Note: Solid lines indicate obligatory relationships (i.e., " A leads to B"). Dashed lines indicate optional relationships (i.e. " A may lead to B")

(Presumed) Etiology: Abnormality of motoric, psycholinguistic, or neural processes underlying normal speech production.

Recent theories include:

-Covert Repair Hypothesis (Kolk & Postma, 1997)

-Demands/Capacities (Starkweather, 1997)

-Multifactorial (Smith & Kelly, 1997)

-Neuropsycholinguistic(Perkins, Kent, & Curlee, 1991)