Visual perception.ppt

1、Organizational Processes in Perception,Attentional process Principles of perceptual grouping知覺組織原則 Spatial and temporal intergration 空間上和時間上的整和 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目的指向選擇: 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刺激驅動捕獲: 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過濾理論：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 雙耳分聽 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知覺的組織原則: the tendency to integrate perceptual elements into meaningful patterns. Gestalt psychology格式塔心理學 Other Gestalt rules for organization,Gestalt psychology格式塔心理學,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連續(xù)性原則: experience lines as continuous even if they are interrupted Closure閉合原則: people will fill in missing gaps to experience objects as a whole. common fate共同命運原則: people group objects that

11、 appear to be moving in the same direction.,Motion perception,物體的運動特性直接作用于人腦 ,為人們所認識,即使運動知覺. Real movement 真正運動 Apparent movement 似動( 似動是指在一定的時間和空間條件下，人們在靜止的物體間看到了運動，或者在沒有連續(xù)位移的地方，看到了連續(xù)的運動。）,Motion perception,The autokinetic effect自主運動 : the tendency to perceive a stationary point of light in a dark

12、room as moving. Stroboscopic motion動景運動: a visual illusion in which the perception of motion is generated by a series of stationary images that are presented in rapid succession.當兩個刺激物按一定空間間隔和 時間距離相繼呈現(xiàn)時，我們會看到從一個刺激物向 另一個刺激物的連續(xù)運動。,Motion perception,The phi phenomenon PHI現(xiàn)象: a movement illusion caused

13、by successively turning on and off two separate lights. 指物體本身并未 移動，而只因物體在視網膜上的影像連續(xù)閃動而造成的運動知覺現(xiàn)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 雙眼線索 Monocular cues單眼線索 Motion cues 運動線索 Pictorial cues 圖形線索,Binocular depth cues,Retinal disparity 視網膜像差is the displacement between horizontal positions of corre

15、sponding images in the two eyes.一個物體在兩眼中對應的圖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雙眼線索 :,Experiment,Binocular depth cues,Binocular Depth Cues雙眼線索 : Convergence視軸輻合 the degree to which the eyes turn inward to focus on an object.,Monocular depth cues,Monocular depth cues單眼線

17、索 Depth cues that can be perceived by only one eye Types of cues Pictorial cures Perspective線條透視 Relative size對象的相對大小 Clearness空氣透視 Interposition遮擋 Shadowing陰影 Texture gradient結構級差 Motion cues Motion parallax運動視差,Motion cues,Motion cues 運動線索 Motion cues including relative motion parallax相對運動視差 (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(遮擋）：opaque objects block objects farther away in our visual field,Monocular depth cues,Relative image size（對象的相對大小）：A closer object will project a

19、 larger image than a more distant one (size/distance relation).,Monocular depth cues,Linear perspective (線條透視): 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(結構級差

20、）provide depth cues because the density of a texture becomes grater as a surface recedes in depths. 結構級差能夠提供深度線索是因為隨著表面深度增加，質地的密度會變大。,Monocular depth cues,Clearness(空氣透視）：perceiving objects with greater detail as being closer to us.,Monocular depth cues,Shadowing(陰影）：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 是指個體對信息進行加工時，先從物理 刺