Induced letter migrations between words and what they reveal about the orthographic-visual analyzer

When skilled readers read briefly-presented word pairs, they produce between-word errors, in which letters migrate between neighboring words (e.g., mild wind can be misread as wild mind). Such errors are also produced by individuals with attentional dyslexia, even without time limitation. In this study, we tested several aspects of skilled reading of word pairs in short exposure, such as migrations between vertically and horizontally presented pairs, error types, position preservation, position sensitivity, and the effect of morphology. We compared the results to findings from developmental attentional dyslexia. Whereas both populations make between-word migrations, they crucially differ in the type and distribution of errors. In developmental attentional dyslexia, omission of identical letters that appear in the same position in the two words is prevalent, but it was rare in skilled reading. Other errors such as intrusions and buffer migrations also happened only in dyslexia but not in skilled reading. The different error patterns may suggest that different mechanisms underlie the incorrect reading in short exposure and the reading impairment in attentional dyslexia. Furthermore, the abundance of between-word migrations and the absence of letter position errors within words support that notion of two separate functions, one for letter-to-word binding, the other for letter position encoding.