運動知覺 （ Perceiving movement ）

1. Chapter 8 運動知覺（Perceiving movement）

2. 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

3. 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

4. Fig. 9-1, p. 196

5. Fig. 9-1a, p. 196

6. 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 • Wertheimer • Phi phenomenon • Magni-phi • AM-illusory contour

7. Fig. 9-1b, p. 196

8. (No motion)

9. 產生運動知覺的四種方式？ • 與視覺似動運動相近 • 刺激皮膚產生似動運動時，somatosensory cortex之神經元也產生反應 皮質處理感官訊息時，不論何種感官，均傾向將連續的刺激連結起來

10. 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

11. 觸覺的似動運動

12. 產生運動知覺的四種方式？ • 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）

13. Fig. 9-1c, p. 196

14. motion illusion

15. 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.

16. Fig. 9-5, p. 199

17. Fig. 9-3a, p. 198

18. Fig. 9-3b, p. 198

19. Fig. 9-3c, p. 198

20. 觀看者運動或不運動的幾種狀況 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.

21. Motion of a Stimulus Across the Retina • Aperture problem • Activity of a single complex cell does not provide accurate information about direction of movement.

22. Figure 8.12 “Movement of Bar Across an Aperture” demonstration. See text for details.

23. 框架問題（the aperture problem）

24. 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.

25. 解決方式—統整不同區域的訊息 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. Module for movement perception

26. 運動知覺的特徵偵測器 • V1複雜細胞之tuning curve • 但是神經元是如何偵測運動的？背後的神經迴路是什麼？

28. 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 structurealso 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

29. Coherence of dot movement↑, • Firing of the MT neurons↑ & Judgment of movement accuracy↑

30. 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

31. 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

32. 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.

34. 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.

35. 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.

36. Fig. 9-10, p. 203

37. 沒有IMS，但CDS引發運動知覺的可能方式 – 這些行為證據支持corollary discharge theory

38. 真實運動神經元 當眼球與刺激都運動時就不活躍 Fig. 8.23, p. 191

39. 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

40. 生物運動（biological motion） http://www.biomotionlab.ca/Demos/BMLwalker.html Fig. 9-17, p. 208

41. 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.

42. Biological motion Scrambled 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 + noise Biological motion + noise Biological motion stimulus 

43. Other neurons respond to point light walker • Also, for human, PET activity increases in STS when presented with man walking

44. 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）

45. 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）

46. 「遮蔽」經驗法則 • 運動的物體落於同一位置時可能會被遮蔽 • Duck demo

47. Finger demo

48. Fig. 9-22a, p. 210

49. Fig. 9-22b, p. 210

50. Implied motion • Representational momentum