Vocabulary measures in concurrent and longitudinal prediction of reading comprehension

Presented at the 16th Annual Meeting of the Society for the Scientific Study of Reading, Boston, MA, 25–27 June 2009

Athanassios Protopapas,1 Panagiotis G. Simos,2 Georgios D. Sideridis,2 & Angeliki Mouzaki3
1 Institute for Language & Speech Processing / “Athena” Research Center, Greece
2 Department of Psychology, University of Crete, Greece
3 Department of Primary Education, University of Crete, Greece

Purpose: In the relatively transparent Greek orthography, vocabulary measures take up most of reading comprehension variance accounted for by print-related measures. Here we extend previous work by concurrent and longitudinal multiple linear regression analyses of reading comprehension. Method: Data from 516 children in Grades 3, 4, and 5 included measures of vocabulary (V: PPVT & WISC-III), word identification (W: accuracy and fluency), pseudoword decoding (D: accuracy and fluency), reading comprehension (RC) and auditory comprehension (A). Results: V accounted for 22% of total concurrent RC variance (after age, grade, and WISC blocks), more than A (11%), W (14%), or D (8%); V also accounted for more unique variance (entered last: 7.6%) than A (1.6%), W (1.6%), or D (.3%). In the longitudinal prediction of RC one year later (data from 482 children), V was the strongest predictor either without (22%) or with (6.3%) an RC autoregressor (compared to A: 14% and 4.9%; W: 13% and 3.2%; D: 8% and 2.1%), accounting for most unique variance (7.0% and 2.7%, respectively, compared to A: 2.9% and 2.0%; W: .8% and .3%; D: .2% and .1%). Including text fluency (words per minute) substantially increased the concurrent but not the longitudinal prediction of RC. Conclusions: These results are interpreted in the context of the lexical quality hypothesis, suggesting that the simple view may be too simple to capture the development of sight-word reading. Moreover, vocabulary measures seem to assess more than depth and breadth of word knowledge, perhaps due to experience with visual word recognition.