappeared. Results indicate distinct contributions of hand and eye movement signals to the prediction of trajectories of moving objects.