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Chapter 8. 運動知覺 ( Perceiving movement ). 運動知覺有多重要? 運動失認症( motion agnosia ) 無法用茶壺倒茶 無法待在人多的地方 過馬路有困難. 產生運動知覺的四種方式?. 真實運動 閾值受周邊因子影響. 1/6~1/3 VA / second. 1/60 VA / second. Fig. 9-1, p. 196. Fig. 9-1a, p. 196. 產生運動知覺的四種方式?. 似動運動( apparent motion ) Exner (1875) 電影 / 動畫 / 霓虹燈 - PowerPoint PPT Presentation
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• 似動運動( apparent motion )– Exner (1875)– 電影 / 動畫 / 霓虹燈– Wertheimer
• Phi phenomenon• Magni-phi• AM-illusory contour
產生運動知覺的四種方式?
– ISI<30ms, 無運動 -- 同時 on/offISI>30ms, 部分運動ISI>60ms, 連續運動ISI>200~300ms, 無運動 -- 先後 on/off( demo )
– 距離
• 誘發運動( induced movement )– 周遭的運動引發自身運動的錯覺
• 如,坐在靜止火車中等待會車,相鄰車廂的移動引發自身車廂移動的錯覺, demo– 運動後效( motion aftereffect )
• 如瀑布錯覺( waterfall illusion ), spiral motion after effect ( demo )
產生運動知覺的四種方式?
• Structure from motion– 透過刺激的運動,使原本不清楚的結構(形狀)變得清楚可辨
Figure 9.4 Setup similar to the one used by Wallach and O’Connell (1953) to demonstrate the kinetic depth effect.
Figure 8.8 In (a) and (b), Jeremy walks past as Maria observes him. Maria perceives him as moving in (a), when his image moves across her retina, and in (b), when his image stays fixed on her fovea. In (c), when Maria walks through the environment, she perceives the environment as stationary, even though its image is moving across her retina. The text describes how the stimulus information provided by the optic array and global flow helps determine these perceptions.
觀看者運動或不運動的幾種狀況
Motion of a Stimulus Across the Retina
• Aperture problem– Activity of a single
complex cell does not provide accurate information about direction of movement.
• Solution to aperture problem– Responses of a number
of directionally selective neurons are pooled• This may occur in the
MT cortex (the where/action stream).
– Neurons on the striate cortex respond to movement of ends of objects.
Figure 9.15 (a) Some of the nuclei in the dorsal and ventral streams. The MT cortex, which is a module for movement perception, is in the dorsal stream, and the IT cortex, which is a module for form perception, is in the ventral stream. (b) The location of the MT and IT cortex in the brain.
解決方式—統整不同區域的訊息Module for movement perception
• 偵測以後呢?– MT--90% 神經元具有方向選擇性,切除之影響猴子對運動方向的偵測;方位選擇性並具有 columnar structure
also 可由 microstimulation 的方法獲得類似結論– MT 神經元並與 global motion 的偵測有關
• 相關 0.8%-- baseline firing—chance detection相關 12.8%--faster firing—highly accurate detection
• Lesioning experiment– Normal monkeys can detect motion
with coherence of 1 or 2%.– Monkeys with lesions in MT cortex
cannot detect motion until the coherence is 10 to 20%.
• Activating “preferred downward direction neurons” made monkey change judgment.
• Downward + Rightward
眼球移動的角色Corollary discharge theory
• 運動知覺仰賴三種訊號– 動作訊號( motor signal, MS )– 附帶釋放訊號( corollary discharge signal, CDS )– 影像移動訊號( image movement signal, IMS )
• 當 CDS 或 IMS 到達比較器( comparator )時,運動知覺產生;但是當 CDS 與 IMS 同時到達比較器( comparator )時,沒有運動知覺
Figure 8.18 According to the corollary discharge model (a) when a motor signal (MS) to move the eyes is sent to the eye muscles, so the eye can follow a moving object, there is a corollary discharge signal (CDS), which splits off from the motor signal. (b) When the CDS reaches the comparator, it sends a signal to the brain that the eye is moving, and motion is perceived.
Figure 9.8 How inputs to the comparator (circle) affect movement perception. When the comparator receives either the corollary discharge signal (CDS) alone, as in (a), or the image movement signal (IMS) alone, as in (b), it sends a movement signal to the cortex, and movement is perceived. When the comparator receives both the CDS and IMS signals, a movement signal is not sent to the cortex, and no movement is perceived.
Figure 9.9 In all four examples shown in the figure, a signal is sent to the eye muscles, and a corollary discharge is generated. However, no image movement signal is generated, so movement is perceived. See text for details.
知覺組織與運動知覺• 運動造成知覺組織
– Biological motion• animal• male vs. female• Neurons in monkey’s
superior temporal sulcus respond to man walking forward but less so for other directions of walking
Figure 9.18 Frames from the stimuli used by Grossman and Blake (2001). (a) Sequence from the point-light walker stimulus. (b) Sequence from the scrambled point-light stimulus.
• Determining whether motion was biological or scrambled– Noise added led to 71%
accuracy.– Transcranial magnetic
stimulation (TMS) applied only to STS caused a decrease in ability to detect biological motion.
Biological motion Scrambled stimulus
Biological motion + noise
Biological motion + noise
Biological motion stimulus
• Other neurons respond to point light walker
• Also, for human, PET activity increases in STS when presented with man walking
• 意義與運動知覺– 意義影響運動知覺 start– 知識影響運動知覺
• 最短路徑規範( shortest path constraint )–即使兩個刺激的運動路徑有很多可能性,運動知覺仍會採最短的路徑– 長 SOA(>200 ms )正常動作 start
短 SOA(<200 ms) 不可能動作 start– PET 研究發現,二者都有頂葉激發,但只有前者有運動皮質的激發
• 顯示–視覺系統需要時間來處理複雜意義的刺激–人體有其特殊性(用其他類型刺激無法得到這個結果)
運動知覺的智慧• Visual heuristics, again
– 由於視覺刺激中的訊息往往不夠明確,所以視覺系統採用一些捷徑來解讀刺激的特性• 「運動朝同一方向進行」經驗法則
–一個物體開始運動後會持續朝同一方向運動(格式塔定律 --good continuation )
Figure 8.28 Stimuli used by Reed and Vinson (1996) to demonstrate the effect of experience on representational momentum. In this example, the test pictures are lower than the memory picture. On other trials the rocket would appear in the same position as or higher than the memory picture.
Figure 9.12 Stimuli used to study the neural response to movement: (a) oriented moving bars; (b) fields of moving dots.
Figure 9.15 (a) Some of the nuclei in the dorsal and ventral streams. The MT cortex, which is a module for movement perception, is in the dorsal stream, and the IT cortex, which is a module for form perception, is in the ventral stream. (b) The location of the MT and IT cortex in the brain.
解決方式—統整不同區域的訊息Module for movement perception
• 偵測以後呢?– MT--90% 神經元具有方向選擇性,切除之影響猴子對運動方向的偵測;方位選擇性並具有 columnar structure
also 可由 microstimulation 的方法獲得類似結論– MT 神經元並與 global motion 的偵測有關
• 相關 0.8%-- baseline firing—chance detection相關 12.8%--faster firing—highly accurate detection
知覺組織與運動知覺• 運動造成知覺組織
– Biological motion• animal• male vs. female• Neurons in monkey’s
superior temporal sulcus respond to man walking forward but less so for other directions of walking
Figure 9.18 Frames from the stimuli used by Grossman and Blake (2001). (a) Sequence from the point-light walker stimulus. (b) Sequence from the scrambled point-light stimulus.
• Other neurons respond to point light walker
• Also, for human, PET activity increases in STS when presented with man walking
• 意義與運動知覺– 意義影響運動知覺 start– 知識影響運動知覺
• 最短路徑規範( shortest path constraint )–即使兩個刺激的運動路徑有很多可能性,運動知覺仍會採最短的路徑– 長 SOA(>200 ms )正常動作 start
短 SOA(<200 ms) 不可能動作 start– PET 研究發現,二者都有頂葉激發,但只有前者有運動皮質的激發
• 顯示–視覺系統需要時間來處理複雜意義的刺激–人體有其特殊性(用其他類型刺激無法得到這個結果)
運動知覺的智慧• Visual heuristics, again
– 由於視覺刺激中的訊息往往不夠明確,所以視覺系統採用一些捷徑來解讀刺激的特性• 「運動朝同一方向進行」經驗法則
–一個物體開始運動後會持續朝同一方向運動(格式塔定律 --good continuation )
Figure 9.24 Stimuli used by Reed and Vinson (1996) to demonstrate the effect of experience on representational momentum. See text for details.