Double trouble: Using spellings of different lengths to represent vowel length in English.

Much previous research on spelling and reading development has focused on single-syllable words. Here we examined disyllables, asking how learners of English mark the distinction between short and long first-syllable vowels by use of vowel digraphs and double-consonant digraphs. In a behavioral study, we asked participants in Grade 2 (n = 32, mean age ∼8 years), Grade 4 (n = 33, mean age ∼10 years), Grade 6 (n = 32, mean age ∼12 years), and university (n = 32; mean age ∼20 years) to spell nonwords with short and long first-syllable vowels. We found an increase across grade levels in use of vowel digraphs to represent long vowels, and we also found increasing use of double-consonant digraphs after short vowels. Participants generally avoided using both a vowel digraph and a following consonant digraph. In a vocabulary analysis, we examined use of vowel and double-consonant digraphs in the words to which readers of different grade levels are exposed. Children used vowel digraphs less often than anticipated on the basis of the vocabulary statistics, but university students used them at similar rates. For double-consonant digraphs after short vowels, rates of digraph use were lower in the behavioral data than in the vocabulary data even for university students. These results point to the difficulty of spelling a phoneme with multiple letters when those letters simultaneously spell another sound in a word. We discuss the results in terms of the roles of statistical learning and explicit instruction in the development of spelling.