Proofreading Errors on the Word The: New Evidence on Reading Units

This experiment is based on the following paper:

Healy, A. (1980). Proofreading Errors on the Word The: New Evidence on Reading Units. Journal of Experimental Psychology: Human Perception & Performance, 6, 45-57. Copyright (1980) by American Psychological Association.


Words can be processed at several different levels. They can read as a phrase, a word, or letter-by-letter, depending upon the task demands placed on the reader. In letter-detection tasks, where subjects are supposed to identify all instances of a particular letter in a prose passage, they are particularly likely to make errors on the word the Healy proposed a unitization hypothesis to account for the prevalence of this mistake. Completion of processing at a higher level is thought to halt processing at lower levels, so if word-level processing is finished, there is no need to continue processing individual letters. Since the is the most common word in English, it is rapidly processed at the word level. For a letter detection task, this means that more errors are made on detection of individual t s in the because letter-level processing is rarely completed. However, accuracy could change with a different task.

The present experiment uses a proofreading task, in which subjects must detect misspelled words in a prose passage. These words are misspelled by transposing two adjacent letters; i.e., elbow becomes elobw. This change should disturb letter level processing very little, since no letters have been replaced, but should greatly disturb word-level processing since it forms a non-word. In a proofreading task, Healy’s model predicts a higher degree of accuracy between the and other words. Because the is a very short word, transpositions will cause greater differences between the original and misspelling. Therefore, detecting such errors on the should be relatively easy.


The full text describing the experiment is available here.

The experiments are available below. (24.5 KB) (36.5 KB)