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Chapter 6

Chapter 6. Visual Attention. 注意力對於知覺是必要的嗎？ 注意力可以促進知覺表現嗎？. Fig. 6-CO, p. 120. 選擇性注意力（ selective attention ）. 注意某些刺激而忽略其他的 眼動（ eye movement ）是一個基本的選擇機制，但眼動並非選擇性注意力的必要條件

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Chapter 6

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  1. Chapter 6 Visual Attention

  2. 注意力對於知覺是必要的嗎？ • 注意力可以促進知覺表現嗎？ Fig. 6-CO, p. 120

  3. 選擇性注意力（selective attention） • 注意某些刺激而忽略其他的 • 眼動（eye movement）是一個基本的選擇機制，但眼動並非選擇性注意力的必要條件 • William James (1890)Millions of items…. Are present to my senses which never properly enter my experience. Why? Because they have no interest for me. My experience is what I agree to attend to……Everyone knows what attention is. It is the taking possession by the mind, in clear an vivid form, of one out of what seem several simultaneously possible objects or trains of thought…….It implies withdrawal from some things in order ot deal effectively with others.

  4. 由眼動瞭解選擇性注意力 • Saccades • Fixation(1st)

  5. Fig. 6-4, p. 124

  6. Bottom-up control of selective attention • stimulus salience (defined by color, contrast and orientation) • Saliency map

  7. Figure 6.5 (a) A visual scene. (b) Salience map of the scene determined by analyzing the color, contrast, orientations in the scene. Lighter areas indicate greater salience. (Reprinted from Vision Research, 42, Parkhurst, D., Law, K., & Niebur, E., Modeling the Role of Salience in the Allocation of Overt Visual Attention, 107-123 (2002).)

  8. Top-down control of selective attention • Scene schema guides fixations (more likely to land on meaningful areas) • Task goals guides fixations to land on objects relevant to the task

  9. 注意力對於知覺是有必要的嗎？ • 有必要 • Li (2002) • Ss judge if letters in the middle are the same • Ss are 76% correct on whether the scene appeared—缺乏選擇性注意力時仍可能產生某些知覺經驗 27 ms

  10. Reddy et al. (2007) • Dual task condition: face vs. red-green disc(see Fig 6.7 & 6.8) • Some types of information perceived without attention and some didn’t.

  11. 沒必要 • 不注意盲（Inattentional blindness）（Mack & Rock, 1998） Figure 6.8 Inattentional blindness experiment. (a) Participants judge whether the horizontal or vertical arm is larger on each trial. (b) After a few trials, a geometrical object is flashed, along with the arms. (c) Then the participant is asked to pick which geometrical stimulus was presented.

  12. Gorillas in our midst: Sustained inattentional blindness (Simons & Chabris, 1999) http://www.youtube.com/watch?v=nkn3wRyb9Bk Failure to detect superimposed images in a film

  13. 改變盲（change blindness ） • 顯示視覺環境中只有一小部分是被表徵的 • http://tw.youtube.com/watch?v=mAnKvo-fPs0&NR=1 • 改變偵測作業 • Change blindness blindness (Levin, 2000)

  14. Fig. 6-11, p. 128

  15. Fig. 6-10, p. 127

  16. Fig. 6-11, p. 128

  17. Fig. 6-10, p. 127

  18. Fig. 6-12, p. 128

  19. Figure 6.13 (a) Scene with blur added to simulate the decrease in visual acuity that occurs in the periphery of the visual field. The fixation point is on the woman’s face. (b) The same scene without blur. Even though our ability to see details is poor in the periphery, we generally experience the world as being “sharp” rather than blurry. (Blurring courtesy of Stuart Anstis.)

  20. 注意力可以促進知覺處理嗎？ • 注意力導向之處的知覺處理較有效率 • Precueing (cueing) task (M. Posner) • 方塊出於箭號提示側時，反應較快（凝視在中央的十字)

  21. 注意力對於知覺的促進效果以「物體」為單元而散播注意力對於知覺的促進效果以「物體」為單元而散播 • R Egly • AC=ABRTB<RTC

  22. 注意力真的能讓物體看來更「清晰」嗎？ • 注意力是促進「知覺」還是作「反應」？測量到的注意力效果反映的是什麼？ • 例如：「哪一個比較亮？」--注意力是否影響？ • 但即使如此，也有可能是來自於受試有成見認為注意的刺激會比較清楚

  23. 報告「對比較強的光柵朝向哪個方向？」（Carrasco et al., 2004） • 結果當對比其實相同時，注意側（160 ms 前閃光點）被報告的的機會增加

  24. 注意力對於特徵結合（binding）的促進 • 即便腦的不同分區處理不同的知覺層面，但主觀知覺經驗是統整的

  25. 特徵整合論（feature integration theory）(Treisman & Gelade, 1980) • 前注意（preattentive）階段分析視知覺的基本特徵，集中注意（focused attention）階段作特徵之整合以產生物體知覺 • 注意力像膠水般將what與where管道的訊息結合起來

  26. Binding需要集中注意力的證據 • 錯覺組合（illusory conjunction）(Treisman & Schmidt, 1982) MASK 200 ms 受試報告數字及每個幾何圖形 18%機會產生錯覺組合—例如報告「小的紅色圓形」

  27. 產生錯覺組合的原因是因為在快速呈現下，受試的注意力被導向數字產生錯覺組合的原因是因為在快速呈現下，受試的注意力被導向數字 • Balint’s syndrome • RM頂葉受損，無法對個別物體產生集中注意力 • 即使呈現時間很長（10 s）仍產生高比例（23%）的錯覺組合 • 視覺搜尋（visual search） • 特徵搜尋（feature search）vs. 組合搜尋（conjunction search） • 組合搜尋需要注意力參與？RM無法進行組合搜尋正常人進行組合搜尋時頂葉會激發

  28. Figure 6.22 Find the horizontal line in (a) and then in (b).

  29. Binding在神經生理層次如何進行？--同步化假設（synchrony hypothesis） • 皮質不同區域的神經元對同一物體屬性產生反應時，這些激發會同步化—以同樣型態（而非同時）產生激發 • 注意力增加同步化？ • Needs more evidence

  30. 二個狀況下網膜影像均相同，只有注意力狀況的差別二個狀況下網膜影像均相同，只有注意力狀況的差別 注意力的神經生理學 • 促進神經元的激發（Colby et al., 1995）

  31. 這種促進作用在 V1就存在，但愈高階處理區域促進作用愈強

  32. Fig. 6-26, p. 137

  33. Attention in Autism • Watched movie while eye fixations were tracked • Autistic vs. Non-autistic people • Autistic observers look at socially irrelevant stimuli in these situations.

  34. Neural Processes for Attention in Autism • Pelphrey et al. (2005) • Observers pressed a button when they saw the character’s eyes move about two conditions. • Accuracy: Nonautistic = autistic • Activation of the STS: Nonautistic ≠ autistic • Autistic people cannot read intentions of others. C = congruent condition IC = incongruent condition

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