I have two problems with the statement that "stuttering is largely psychological" Problem 1: I don't know what the person saying this mean by "stuttering." Do you mean the condition of stuttering? Or the moments of stuttering? Problem 2: I don't know what the person saying this means by "psychological." Are you painting with broad strokes and refer to anything related to cognition as psychological? Or are you referring to a narrower definition of psychology relating to one's self perception? Or are we talking about how the field of psychology in the broadest of senses as the study of human behavior and function? I could agree with the statement that "stuttering is psychological" if we set up some intellectual constraints. But without knowing exactly what you're saying I don't really agree nor disagree. The experience of stuttering can create psychological complications, however, whether the root of stuttering is "psychological" (however defined) requires a much more nuanced debate. Also there's something about a psychologist saying stuttering is psychological in nature that doesn't quite pass the "sniff test" (e.g., the more "psychological" issues a patient has, treatment becomes protracted, the psychologist makes more money ... this is a bit of a pessimistic view, and I don't think that psychologists are generally out to make money with nefarious predatory intent. But make sure the snake isn't eating its tail).