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Purpose: We advanced a multifactorial, dynamic account of the complex, nonlinear interactions of motor, linguistic, and emotional factors contributing to the development of stuttering. Our purpose here is to update our account as the multifactorial dynamic pathways theory.
Method: We review evidence related to how stuttering develops, including genetic/epigenetic factors; motor, linguistic, and emotional features; and advances in neuroimaging studies. We update evidence for our earlier claim: Although stuttering ultimately reflects impairment in speech sensorimotor processes, its course over the life span is strongly conditioned by linguistic and emotional factors.
Results: Our current account places primary emphasis on the dynamic developmental context in which stuttering emerges and follows its course during the preschool years. Rapid changes in many neurobehavioral systems are ongoing, and critical interactions among these systems likely play a major role in determining persistence of or recovery from stuttering.
Conclusion: Stuttering, or childhood onset fluency disorder (Diagnostic and Statistical Manual of Mental Disorders, 5th edition; American Psychiatric Association [APA], 2013), is a neurodevelopmental disorder that begins when neural networks supporting speech, language, and emotional functions are rapidly developing. The multifactorial dynamic pathways theory motivates experimental and clinical work to determine the specific factors that contribute to each child's pathway to the diagnosis of stuttering and those most likely to promote recovery.
We have advanced a multifactorial, dynamic account of the complex, nonlinear interactions of motor, linguistic, and emotional factors that contribute to the onset and development of stuttering (Smith, 1990, 1999; Smith & Kelly, 1997). Most researchers investigating stuttering now agree that stuttering cannot be explained by a single-factor theory although current accounts provide primary emphasis on varying factors, for example, the dual diathesis-stressor model of Walden et al. (2012). Our original perspective emphasized ongoing interactions among speech motor, linguistic, and emotional processes and drew from dynamic systems theory (e.g., Bassingthwaighte, Liebovitch, & West, 1994; Glass & Mackey, 1988) to better understand the idea of causality in the development of complex human behaviors such as stuttering. We offered what we believed to be a more integrated approach to understanding stuttering because the literature on stuttering in the 1990s was "fragmented and confusing" (Smith, 1999, p. 27). It was common practice for experimental and clinical papers on stuttering to be written on the...