Chapter 2 Research hypotheses

In this section, I outline the main hypotheses I plan to examine for each study. This section is intended to preregister the main analyses for this project.

Study 1: Familiar word recognition and lexical competition

• Children’s accuracy and efficiency of recognizing words will improve each year.

• There are stable individual differences in lexical processing of familiar words such that children who are relatively fast at age 3 remain relatively fast at age 4 and age 5.

• However, the magnitude of these individual differences diminishes over time, as children converge on a mature level of performance for this paradigm.

• Consequently, individual differences in word recognition at age 3, for example, will be more discriminating and predictive of age-5 language outcomes than differences at age 4 or age 5.

• Children will become more sensitive to lexical competitors as they age, based on the hypothesis that children discover similarities among words as a consequence of learning more and more words.

• Children will differ in their sensitivity to lexical competitors, and these individual differences will correlate with other child-level measures.

Study 2: Referent selection and mispronunciations

• Children’s accuracy and efficiency of recognizing real words and fast-associating nonwords will improve each year.

• Performance in real word recognition and fast association of nonwords will be highly correlated, based on the hypothesis that the same process (referent selection) operates in both situations.

• Under the alternative hypothesis, real word recognition and fast referent selection reflect different skills with different developmental trajectories. Thus, if there is any dissociation between recognition of real words and nonwords, it will be observed in younger children.

• Although these two measures will be correlated, I predict performance in the nonword condition will be a better predictor of future vocabulary growth than performance in the real word condition. This hypothesis is based on the idea that fast referent selection is a more relevant skill for learning new words than recognition of known words.

• For the mispronunciations, I predict children with larger vocabularies (that is, older children) will be more likely to tolerate a mispronunciation as a production of familiar word compared to children with smaller vocabularies.

• Mispronunciations that feature later-mastered sounds (e.g., rice-wice) will be more likely to be associated to novel objects than earlier-mastered sounds (duck-guck).