In the experiment reported in chapter 6, sensitive testing revealed a considerable increase in E's vocabulary knowledge after she encountered target words that occurred two, three or four times in a German novella. The experiments with R and W, which were carefully designed to isolate the effect of each reading encounter, used the sensitive testing technique to trace growth over the course of many encounters with hundreds of target words. There were six main findings. .
First, both R and W's knowledge of target words increased demonstrably as a result of multiple encounters. In both cases, the number of words the participants rated 0 (don't know) decreased dramatically by the end of the experiment. Much of the growth involved acquiring partial knowledge of words. Secondly, much of the total growth that was eventually reported - after ten textual exposures in the case of R, and after eight in the case of W - had already occurred in the early stages of the experiments. W's gains after reading Lucky Luke just twice were especially striking. Thirdly, modeling both participants' growth as matrices revealed that word knowledge was not stable; with repeated contextual encounters, the learners appeared to lose and regain word knowledge in a manner that is consistent with learning through hypothesis testing. The fourth finding was especially intriguing: the probability matrices based on growth after just one reading encounter proved to predict the growth effects of subsequent encounters surprisingly well for both R and W. Fifth, comparison of these two experiments indicated that more growth occurred when the reading treatment included illustrations. Finally, the investigation reported in the previous chapter revealed that word characteristics (importance to the events of the story and informativeness of verbal and picture support) could not account for the vocabulary knowledge gains R and W reported.
