Paradox and Cross Purpose in Recent Work on Consciousness

1. Paradox and Cross Purpose in Recent Work on Consciousness Ned Block Presented by Allen Houng

2. 本文主旨 • Ned Block想要論證在認知神經科學關於意識的許多研究其實是處理了三種不同的意識概念：Phenomenality, Accessibility, and Reflexivity • Ned Block用概念分析與實驗證據來支持這三種不同的意識概念

3. The Paradox of Recent Finding about Consciousness Activation of ventral stream pathway NCC Presence of Consciousness Absence of Consciousness • Kanwisher (2001) • Conscious perception of faces correlate with FFA • Conscious perception of houses correlate with PPA • Driver and Vuilleumier(2001) • Visual extinction: the ventral stream is activated for extinguished stimuli • Rees, et. al. (2000) • Visual neglect and extinction / FFA&PPA: “unseen” stimuli show activation of FFA or PPA Activation of ventral stream is correlated with both absence and presence of consciousness

4. Something (X) in addition to the activation of ventral stream pathway must playing a role • X=Activation strength? • The failure of activation strength hypothesis: • Rees, et. al. (2000) Visual extinction: extinguished face stimuli were as strong as for conscious stimuli • McGlinchey-Berroth et. al. (1993) Visual neglect: the same amount of semantic priming from both hemifields, despite the lack of awareness of stimuli in the left field

5. Kanwisher, Driver and Vuilleumier’s proposal • Activation of the ventral stream supplies the contents of consciousness • X is what makes those ventral contents conscious • X=binding perceptual attributes with a time and a place, a token event • The neural basis of X is centered in the parietal cortex

6. Dehaene and Naccache:Global neuronal workspace model

7. 雖然Kanwisher的理論比較合Ned Block的胃口，Kanwisher仍然主張global accessibility為意識的要件。 • Block區別phenomenality and global accessibility

8. Could there be ventral stream activation plus X that is not widely broadcast and therefore doesn’t deserve to be called “consciousness” in this “access” sense Kanwisher is invoking? • Block: 可以設想broadcast channel壞掉了，此時global accessiblity不存在，但是phenomenality似乎仍然存在。 • Thus, we have two distinct things: phenomenality vs. global accessibility

9. Clarification on concepts of consciousness in two types of proposals • “Ventral activation plus X” and “global neuronal workspace” are based on different concepts of consciousness • Ventral activation plus X • Phenomenality • What is the neural basis of phenomenality? • Physicalism • Global neuronal workspace • Accessibility • What makes neuronal representations available for thought, decision, reporting and control of action, the main type of access? • Functionalism

10. 號稱處理意識的實驗處理了什麼？ The “exclusion” paradigm The “false recognition” paradigm 處理 Reflexive consciousness Monitoring consciousness

11. Reflexivity and Phenomenality • Reflexivity is phenomenality plus something else (reflection; a state about phenomenality) • This opens up the conceptual possibility that in principle for phenomenality without reflexivity • Conceptually or logically: Reflexivity ≠ phenomenality • Empirically: Reflexivity?phenomenality

12. Debner and Jacoby (1994)的實驗顯示可能有fleeting phenomenal consciousness of ‘reason’ as the subject’s eyes moved from the ‘4’ to ‘5’ in ‘4reason5’

13. What is the status of the “unconscious” percept in three experiments? • Two theoretical options: • The “unconscious perceptions” are both phenomenally and reflexively unconscious (in this case, the exclusion and false recognition paradigms are about consciousness in both senses) • The “unconscious perceptions” are (fleeting) phenomenally conscious but reflexively unconscious.

14. 對ventral stream in extinction三個可能的theoretical options • The ventral stream is not activated enough for either phenomenality or reflexivity (the activation strength hypothesis is wrong) • The ventral stream is activated enough for phenomenality but that isn’t sufficient for reflexivity (and more generally, for accessibility). Something else (one of the Xs mention earlier) is required (possibly not exactly the same ingredient for both reflexivity and accessibility) • There is no phenomenality or reflexive consciousness of the extinguished stimuli, but what is missing is not activation level but something else.

15. Ned Block從Sperling’s (1960) experiment on iconic memory and Liss’s (1968) experiment來證明phenomenality不等於accessibility

16. Sperling’s (1960) experiment on iconic memory M,N,X,L M N X L R T J S K Y G B Auditory tone indicates line to be remembered Array flashed for 50 msec

17. Sperling的實驗顯示subject有phenomenal consciousness卻沒有accessibility • 因為受試者被要求報告他看到什麼，無疑的她要使用letter concept • 他可能是因為缺少attentional resources，所以沒有辦法使用letter concepts

18. Dehaene and Naccache • the subject mistake the potential phenomenality for actual phenomenality, and this yields the appearance of phenomenality without access.

19. Liss’s (1968) experiment Unmasked 9 msec stimuli (1-4 letters) Lightly masked 40 msec stimuli (1-4 letters) Ask for judgment of brightness, sharpness, contrast (P-C), and what letter they saw (R-C) The subject can report 3 of 4 of the letters The subject can only report 1 of 4 of the letters Stimuli were judged as less brighter and sharper Stimuli were judged as brighter and sharper than unmasked 9 msec stimuli Dehaene and Naccache的Refrigerator Light illusion Hypothesis不能用來解釋Liss的實驗結果，因為Sperling的實驗有要求受試者report an indicated row，但Liss的實驗沒有。因此在Liss的實驗中，沒有Refrigerator Light illusion hypothesis中所做的actual or potential phenomenology之別。所有的刺激都一一呈現給受試者看，卻仍是有phenomenality and reflexivity之別

20. Cavanagh, et. al. (1998) • The resolution of visual attention----coarser • Vision resolution---finer • 實驗： 不能被numbered，但清楚看到(有phenomenality) Not attended → No concept applied → No reflexive consciousness

21. Cavanagh的實驗證明phenomenality不等於reflexivity • 這個區別可以用經驗的方式來證實 • Infants, animals等可能是有phenomenality卻沒有reflexivity

22. Conclusion • Driver and Vuilleumire and Kanwisher的concept of consciousness是phenomenality • Dehaene and Naccache的concept of consciousness是accessibility • Jack and Shallice的concept of consciousness是reflexivity • X是什麼?至今尚無解