All in the (word) family:

In this paper, we use the method of learning decomposition to study students’ mental representations of English words. Specifically, we investigate whether practice on a word transfers to similar words. We focus on the case where similar words share the same root (e.g., “dog” and “dogs”). Our data comes from Project LISTEN’s Reading Tutor during the 2003—2004 school year, and includes 6,213,289 words read by 650 students. We analyze the distribution of transfer effects across students, and identify factors that predict the amount of transfer. The results support some of our hypotheses about learning, e.g., the transfer effect from practice on similar words is greater for proficient readers than for poor readers. More significant than these empirical findings, however, is the novel analytic approach to measure transfer effects.