Are judgments of the positional frequencies of letters systematically biased due to availability?

How do people estimate whether a particular letter is more frequent in the Ist versus in a later position? The authors tested 2 precise versions of the availability hypothesis, a hypothesis that assumes that frequency processing occurs on the level of the phonological classes of vowels and consonants, and the regressed-frequencies hypothesis, which assumes monitoring of individual letters. Across 3 studies, it was found that (a) judgments of whether a letter is more frequent in the Ist or the 2nd position generally followed the actual proportions and (b) the estimated relative frequencies in the Ist versus the 2nd position closely agreed with the actual rank ordering, except for an overestimation of low and underestimation of high values. These results favor the regressed-frequencies hypothesis and challenge the conclusions about frequency judgments in the heuristics and biases literature.