Abstract
Much of the confusion which has arisen as to the nature of dyslexia is because retarded human readers were so frequently studied as if they formed a qualitatively homogeneous group. Reading is probably not a unitary process. It involves the acquisition of a succession of skills and different retarded readers may break down at different stages in the acquisition of these. There may be types of retarded readers who are unable to analyze complex visual shapes, to analyze whole word sounds into phonemes, to make simple regular grapheme-phoneme associations, to grasp irregularities in these or to group single words into phrases and sentences. Each of these disabilities may be associated with a particular type of deficiency in conceptual thinking.