When orthography is not enough: The effect of lexical stress in lexical decision

Three experiments investigated the impact of five lexical variables (instance dominance, category dominance, word frequency, word length in letters, and word length in syllables) on performance in three different tasks involving word recognition: category verification, lexical decision, and pronunciation. Although the same set of words was used in each task, the relationship of the lexical variables to reaction time varied significantly with the task within which the words were embedded. In particular, the effect of word frequency was minimal in the category verification task, whereas it was significantly larger in the pronunciation task and significantly larger yet in the lexical decision task. It is argued that decision processes having little to do with lexical access accentuate the word-frequency effect in the lexical decision task and that results from this task have questionable value in testing the assumption that word frequency orders the lexicon, thereby affecting time to access the mental lexicon. A simple two-stage model is outlined to account for the role of word frequency and other variables in lexical decision. The model is applied to the results of the reported experiments and some of the most important findings in other studies of lexical decision and pronunciation.

The links between spellings and sounds in a large set of English words with consonant-vowel-consonant phonological structure were examined. orthographic rimes, or units consisting of a vowel grapheme and a final consonant grapheme, had more stable pronunciations than either individual vowels or initial consonant-plus-vowel units. In 2 large-scale studies of word pronunciation, the consistency of pronunciation of the orthographic rime accounted for variance in latencies and errors beyond that contributed by the consistency of pronunciation of the individual graphemes and by other factors. In 3 experiments, as well, children and adults made more errors on words with less consistently pronounced orthographic rimes than on words with more consistently pronounced orthographic rimes. Relations between spellings and sounds in the simple monomorphemic words of English are more predictable when the level of onsets and rimes is taken into account than when only graphemes and phonemes are considered.