A previous explanation of the sex difference on so-called perceptual speed tests was in terms of a female advantage in accessing and using phonological name codes in making item comparisons. That explanation was extended to a task involving alphabetical transformations without the requirement for comparison of perceptually available items. A single transformation problem required incrementing a letter of the alphabet by 1, 2, 3, or 4 letters, e.g. D + 4, where the correct response is H. A double transformation problem required two transformations, DL + 4. In two experiments the size of the sex difference was related to the length of the increment. The greatest sex differences in both experiments were found for the longest increment on the double transformation condition with size-of-effect values (d) of 0.80 and 0.87. This increase in the size of the sex difference with increased demands on the use of phonological name codes was interpreted in terms of a sex difference in speech-based processing.