Eva Kimel, Atalia Hai Weiss, Hilla Jakoby, Luba Daikhin, Merav Ahissar
Short-term memory capacity and sensitivity to language statistics in dyslexia and among musicians
Neuropsychologia, Volume 149
Low short-term memory capacity in individuals with dyslexia and enhanced short-term memory capacity in musicians are well documented, yet their causes are disputed. In this paper we claim that the difficulty of individuals with dyslexia stems from an inefficient learning from multiple exposures (red curve in Figure 1), and that the benefit of musicians stems from super-efficient learning from multiple exposures (purple curve in Figure 1). Individuals with dyslexia do not benefit to the same extent from multiple encounters with stimuli, and then, when they are tested for short-term memory and frequent items are used in the test, they get especially low results (right hand side of Figure 1). For musicians it is the other way around. So, at least to a large extent, the deficit in dyslexia and the benefit of musicians is not of short-term memory, but of the utilization of long-term memory while performing short-term memory tasks. By contrast, the learning of a repeated sequence was similar for all groups, so it is not that every measure of short-term memory in dyslexia is reduced and every measure in musicians is enhanced, but the deficit/advantage is specific. It seems that the learning of a repeated sequence is based on a different mechanism than the benefit of long-term item frequency. To verify this dissociation, we recruited native English speakers. Indeed, their spans for high-frequency syllables in Hebrew, which do not have high frequency in English, were small due to a reduced exposure to these syllables, but, as expected, their benefit from sequence repetition was similar to that of the three Hebrew-speaking groups.