Fillers and Spaces in Text: Implications for the Relative Importance of Word Recognition and Physical Features of the Text during Reading

The role of spaces between words in text was studied in many experiments by filling the spaces with irrelevant symbols. This practice is based on the assumption that these fillers occlude spaces without disturbing word recognition appreciably. There is no empirical evidence to support this assumption. We performed a series of experiments to study the role of fillers and spaces in text. We found that texts in all conditions in which words were surrounded by fillers were read more slowly than normal texts, as long as the fillers shared common features with the letters of the text (digits, irrelevant Latin letters, and Greek letters). Reading was as slow when words were surrounded by fillers (1like2 8this6), as when fillers replaced spaces (1like2this6), showing that reading was disrupted by the presence of fillers, not by the absence of spaces. Reading eye movements were recorded with some of the subjects and text conditions. The placement of fillers and the presence or absence of spaces in the text had no effect on percentage regressions, or on where reading saccades landed within words. However, more saccades per line were made in conditions that contained fillers than either with normal or with unspaced text. Observed differences in eye movement patterns and reading speed can be accounted for by a global adjustment to only one eye movement parameter, viz saccade size, made on the basis of the global appearance of the text. No evidence was found that the presence of fillers or the absence of spaces required new strategies for programming individual saccades. This suggests that word recognition and global strategies are more significant in programming reading saccades than the local physical features of the text.