Inner Speech

1. Inner Speech Michael Johnson VAP HKU

2. Outline • Two Puzzles • Separatism • Why Inner Speech? • The Computational Explanation • Conclusion

3. 1. two puzzles

4. Puzzle #1 Suppose we can think about propositions, probability distributions, and utility functions, and can compute expected utilities from them (or whatever). What does making any of these states conscious gain us? What is the purpose of conscious thought? If thinking is computational, how could something as obviously non-formal as consciousness make any difference?

5. Thinking in French In About.com’s“French Language” article, author Laura K. Lawless speaks about the virtues of daily French practice: “Thinking about French every day will help you learn how to think in French, which is a key element of fluency.” Lawless assumes a quite natural view, namely that one can think in this or that natural human language.

6. Thinking in English It seems to me, a monolingual English speaker, that whenever I’m conscious of thinking, I’m thinking in English. Sometimes I can’t find the words to express what I want to say, and there’s a ‘gap’ in the interior monologue. I suppose it’s filled with thinking—thinking of what to say—but I don’t experience that thinking. All the thinking I experience is English-thinking.

7. Thinking in Language “[A]ftermuch practice, we no longer really need to call forth a symbol, we do not need to speak out loud in order to think. The fact remains that we think in words or, when not in words, then in mathematical or other symbols. Without symbols we would further hardly raise ourselves to the level of conceptual thought.” Frege,

8. Puzzle #2 Let’s call thinking in English or French or Cantonese ‘inner speech.’ What the last observation suggests is that inner speech is the phenomenal character of thought. This itself is puzzling because we know that the language of thought is not English (or French or Cantonese). Why is thought (≠ English) experienced as English?

9. Arguments that LOT ≠ English Extensional inequivalence: • Pre-linguistic infants think (else they can’t learn languages). • Deaf adult humans who don’t know sign-language (or a spoken language) think. • Non-human animals think.

10. Arguments that LOT ≠ English Computational inadequacy: • LOT articulates elements unarticulated by English (PRO, pro, etc.) • LOT is scopally unambiguous where English is not– every thought of “Every boy loves some girl” is determinate as to the order of the quantifiers.

11. Puzzle #2 is Deeper It wouldn’t really matter if LOT were English. It would still be weird for it to have a phenomenal character similar to perceived spoken English. One way to see this is to suppose representationalism (e.g. Dretske 1997) is true. The p.c. of a conscious state = the property that state represents.

12. The Puzzle, Assuming Rep’ntationalism Then since the p.c. of perceived spoken English is roughly the same as the p.c. of inner speech, they should represent roughly the same thing. But my auditory perceptions of English represent sounds, and the vast majority of my thoughts (those not about sounds) don’t represent sounds.

13. Puzzle #2 I don’t want to assume that representationalism is true. But the assumption foregrounds a genuine oddity, no matter your theory of consciousness: thought and perception of spoken English (Cantonese/ whatever) are radically different. Why should they be phenomenally similar?

14. 2. Separatism

15. Puzzle #1 Redux Many of our perceptual states are conscious, in that they have phenomenal characters. Suppose as a result of retinal stimulation, our visual perception module can segment scenes into edges, edges into boundaries, boundaries into objects, objects into parts, etc. What does making any of these states conscious gain us?

16. Consciousness as a Free-Rider Nothing, and that’s the standard view. That these states are conscious is necessitated by their causal and representational properties (or whatever). We can’t make a state without the relevant causal/ representational properties conscious, and we can’t make a state with them non-conscious.

17. Consciousness as a Free-Rider Maybe thoughts are like perceptions. They have phenomenal characters that supervene on their causal and representational properties. Consciousness adds nothing, because consciousness cannot be added to anything.

18. An example of such a view might be Dennett [cite]. In Dennett’s view, for a state to be conscious is just for it to occupy a certain sort of influential role with respect to memory and action. Something that doesn’t occupy that role can’t be “made conscious” unless that means “made to occupy that role.” [Dennett thinks that there isn’t any phenomenal consciousness though, just access consciousness.]

19. Problem But only some very small number of thoughts are conscious. So we face a dilemma: either we reject the claim that the causal or representational properties of thoughts necessitate their having p.c.’s or we find some causal or representational difference between the conscious ones and the others. What could such a difference be? (Cf. Dennett)

20. Reason to Reject Thoughts with P.C. The conscious properties of perceptions are not affected by our past experiences. I don’t learnhow to see redness when I look at red things. But until I learn, say, French, none of my thoughts are accompanied by inner French. I can’t see “in French” but I can think “in French”.

21. Second Reason Everyone with normal, functioning sensory faculties sees/ tastes/ feels/ etc. things in much the same way. But what it’s like for me and a cognitively normal monolingual French speaker to think that it’s mom’s birthday on Tuesday is different.

22. Puzzle #2 Redux Even if we manage this dilemma, we’re still stuck with Puzzle #2. Why is the phenomenal character of thought so much like the auditory perception of English (Cantonese) utterances?

23. Separatism Separatism holds that thoughts are never conscious. What happens in the case of inner speech is that a thought causes a perceptual state, and the perceptual state is conscious (as outlined in the solution to Puzzle #1). So thinking about my mother has no p.c. but it might cause states that do, like a mental image of my mother or an auditory “image” of the word ‘mom.’

24. Evidence for Separatism The strongest evidence for separatism (with respect to thought vs. inner speech, at least) is the more-or-less complete overlap (modulo motor activation) between brain activation in speech production and brain activation in inner speech production.

25. Brain Areas Implicated in Speech • Lexical selection: left middle of temporal gyrus • Syntactic encoding: Rolandic operculum, left inferior frontal gyrus • Phonological code retrieval: right SMA, left anterior insula, middle temporal gyrus (Wernicke’s area) • Phonological encoding: the left posterior inferior frontal gyrus(Broca’s area) and the left mid superior temporal gyrus(STG)

26. The Brain and Inner Speech Importantly, in both inner speech and auditory visual imagery (imagining someone else saying something), all these brain areas are active. Many researchers (e.g. Bookheimer 2002) think the brain activity in inner speech is the same as in overt speech– just a little less strong, and minus the motor activation. (There’s equivocal evidence that some areas are differentially sensitive.)

27. Broca’s Area Finally, patients with damage to Broca’s area can suffer expressive aphasia– an inability to speak or write words. Transcranial magnetic stimulation of Broca’s area has been shown to inhibit inner speech (interferes with a covert syllable-counting task). Some evidence suggests Broca’s area is more active in inner speech than overt speech.

28. Why Inner Speech? But here’s where the current consensus ends, and problems remain unresolved. How does inner speech help? If you’re thinking in a logically perspicuous language (LOT), why go to the lengths of translating that into a less perspicuous language (English), which you then proceed to not think in? Why inner speech?

29. The Problem Let’s be clear where we are. We had a puzzle as to why thoughts are conscious in the first place, and a puzzle as to why the phenomenal character of thoughts was English (or French or whatever). Separatism has a solution to both puzzles: it denies that thoughts are conscious and maintains that the phenomenal character of inner speech is expected, given that inner speech is more-or-less auditory imagery.

30. The Problem But the analog of both puzzles reappears. Now it’s not “why is thought conscious?” but “why is unconscious thought accompanied by inner speech?” Furthermore, why is it inner speech, given that we know that English is less logically perspicuous than LOT?

31. 3. Why inner speech?

32. Three Explanations Here are three potential explanations: • There’s no benefit to inner speech, it’s a side-effect of something else. • There’s a benefit to inner speech, namely that it’s conscious whereas thought is not and cannot be (the separatist consensus). • There’s a benefit to inner speech, but one that has nothing to do w/ its consciousness.

33. Side-Effect Explanation Here’s the sort of story one might tell: for conversation, we need to translate LOT into English quickly. Maybe the mechanism that does that translates all the thoughts in the relevant buffer, without regard to whether you want to give voice to them. So when you’re sitting by yourself, that’s what you’re hearing– even though it does you no good at all.

34. Something Like This? This particular explanation won’t work (why in the world would it route them through hearing? What you need for rapid conversation is quick translation from thought to speaking.) But could something like it work?

35. Not a Side-Effect I don’t think so. There’s a fair bit of literature on the benefits gained by inner speech. They include higher self-awareness, greater intelligence, improved mathematical ability, and better memory. Inner speech is doing something. The question is how it is doing it.

36. Consciousness Explanation A second possible explanation goes something like this: “Wow, if the separatist is right, then thoughts aren’t conscious. But consciousness has all these benefits right? Like, it’s a “global workspace” that makes information available, um, globally. So we translate our thoughts into inner speech to gain the consciousness benefits inner speech has by right of its perceptual nature.”

37. Wrong Order of Explanation But this line of reasoning has the order of explanation backwards. It’s fine to say that the computational role (e.g. global accessibility) of something necessitates its having a phenomenal character. But things don’t go the other way: p.c.’s don’t necessitate things having certain computational roles. And even if they did, that wouldn’t explain why you couldn’t give thought the relevant c.r. and skip the inner speech.

38. Linguistic Encoding There’s also the question as to how something linguistically encoded (like inner speech) could in principle be globally accessible. Just how many mental faculties can process language?

39. Computational Explanation I’m going to argue for the third possibility. Inner speech does have a purpose (contra possibility #1), but that purpose doesn’t lie in the fact that it’s conscious (contra #2). Instead, inner speech has computational properties that make it of use; its consciousness is a side-effect of its status as a perception, not what’s worthwhile about it. The consciousness of inner speech is a red herring.

40. 4. The computational explanation

41. Adding Numbers Suppose I ask you, out loud, to add “five million, four hundred and three thousand, nine hundred and ninety four and four hundred and forty six thousand, eight hundred and thirteen.” Probably, you can’t do it. Maybe you can, if you were quick enough to write down the numbers as I was saying them. And then when you solved the problem you’d use paper and pencil as well.

42. Why Not Native? But why don’t you use your native number representations and your native addition algorithm to solve the problem? Why not take your concept of 5,403,994 (which was activated when you understood me saying “five million, four hundred and three thousand…”) and your concept of 446,813, and then add them together using LOT’s addition algorithm?

43. Possibilities • Maybe LOT can’t add. You can think 5, and you can think 2, and you can think 5 + 2, but there’s no program in LOT that will take you from there to 7. • Maybe LOT can’t add large numbers. Maybe its addition algorithm is a lookup table that doesn’t handle arguments higher than 8.

44. More Possibilities • Maybe there is a native algorithm for addition, but it’s inefficient for large inputs. • Maybe we can add natively, but we can’t convert the sums back into English. • Maybe we are like chimps and gorillas and don’t even have the concept of 446,813. You can’t compute functions over representations you don’t have.

45. Benefits of Paper

46. Benefits of Paper Even if you have no native concept of numbers, or no means of natively computing sums with such concepts, you can still write down Arabic numerals and compute sums with them (provided you can recognize shapes and you remember what shapes to write down when you see which other shapes, etc. You can be a Chinese… er… Arabic Number Room, even as an innumerate.

47. Visualization And when we don’t have paper, we can resort to the next best thing: mental paper. We can imagine the symbols written out– re-create our perceptions of the written symbols– and manipulate them in imagination.

48. Arabic numerals provide an advantageous representational format for solving arithmetic problems. The suggestion then is that linguistic expressions provide an advantageous representational format for solving epistemic problems (what should I believe, given my evidence?).

49. The way I’m imagining this happening is this. Suppose for whatever reason our native machinery can’t work out some instance of, say, disjunctive syllogism. Let’s say that it’s just incapable of inferring the right disjunct from a disjunction and the negation of its left disjunct.

50. We have the ability to translate these LOT premises (conditional and antecedent) into English. So suppose we do that and get: “P or Q” “not-P”