Right hemisphere language ability: 1. Clinical evidence

The balance model of dyslexia and remedial training: an evaluative study

The aim of this study was to test the validity of Bakker's (1983, 1990) theory and treatment paradigm of dyslexia. Twenty-one children (mean age = 9.9 years) categorized as P-type dyslexics (showing accurate but slow and fragmented reading) and 19 children (mean age = 9.7 years) categorized as L-type dyslexics (fast but inaccurate readers) were presented with hemisphere-specific stimulation (HSS) and hemisphere-alluding stimulation (HAS). HSS was produced by presenting words to either the left or the right visual half-field, or to the left or right hand of the participant. HAS training was achieved through the presentation of either semantically/phonetically demanding or perceptually demanding text. Participants were given either a treatment program that was specifically designed for their particular dyslexia subtype, or a program that had been deliberately chosen to be inconsistent with their subtype. Contrary to predictions, participants made gains on all of the reading measures, regardless of the type of treatment given. On the basis of these findings it is suggested that treatment gains made are due to nonspecific training effects and not to the specific nature of Bakker's remedial strategies.

Word fluency after a right-hemisphere lesion

Joanette and Goulet (Neuropsychologia, 1986, 24, 875-879) reported that right-handed patients suffering from a right-hemisphere stroke were impaired on semantic but not on orthographic criteria when they were submitted to a word fluency task. The interpretation of this dissociation was that the right hemisphere would subtend a particular contribution to the semantic component of word processing in right handers. The goal of the research reported here was to challenge this dissociation. In contrast with the first study, the production criteria were presented randomly and their level of productivity was a controlled factor. The semantic-orthographic dissociation was not replicated under these conditions.