A frustrating aspect of the study was that we don't know how common dyslexia is in musicians. The authors mention that Nigel Kennedy and John Lennon were dyslexic, but the evidence is anecdotal and there appear to have been no proper surveys to compare the prevalence of dyslexia in musicians with other types of expert.
Be this as it may, Weiss et al managed to recruit a group of 24 professional musicians who reported difficulty reading, who were compared with other musicians matched for age, musical education and reasoning skills. They screened these individuals to confirm that the dyslexic group were poor on reading measures, whereas the control group was not. The study did also include parallel groups of dyslexics and controls who were not musicians, but these were recruited from a different study and they did not complete all of the same experimental measures.
|Musicians with dyslexia were impaired on measures of auditory working memory|
So can we conclude from this study that problems in basic auditory perception are not implicated in dyslexia? Well, things are not so simple. Few people would accept that all dyslexia is the same: it is likely that there are multiple reasons for reading failure. So showing that someone is dyslexic despite good auditory perception is not all that informative: their dyslexia might arise from another cause. It would be more interesting if one could show that someone was not dyslexic despite poor auditory perception. In fact, there are such instances in the literature: Ayotte et al (2002), for instance, described eleven individuals with congenital amusia, who reported no learning difficulties except with music. And our group have studied children with mild-moderate hearing loss who had age-appropriate literacy scores despite poor auditory discrimination. So there are reasons to question whether the auditory deficit observed in many (non-musician) dyslexics is a causal factor. It therefore is interesting to ask whether the dyslexic musician data might suggest alternative approaches.
Given that auditory perceptual problems were not at the root of the dyslexia in musicians, then what is? The authors proposed that deficient auditory memory was the culprit. The dyslexic musicians seemed to have a generic problem with short-term retention of all kinds of auditory material, be it verbal or nonverbal. This suggests one of two possible interpretations: first, there could be two kinds of dyslexia: one (seen in non-musicians) due to impaired auditory discrimination, and the other (seen in musicians) to poor auditory memory. Alternatively, the notion of an auditory discrimination deficit could be a red herring, with auditory memory a more salient reason for poor reading in all people, both musicians and non-musicians. It is unfortunate that data on the nonverbal auditory memory tasks was not available for the non-musicians, as this might have helped distinguish these possibilities.
Nevertheless, there are reasons to be cautious in interpretation of these results. The memory limitations found in the dyslexic musicians were surprising, because one might have anticipated that such a deficit would be a handicap for a professional musician. One question that this study raises is whether the specific auditory tasks used in this study might have elicited specific strategies in those with musical training which could confound interpretation of them as pure memory measures. There may have been benefit in mentally encoding the materials in memory tasks by verbal labels or visualising a musical score. It is possible that the dyslexic vs non-dyslexic musicians differed in the ease with which they adopted such strategies, and that this, rather than any more fundamental memory deficit, led to group differences.
Altogether this is an intriguing study that is far from conclusive but does raise further questions about the relationship between verbal and nonverbal auditory processing, as well as suggesting that auditory memory may be a more crucial component of dyslexia than basic auditory discrimination. And it opens a new line of research into dyslexia in musicians, who are a fascinating group because of their prolonged training in aspects of auditory perception.
Weiss, A., Granot, R., & Ahissar, M. (2014). The enigma of dyslexic musicians Neuropsychologia, 54, 28-40 DOI: 10.1016/j.neuropsychologia.2013.12.009
Post written for the BPS Research Digest by guest host Dorothy Bishop, Professor of Developmental Neuropsychology and a Wellcome Principal Research Fellow at the Department of Experimental Psychology in Oxford, Adjunct Professor at The University of Western Australia, Perth, and a runner up in the 2012 UK Science Blogging Prize for BishopBlog.