Is the Missing Letter Effect Due Primarily to Lexical Factors or to the Global Semantic Context?

Abstract A letter detection task, in which readers mark target letters in prose passages, has revealed the missing letter effect, in which letter detection accuracy is especially low on frequent function words. Healy et al. (2023) explored whether the missing letter effect is due to lexical factors or to semantic factors. In a passage including unrelated sentences that were either intact or randomly rearranged, test words differed in word frequency but were surrounded by the exact same words in each passage type. There was an effect of word frequency on letter detection accuracy but no effect of passage type, thereby implicating lexical factors in the missing letter effect. In the present study, function words varying in word frequency occurred in two prose passages, with some test words in each passage correctly spelled and others misspelled. Global semantic context was also manipulated by providing the passage theme either before or after reading the passage. Both word frequency and word spelling affected the magnitude of the missing letter effect. The location of the passage theme did not affect letter detection errors, although it did affect comprehension ratings. The results provide further evidence for the influence of lexical factors, but not of global semantic context, on the missing letter effect.