Extra-large letter spacing improves reading in dyslexia

Abstract

Although the causes of dyslexia are still debated, all researchers agree that the main challenge is to find ways that allow a child with dyslexia to read more words in less time, because reading more is undisputedly the most efficient intervention for dyslexia. Sophisticated training programs exist, but they typically target the component skills of reading, such as phonological awareness. After the component skills have improved, the main challenge remains (that is, reading deficits must be treated by reading more--a vicious circle for a dyslexic child). Here, we show that a simple manipulation of letter spacing substantially improved text reading performance on the fly (without any training) in a large, unselected sample of Italian and French dyslexic children. Extra-large letter spacing helps reading, because dyslexics are abnormally affected by crowding, a perceptual phenomenon with detrimental effects on letter recognition that is modulated by the spacing between letters. Extra-large letter spacing may help to break the vicious circle by rendering the reading material more easily accessible.

Fig. 1.

Samples of the text read by the dyslexic and normally developing children matched for reading level. (A) Normal text. (B) Spaced text.

Fig. 2.

(A) Reading accuracy measured in terms of number of errors (incorrect words) as a function of group and testing time. Group 1 read normal text at the first time of testing (T1) and spaced text at the second time (T2), whereas group 2 had the opposite assignment. (B) Reading speed, in syllables per second, as a function of group and testing time. (C) Reading accuracy (number of errors) in the normal and spaced text conditions for Italian dyslexics, French dyslexics, and a younger group of Italian control children matched for reading level (RL) to the Italian dyslexic sample. (D). Reading accuracy (number of errors) for a subsample of dyslexic children that was tested a third time. Group 1 read normal text at T1, spaced text at T2, and normal text at T3, whereas group 2 had the opposite assignment. Error bars show SEM.

Fig. 3.

Experiment 2. (A) Reading accuracy measured in terms of number of errors (incorrect words) and (B) reading speed, measured in syllables per second, as a function of spacing condition and testing session. Two matched texts were administered in each testing session. The two texts in session 1 had the same (wide) line spacing, whereas in session 2, the normal text had normal line spacing (as in experiment 1). The assignment of each text to the spacing condition in session 2 was reversed with respect to session 1. Error bars show SEM.