The role of root frequency and grammatical category of base words in reading derived nouns: a study with primary-school skilled and poor readers

Recent reading models focusing on the role of morphemic units have addressed the issue of how orthographic representations become morphemically structured in the first steps of reading acquisition. Within this framework, the study of the development of reading abilities can be relevant. The present study investigated the role of base frequency in inducing access to morphemic structure information both in young skilled and poor readers, controlling for the grammatical category of the base word, in order to get indications about the lexical information exploited when reading derived words. Method. Twenty 4th and 5th grade poor readers and 40 skilled readers, matched by age, gender and cognitive development, participated in the study. Fifty nouns derived from noun bases and 50 nouns derived from verb bases were employed as experimental stimuli. Each item set was organized in two lists, matched on word frequency and contrasted on base frequency. Stimuli were presented randomly in a reading aloud task, along with four lists of control simple words matched to experimental stimuli for all relevant features. Results. When base frequency was high, nouns derived from noun bases were read by all children more correctly than simple nouns. As for nouns derived from verb bases, though, morphemic parsing did not exert any reliable effect. These results suggest that the facilitating effect of a high frequency base is reduced when its grammatical category is different than the category of the derived word. Data will be discussed in the light of the main computational reading models.