Motor movement matters : The flexible abstractness of inner speech

nothing more than inner speech, a weakened form of overt speech in which movements of the articulators occur but are too small to produce sound (Watson, 1913). A remarkable experiment by S. M. Smith, Brown, Toman, and Goodman (1947) demonstrated that this idea was false. Abolishing any trace of articulation through curare-induced total paralysis (requiring a respirator!) did not impair the participant’s (Smith, himself) ability to think or understand his colleagues’ speech. So Watson’s bold claim (i.e., thought 5 inner speech 5 articulation) could not be true. Nevertheless, there remains a great deal of interest in inner speech and the role of motoric processes in language and cognition. In this article, we report an experiment that (without curare) elucidates the relationship between articulation and inner speech imagery. Many recent studies have investigated the extent to which linguistic representations have sensory or motoric components—the central question of the embodiedcognition framework. Embodiment, in the domain of language processing, is usually taken to be about whether meaning is sensory–motor in nature—specifically, in terms of engaging sensory or motor simulations of the events signified by linguistic referents (e.g., Barsalou, 1999; Lakoff, 1987; Pulvermüller, 2005). For instance, understanding the word reach may require basic visual, auditory, proprioceptive, and motoric circuitry to simulate the act of reaching so that the main difference between actually reaching and merely understanding the word reach is an apparent lack of motor movement. But a second question arises concerning embodiment and language: Speech, regardless of its meaning, is the result of motor action. Given this, do internal representations of speech have motor components? The motor theory of speech perception (Galantucci, Fowler, & Turvey, 2006; Liberman, Delattre, & Cooper, 1952; Liberman & Mattingly, 1985) is a classic example of a theoretical stand on this question. It claims that listeners interpret an acoustic speech signal as the result of specific articulatory movements, covertly simulating the movements as a step toward recognizing the semantic conditions that created them. Thus, covert articulatory simulations are posited to play a central role in the mapping from sound to meaning. A second example, and the one that we investigate here, concerns the nature of inner speech—the silent, internal speech that Watson (1913) referred to. Although we know that inner speech is not the basis of thought, it does accompany and clearly supports many cognitive activities, such as planning, reading, and memorization (e.g., Sokolov, 1972; Vygotskiı̆, 1965; see also, e.g., J. D. Smith, Reisberg, & Wilson, 1992, for how auditory verbal imagery contrasts with inner speech). Inner speech is generally thought of as the product of a truncated overt speech production process. Theories differ, however, about where this truncation lies (see Figure 1). Of particular interest is the distinction between a phonological level of processing (with units called phonemes or phonological segments) and an articulatory level (with units called articulatory or phonetic features). Phonemes, in the speech production process, are sometimes consid-