ABSTRACT
This chapter reviews three theories that explain stuttering primarily, although not solely, in terms of cognitive processing.
THE NEUROPSYCHOLINGUISTIC THEORY
According to the neuropsycholinguistic (NPL) theory, stuttering is caused when sounds are not inserted in a timely fashion into syllables during speech production (Perkins, Kent, & Curlee, 1991). Stuttering occurs when articulatory rate “exceeds the rate at which segments can be integrated synchronously into their syllable frames” (p. 748). This condition is attributed to dyssynchrony of the two neural systems that are responsible for this insertion process, namely the symbol system and the signal system. The symbol system is concerned with linguistic processing, while the signal system is responsible for providing syllable frames. For the dyssynchrony between the two systems to cause stuttering it must be due to a delay in the arrival of the syllable frames, which contain the slots into which speech segments are to be inserted. Thus, only one type of dyssynchrony is a necessary condition for stuttering to occur.
