Morphological errors in acquired dyslexia: A case of mistaken identity

Morphological errors in oral reading have been used to support theories of lexical access in which root morphemes and affixes are independently represented in the orthographic lexicon. No support for such theories was found in this study, which examined the morphological errors made by two patients with different patterns of acquired dyslexia. Instead, it was shown that the probability of making a morphological error depended upon the absolute levels of imageability and word frequency of the affixed word and the relative levels of its root morpheme. These properties also affected the oral reading of words without affixes. It was concluded that so-called “morphological” errors reflect the properties of the reading system which influence lexical orthographic access for both affixed and unaffixed words and further reflect the functional level of the lexical pathways available to the patient.