Types of Amorphia: Different Morphological Disorders in Reading and Their Different Sources

EasyChair Preprint 6493

Abstract

We propose a model for reading morphologically complex words, and describe case studies of individuals with selective deficits in different components of this model.

The model proposes that the orthographic input lexicon(OIL) and the phonological output lexicon(POL) store stems and the Stem-Affix-Registry(STARs) for each stem, indicating the idiosyncratic information about derivational affixes that can attach to the stem. The orthographic input buffer(OIB) performs a structure-based analysis on the basis of the list of existing affixes, and the phonological output buffer(POB) assembles the morphologically-complex words/nonwords from their stem and affixes. A morphological route converts whole written affixes to their phonological representation. So in morphologically-complex words, stems are read through the lexical route, and affixes are converted in the morphological route.

We identified several types of amorphia, attributable to different loci in the proposed model: 3 patients had a deficit in the OIB, resulting in affix errors, in words and nonwords, in reading aloud,lexical decision,comprehension. Naming and repetition of morphologically-complex words and nonwords were intact.

One participant had a semantic lexicon-POL disconnection. His reading was intact, his lexical retrieval was impaired.

5 participants had a POL deficit, some a stem deficit once they could access the stem, they could reach the STARs and produce the matching affixes. Others had a STAR deficit , producing stems with non-matching affixes. Their lexical-decision and comprehension of morphologically-complex words were intact.

2 patients had a POB deficit, resulting in morphological errors in reading&production but not in input tasks.

A double dissociation was found between grapheme-to-phoneme and morphological conversion:3 patients had a deficit in reading nonexisting stems but read affixes correctly, and 3 showed the opposite pattern.

Keyphrases: Dyslexia, aphasia, morphologically complex words, reading model

@booklet{EasyChair:6493,
  author    = {Naama Friedmann and Reut Stark and Aviah Gvion and Max Coltheart},
  title     = {Types of Amorphia: Different Morphological Disorders in Reading and Their Different Sources},
  howpublished = {EasyChair Preprint 6493},
  year      = {EasyChair, 2021}}