Effects of grammatical categories on letter detection in continuous text.

The present study focuses on the interplay between the linguistic principles and the psycholinguistic processes involved in reading. Results from 56 participants on a letter detection task reveal that readers do not process all function words in the same manner. Omission rates were highest for function words occupying the head of maximal projections such as complementizers and determiners. Prepositions were shown to occupy an intermediary position between content and function words, with omission rates varying depending on their semantic load. Together these results appear to bolster and offer a finer grained picture of the role of function words within the framework of both the Guidance Organization (Greenberg et al. in Psychon Bull Rev 11(3):428-433, 2004) and Attentional Disengagement (Roy-Charland et al. in Percept Psychophys 69(3):324-337, 2007) reading models. The results of the present study are discussed using an X-bar theory approach with the goal of refining the structural account of letter detection errors.