Letter detection errors in reading, auditory, and memory tasks

Abstract

Previous work with the letter detection task has revealed that subjects miss the letter t in the word the more often than in other words. This effect has been attributed to unitization of common words. To test for unitization, three experiments were conducted using three new versions of the letter detection task: detection from a memorized text, from an auditorily presented text, and from reading a text. The findings of unitization were replicated in the reading task but no evidence for unitization was found in the auditory task. A post hoc analysis of subjects' retrospective reports of how they searched for the letters in memory indicated that those who reported a visual search method had more errors on the compared to other words, whereas those who reported an auditory method did not. All of these results support the hypothesis that the unitization effect occurs only when reading, either from a visual representation in memory or from a visual display.