Success Is Not the Entire Story for a Scientific Theory: The Case of the Phonological Deficit Theory of Dyslexia

In a recent paper, Share discussed four different Common Misconceptions about the Phonological Deficit Theory of Dyslexia and described this theory as a model of true scientific progress and a clear success story. In this note, I argue that at least part of the success of this theory is due to the lack of explicit predictions which make it very difficult (if possible) to test its predictions, and, possibly, falsify the theory. Some areas of pertinent research, including categorical phoneme perception, picture naming, and phonological awareness are summarized. Furthermore, two lines of research in which groups of researchers have attempted to formulate more explicit predictions are briefly outlined. It is concluded that, although much research has variously referred to the phonological deficit theory of dyslexia, the resulting large body of evidence presents a complex pattern of results which, in the absence of an explicit formulation of the theory, is extremely difficult to frame within a unitary interpretation. Overall, what seems needed is a theoretical formulation that, on the one hand, can account for the complex pattern of available evidence and, on the other hand, provide testable predictions for future research.

Automated summary

In this article, the author discusses common misconceptions about the Phonological Deficit Theory of Dyslexia and argues that part of its success is due to the lack of explicit predictions. The author summarizes relevant research areas and outlines two lines of research attempting to formulate more explicit predictions. It is concluded that a theoretical formulation is needed that can account for the complex pattern of evidence and provide testable predictions for future research.