Reading Ability, Vocabulary Acquisition and Phonological Processes: An Investigation of Vocabulary Acquistion by Skilled and Less-Skilled Readers
Previous research has found that skilled and less-skilled readers differ in their ability to incorporate aurally encountered words into their personal lexicons. The primary purpose of this study was to corroborate and expand these results. In addition, the present project investigated the associations among reading skill, vocabulary knowledge, and two phonological processes: verbal working memory and lexical access.
Data from 105 fourth-grade students were analyzed for this study. Each student took part in an experimental word learning procedure and completed three memory measures, two lexical access measures, and a test of basic reading skills. Data from subsets of 28 skilled readers and 26 less-skilled readers were analyzed. Reading groups were found to differ in measures of achieved vocabulary, verbal working memory, and on one measure of lexical access. Group differences in experimental vocabulary acquisition were obtained; less-skilled readers required more trials and made more errors in the word learning condition, even when previous vocabulary achievement was statistically controlled. Reading groups also differed on measures of short-term and long-term recall of the phonological content of the words. Groups did not differ in their semantic knowledge of the words.
To better understand the processes underlying these results, data from the entire set of 105 students were analyzed. Reading ability, achieved vocabulary, and underlying phonological processes were evaluated as predictor factors in vocabulary learning. Working memory tasks, along with reading ability, predicted the acquisition task. Reading skill also predicted the other phonologically sensitive task, long-term retrieval. Prior vocabulary knowledge predicted semantic aspects of word retention.
When the achievement measures (i.e., reading and vocabulary) were not entered into the analyses, a complex measure of memory capacity, along with a lexical access task predicted vocabulary learning, as well as performance on the short-term recognition and definition measures. Nonsense word repetition was the most important predictor for long-term retention of the acquired words.
The vocabulary training took place in two sessions. Additional analyses explored the possibility that the groups were deferentially hampered by the first learning task during the second learning session. Both groups demonstrated some interference effects, but the performance of the less-skilled readers was significantly more impaired during the second learning phase. Other post-hoc analyses explored the relative contributions of the phonological processing variables to decoding and word identification. In contrast to studies which used graphological symbol naming as a measure of lexical access, the current study (which used a fairly difficult rapid naming task), did not find that this measure predicted word identification.
Findings support previous research which indicated that skilled and less-skilled readers differ on vocabulary learning, even when words are taught aurally. The pattern of results points to particular difficulty with the phonological aspects of vocabulary acquisition. Performance on verbal working memory and lexical access tasks accounted for modest but significant portions of the variance in new word learning.
These results have implications for both vocabulary and content area instruction with poor readers. Instructional modifications, as well as training in phonological processes which relate to both reading and vocabulary skill, were recommended as potential remedial and instructional tools.