Reading ability and suffix familiarity predict morphological processing in adolescents

Skilled visual word recognition is influenced by morphological structure, as shown by the morpheme interference effect (e.g., Crepaldi et al., 2010), where nonwords with pseudo-morphological structure (‘earist’) are harder to reject as words than matched non-morphemic nonwords (‘earilt’). Less is known about how sensitivity to morphological structure develops, especially during adolescence. Here, we examine the developmental trajectory of the morpheme interference effect during adolescence and investigate whether it is modulated by reading experience. English-speaking adolescents (N= 664, aged 11-17 years) participated in a morpheme interference lexical decision experiment. Reading experience was captured at the individual-level (reading ability) and the item-level (suffix familiarity, as indexed by suffix frequency in children’s reading materials). We observed an overall morpheme interference effect, and the magnitude of the effect was influenced by reading experience such that the effect was more pronounced for better readers and for items with more familiar suffixes. There was some evidence that the effect increases with age. These findings indicate that reading experience shapes the emergence of sensitivity to morphological information in written words, with individual- and item-level factors working together to bring about expertise.