Why Inner Speech?

1. Why Inner Speech? Michael Johnson VAP Lingnan University (HK)

2. Outline • What Is Inner Speech? • Why Inner Speech? • Inner Speech and Attention • Conclusion

3. 1. What is inner speech?

4. Inner Speech As I’ll use the term, “inner speech” is a label for the phenomenon we naturally describe as “thinking in English/ Cantonese/ Catalan/ Kalaallisut/ etc.” But what is the nature of this phenomenon and how is it related to thought and “outer” speech?

5. 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.

6. Arguments that LOT ≠ English Greater indeterminacy of English compared with LOT: • Lexical ambiguity: “Fred went to the bank.” • Structural ambiguity: “Flying planes can be dangerous.” • Scopal ambiguity: “Every boy loves some girl.”

7. Processes Implicated in Speech • Lexical selection: selecting lexical items • Syntactic encoding: arranging the lexemes according to the syntactic rules • Phonological code retrieval [encoding]: retrieving [producing] phonological information • Phonetic encoding: Putting the information into an articulatory code • Articulation

8. Lexical Selection: Left Middle Temporal Gyrus, Mid Section

9. Syntactic Encoding: Left Inferior Frontal Gyrus/ Broca’s Area

10. Syntactic Encoding: Middle Frontal Gyri

11. Syntactic Encoding: Superior Parietal Lobule

12. Phonological Code Retrieval: Right Supplementary Motor Area

13. Phonological Code Retrieval: Left Anterior Insula

14. Phonological Code Retrieval: Wernicke’s Area

15. Phonological Encoding: Broca’s Area

16. Phonological Encoding: Left Mid-Superior Temporal Gyrus

17. 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 phonetic encoding and articulation.

18. Broca’s Area Finally, patients with damage to Broca’s area can suffer expressive aphasia– an inability to speak or write words. Transcranialmagnetic stimulation of Broca’s area has been shown to inhibit inner speech (Aziz-Zadeh, Cattaneo, Rochat & Rizzolatti, 2005)

19. The Phenomenal Character of IS Inner speech is an auditory phenomenon. • The phrase “hear myself think” gets 1.4m google hits compared with 640,000 for “feel myself think.” • Interestingly, BA 41/42 (the auditory cortex) is not (to my knowledge) activated in inner speech. The auditory cortex contains the neural correlates of auditory consciousness.

20. Summary • Inner speech is distinct from thought. • Inner speech involves all of the brain areas used in encoding thought into language except the areas involved in phonetic encoding and articulation. • Inner speech is an auditory phenomenon(?)

21. General Model Thought ↓ Linguistic encoding (LE) of thought ↓ LE sent to speech production apparatus = outer speech

22. General Model Thought ↓ Linguistic encoding (LE) of thought ↓ LE sent to auditory mechanism = inner speech

24. 2. Why inner speech?

25. “What good could talking to yourself do, if you already knew what you intended to say?” Dennett (1991 p. 301)

26. The Basic Puzzle Suppose I have a thought. If I don’t plan on communicating it to anyone in the foreseeable future, why would I: • Find the words that express the components of the thought; • Arrange them according to the rules of grammar; • Figure out how they would sound; • And then “listen” to them?

27. Some Solutions I Don’t Like • There’s no reason why we engage in inner speech. Only a befuddled hyper-adaptationist would think there had to be a reason. • The reason has nothing to do with inner speech: inner speech is a side-effect. • Inner speech is conscious whereas our “unspoken” thoughts aren’t: inner speech allows us to “globally broadcast” information.

28. No Function? The burden of proof is always on the side that wants to claim that a cognitive feature is adaptive and does have a function. That being said, there’s plenty of evidence that deficits in inner speech (either temporary or permanent) result in severe cognitive impairment.

29. Benefits of Inner Speech Here are just some of the areas impaired by a deficit in inner speech: • self-awareness • intelligence • mathematical ability • memory

30. Side-Effect Story For fully verbalized outer speech, it is necessary to encode our thoughts in language, and to do so very rapidly. Ideally, we would perform this encoding only when necessary, but nature is rarely ideal. Instead we perform the encoding even in those large number of instances where we have no plans to engage in verbal behavior.

31. Problems for Side-Effect Story • The story doesn’t explain how inner speech conveys the benefits to intelligence, memory, etc. • There’s an extra step in inner speech that’s not needed in “outer” speech: routing the phonological representations to the auditory cortex.

32. “Global Broadcast” Story Carruthers suggests that inner speech exists as a medium for the different modules to “talk to” one another. This seems implausible. How could something linguistically encoded in principle be globally accessible? Just how many mental faculties can process language?

33. Here’s the Story I Like A salient difference between thought and audition is that the former is essentially non-perceptual and the latter is essentially perceptual. As we’ll see, that makes quite a difference.

34. 3. Inner speech and Attention

35. In the rest of the talk, I want to try to outline how it is that inner speech is involved in what research says it’s involved in: • Memory • Mathematical Ability • Self-Awareness • Intelligence

36. Attention Attention involves selecting an aspect of our perceptions (or our sensations) and allocating additional cognitive resources to that aspect. Attention can thus only be provided to and withheld from perceptions and sensations.

37. Short-Term Memory Knudsen (2007) sees attention as the means by which information enters short-term memory. Thus for information to enter short-term memory, it must come to us through sensation or perception.

38. Inner Speech and Memory Inner speech, as I’ve argued, is an auditory phenomenon. Thus it, unlike ordinary thought*, is precisely the sort of thing we can attend to. Unsurprisingly, research has shown that inner speech aids in memory (Baddely 1986).

39. Memory • Mathematical Ability • Self-Awareness • Intelligence

40. Memory and Mathematics Performing all but the simplest arithmetical calculations requires storing the values of intermediate calculations in short term memory. If attention is essentially perceptual, and is also the gateway to short-term memory, then a perceptual presentation of arithmetical problems is necessary for solving them.

41. Inner Speech and Arithmetic This presentation can be visual (on a chalkboard, for example), but it can also be auditory. Research reveals that private speech increases arithmetical ability in children (Ostad & Sorensen 2007) and that one of the cognitive deficits that faces deaf individuals who have learned no language is poor arithmetical ability.

42. Memory • Mathematical Ability • Self-Awareness • Intelligence

43. Self-Awareness Self-awareness is “the capacity to become the object of one’s own attention (Duval and Wicklund, 1972), where the individual actively identifies, processes, and stores information about the self… Self-awareness involves attention paid to one’s own mental states (such as perceptions, sensations, attitudes, intentions, emotions, etc.) and public self-characteristics.” [Morin 2005, emphasis mine]

44. Self-Awareness and Inner Speech “[T]hrougha process of labeling, categorizing, and engaging in language-based modes of representation, a person not only represents internal states and experiences (sentience) but acquires the capacity to reflect on them. [Burns & Engdahl 1998: 179] “Without language [internal monitoring remains] relatively primitive, vague, unelaborated.” [171]

45. Self-Awareness and Inner Speech Here’s the basic picture: Awareness of our own thoughts is difficult to come by. The best way to get it is to translate the thought into language, then “speak” it to ourselves. This allows us to attend to the thought and discover what we are thinking.

46. Memory • Mathematical Ability • Self-Awareness • Intelligence

47. Why We Are So Clever “[A] creature that knows what would make its thoughts true and what would cause it to have them, would be in a highly advantageous epistemic position:…”

48. Why We Are So Clever “It would be able, with premeditation, to cause itself to have true thoughts. In particular, to construct, with malice aforethought, situations in which it will be caused to have the thought that P if and only if the thought that P is true.”

49. Why We Are So Clever “I think it's likely that we are the only creatures that can think about the contents of our thoughts.”

50. Memory • Mathematical Ability • Self-Awareness • Intelligence