The Little Voice in Your Head: Error-based Investigations of Abstracted and Articulated Inner Speech by Gary

Inner speech, that little voice that people often hear inside their heads while thinking, is a form of mental imagery. The properties of inner speech errors can be used to investigate the nature of inner speech, just as overt slips are informative about overt speech production. Overt slips tend to create words (lexical bias) and involve similar exchanging phonemes (phonemic similarity effect), two speech-error phenomena that have been localized to an articulatory-feature processing level and a lexical-phonological level, respectively. In the first chapter, we examine these effects in inner and overt speech via a tongue-twister recitation task. While lexical bias was present in both inner and overt speech errors, the phonemic similarity effect was evident only for overt errors, producing a significant overtness by similarity interaction. We propose that inner speech is impoverished at lower (featural) levels, but robust at higher (phonemic) levels. In the second chapter, we focus on the role of articulation and motor imagery in inner speech, comparing inner speech without articulatory movements to articulated (mouthed) inner speech. As before, the speech errors occurring during unarticulated inner speech did not exhibit the phonemic similarity effect—just the lexical bias effect. In contrast, speech errors that occurred in articulated inner speech exhibited the phonemic similarity effect and lexical bias effect, similar to our previous findings for overt speech. The results constrain our previous interpretation and are interpreted as support for a flexible abstractness account of inner speech. That is, articulatory information is incorporated into inner speech if it is available, but is not essential to the phenomenon. This conclusion has ramifications for issues related to the embodiment of language and speech and for the theories of the processes involved in speech production.