Word recognition under spatial transformation in retarded and normal readers.

The recognition of words in normal, reversed, and inverted orientation was compared in a group of 9- to 11-year-old retarded readers and a matched group of normal readers. Using the ratio of reading times as an index of reading difficulty under spatial transformation, the results confirmed those of earlier studies which have shown that retarded readers' performance is less affected by spatial transformation than is normal readers'. However, an analysis in terms of the ratio of numbers of words read correctly pointed to just the opposite conclusion. The two sets of findings were reconciled by showing that they follow from the form of the function relating reading time to number correct, and by demonstrating that when word lists are equated for orthographic familiarity the performances of retarded and normal readers are equally affected by spatial transformation, whether the time or number ratio is used as an index.