Quick summary of our in class discussion of "The Motor Theory of Speech Perception Reviewed" by Galantucci et al. (2006), Psychonomic Bull. & Rev., 13: 361-77.
1. Very worthwhile and thorough article. Everyone needs to read it.
2. The authors make an excellent case for the fact that there is a very tight connection between speech perception and speech production.
3. In contrast to the authors' conclusions however, none of the arguments make a case for the central claim of the Motor Theory, that "Perceiving speech is perceiving phonetic gestures." p. 367. Instead, I would argue that there is much better evidence for the reverse claim: That speech production is producing auditory targets. Call it the Perceptual Theory of Speech Production. (See Frank Guenther's work for computational implementations of this viewpoint.) This view has all the advantages of the Motor Theory in terms of maintaining parity between perception and production, and explaining the tight association between sensory and motor systems, AND, unlike the Motor Theory is consistent with the empirical facts from aphasia, namely that damage to frontal speech production systems does not lead to a concomitant impairment in speech recognition, whereas damage to posterior auditory-related brain regions does produce production deficits.
4. Relatedly, and as pointed out in a previous post, evidence from aphasia is glaringly lacking from the otherwise very thorough review.
I would love to have a discussion about #3, in particular, whether anyone can think of any evidence to support a Motor Theory account rather than a Sensory Theory account. I didn't see it in the Galantucci et al. paper, which is the best review I've seen, so speak up if you disagree! I would love to know why I'm wrong.