Given that all the reading research psychologists I know support some version of the parallel letter recognition model of reading, how is it that all the typographers I know say that we read by matching whole word shapes? It appears to be a grand misunderstanding. The paper by Bouma that is most frequently cited does not support a word shape model of reading. Bouma (1973) presented words and unpronounceable letter strings to subjects away from the fixation point and measured their ability to name the first and last letters. He found that:
A) Subjects are more successful at naming letters to the right of fixation than to the left of fixation. B) When distance to the right of the fixation point is controlled, subjects are better able to recognize the last letter of a word than the first letter of word. This data explains why it is that we tend to fixate just to the left of the middle of a word.
Bouwhuis & Bouma (1979) extended the Bouma (1973) paper by not only finding the probability of recognizing the first and last letters of a word, but also the middle letters. They used this data to develop a model of word recognition based on the probability of recognizing each of the letters within a word. They conclude that ‘word shape … might be satisfactorily described in terms of the letters in their positions.’ This model of word recognition clearly influenced the McClelland & Rumelhart neural network model discussed earlier which also used letters in their positions to probabilistically recognize words.
Word shape is no longer a viable model of word recognition. The bulk of scientific evidence says that we recognize a word’s component letters, then use that visual information to recognize a word. In addition to perceptual information, we also use contextual information to help recognize words during ordinary reading, but that has no bearing on the word shape versus parallel letter recognition debate. It is hopefully clear that the readability and legibility of a typeface should not be evaluated on its ability to generate a good bouma shape.