Visual perception.ppt

1、Organizational Processes in Perception,Attentional process Principles of perceptual grouping知觉组织原则 Spatial and temporal intergration 空间上和时间上的整和 Motion perception Depth perception perceptual constancies,Organizational Processes in Perception,The processes that put sensory information together to give

2、 you the perception of coherence are referred to collectively as processes of perceptual organization.,Attentional process,The more closely you attend to some object or event in the environment, the more you can perceive and learn about it.,Determining the focus of our attention,Goal-directed select

3、ion目的指向选择: reflects the choices that you make about the objects to which youd like to attend, as a function of your own goals. Stimulus-driven capture刺激驱动捕获: occurs when features of the stimuli-objects in the environment-themselves automatically capture your attention, independent of your local goal

4、.,Research suggests that stimulus-driven capture wins out over goal-directed attention.,The fate of unattended information,David Broadbent suggested that the mind has a limited capacity to process information in our environment. Thus, attention functions to restrict and regulate information that flo

5、ws into our awareness. Filter Theory过滤理论：attests that selection of attention occurs early in the process, prior to the meaning or interpretation of the object being processed.,The fate of unattended information,Dichotic listening experiments 双耳分听 different auditory stimuli are presented to each ear,

6、 was used to test the filter theory. The research subject is instructed to repeat only one of the two messages presented (a procedure called shadowing the attended message).,The fate of unattended information,Filter Theory was challenged by cocktail party phenomenon.,Principles of Perceptual groupin

7、g,Principles of Perceptual grouping知觉的组织原则: the tendency to integrate perceptual elements into meaningful patterns. Gestalt psychology格式塔心理学 Other Gestalt rules for organization,Gestalt psychology格式塔心理学,It was prominent in Germany in the 1920s. Three founders- Max Werthimer (1880-1943),Kurt koffka(1

8、886-1941),and Wolfgang Kohler(1887-1967). Gestalt - means “whole” or good form psychological phenomena are understood only when they are organized into a unified whole, not as individual perceptual elements.,Figure-ground perception,Figure: objects in our visual field that are organized to be distin

9、guished from a collection of background objects. Ground: background areas of the visual field. Figure has a shape, the ground does not Figure is close, ground is far away Figure is dominant and remembered better,Other Gestalt laws for organization,Proximity接近律: people group stimuli together into the

10、 nearest proximal elements Similarity相似律: people group information into the most similar elements. Continuity连续性原则: experience lines as continuous even if they are interrupted Closure闭合原则: people will fill in missing gaps to experience objects as a whole. common fate共同命运原则: people group objects that

11、 appear to be moving in the same direction.,Motion perception,物体的运动特性直接作用于人脑 ,为人们所认识,即使运动知觉. Real movement 真正运动 Apparent movement 似动( 似动是指在一定的时间和空间条件下，人们在静止的物体间看到了运动，或者在没有连续位移的地方，看到了连续的运动。）,Motion perception,The autokinetic effect自主运动 : the tendency to perceive a stationary point of light in a dark

12、room as moving. Stroboscopic motion动景运动: a visual illusion in which the perception of motion is generated by a series of stationary images that are presented in rapid succession.当两个刺激物按一定空间间隔和 时间距离相继呈现时，我们会看到从一个刺激物向 另一个刺激物的连续运动。,Motion perception,The phi phenomenon PHI现象: a movement illusion caused

13、by successively turning on and off two separate lights. 指物体本身并未 移动，而只因物体在视网膜上的影像连续闪动而造成的运动知觉现象。 This phenomenon occurs when two stationary spots of light in different positions in th visual field are turned on and off alternately at a rate of about four to five times per second.,Depth perception,Ima

14、ge on retina is flat and 2D, how do we perceive depth and 3D? Using visual cues to estimate depth and distance of objects. Binocular cues 双眼线索 Monocular cues单眼线索 Motion cues 运动线索 Pictorial cues 图形线索,Binocular depth cues,Retinal disparity 视网膜像差is the displacement between horizontal positions of corre

15、sponding images in the two eyes.一个物体在两眼中对应的图像在水平方向上的位移 Because there is a certain distance between the eyes, a slightly different image reaches each retina. The brain then integrates these two images into one composite view. But it does not ignore the difference in images, which is known as binocula

16、r disparity. The disparity allows the brain to estimate the distance of an object from us,Binocular Depth Cues双眼线索 :,Experiment,Binocular depth cues,Binocular Depth Cues双眼线索 : Convergence视轴辐合 the degree to which the eyes turn inward to focus on an object.,Monocular depth cues,Monocular depth cues单眼线

17、索 Depth cues that can be perceived by only one eye Types of cues Pictorial cures Perspective线条透视 Relative size对象的相对大小 Clearness空气透视 Interposition遮挡 Shadowing阴影 Texture gradient结构级差 Motion cues Motion parallax运动视差,Motion cues,Motion cues 运动线索 Motion cues including relative motion parallax相对运动视差 (as y

18、ou move, objects closer to you appear to move faster than distant ones) assist in our perception of distance or depth.,Monocular depth cues,Interposition(遮挡）：opaque objects block objects farther away in our visual field,Monocular depth cues,Relative image size（对象的相对大小）：A closer object will project a

19、 larger image than a more distant one (size/distance relation).,Monocular depth cues,Linear perspective (线条透视): Linear perspective occurs when parallel lines appear to converge in the distance. Our perception of converging lines leads to the Ponzo illusion.,Monocular depth cues,Texture gradient(结构级差

20、）provide depth cues because the density of a texture becomes grater as a surface recedes in depths. 结构级差能够提供深度线索是因为随着表面深度增加，质地的密度会变大。,Monocular depth cues,Clearness(空气透视）：perceiving objects with greater detail as being closer to us.,Monocular depth cues,Shadowing(阴影）：perceiving shadows and highlight

21、s as giving depth to two-dimensional objects.,Monocular depth cues,Psychological cues are learned cues, therefore, they are assisted by experience. When combined, these cues enhance depth perception greatly,Perceptual constancies,you see the world as invariant,constant, and stable despit changes in

22、the stimulation of your sensory receptors. Psychologists refer to this phenomenon as perceptural constancy.,Size constancy,Size constancy refers to your ability to perceive the true size of an object despite variations in the size of its retinal image.,Size constancy,If the size of an object is perc

23、eived by taking distance cues into account, then you should be fooled about size whenever you are fooled about distance. Ames room,Size constancy,Another way that the perceptual system can infer objective size is by using prior knowledge about the charcateristic size of similarly shaped objects.,lig

24、htness constancy,Lightness constancy is your tendency to perceive the whiteness, grayness, or blackness of objects as constant across changing levels of illumination .,Identification and recognition process,Bottom-up and top-down processes The influnce of contexts and expectation,Top-down versus bottom-up processing.,Bottom - up process is data driven, whereas sensory information from the environment is passed upward toward more abstract representations. 自下而上加工 是指个体对信息进行加工时，先从物理 刺