Ga-PC/Glr-NA x Reading - significant aptitutde treatement interaction?

Don't the results of this study fall in the domain of a significant aptitude-treatment interaction(ATI)?

Allor, J. H., Fuchs, D., & Mathes, P. G. (2001). Do students with and without lexical retrieval weaknesses respond differently to instruction? Journal of Learning Disabilities, 34(3), 264-275.


Highlights from the article

[Note - adhoc translation to CHC terminology inserted by blogmaster]

• Two phonological processing variables that appear important in predicted future reading performance are phonetic awareness (Ga) nd lexical retrieval (Glr). 264

• Phonemic awareness (Ga-PC)refers to an understanding that words are made up of phonemes; lexical retrieval (Glr - NA?)is the retrieval of phonological codes from long-term memory. 264

• Both descriptive and experimental research suggests that students with deficits in lexical retrieval and phonemic awareness are at considerable risk for experiencing difficulty in learning to read. The purpose of this study was to examine the effectiveness a phonemic awareness and decoding program for first-grade students demonstrating low phonemic awareness. Whereas all students demonstrated low phonemic awareness, their performance varied on lexical retrieval tasks. The reading development of students with relatively high lexical retrieval skill was compared to that of students with relatively low lexical retrieval skill. These comparisons were made to explore the hypothesis that students with weaknesses in both phonemic awareness and lexical retrieval experience greater difficulty in developing phonemic awareness and reading skill than do students who are weak in phonemic awareness alone. 265

• This study analyzed the effects of First-Grade PALS, a phonemic awareness decoding treatment. At the beginning of the study, all students demonstrated relatively low phonemic awareness. Approximately one half of these students also demonstrated relatively low lexical retrieval skill; about half demonstrated relatively high lexical retrieval skill. It was hypothesized that students with a higher level lexical retrieval would respond more favorably to treatment on measures of reading ability than students kith a lower level of lexical retrieval. 270

• We offer two provisional conclusions. First, lexical retrieval seems to influence the development of beginning reading independently of the influence phonemic awareness. This conclusion is consistent with the double deficit hypothesis proposed by several researchers (Blachman, 1994; Bowers & Wolf, 1993; Torgesen et al., 1994)-to wit, students weak in both phonemic awareness and lexical retrieval are at greatest risk for reading difficulty. 273

• Second, students stronger in lexical retrieval skill may respond more favorably to phonemic awareness and decoding training than those weaker in retrieval skills. 273

• In sum, our ESs suggest that the treatment may have helped those with higher levels of lexical retrieval increase their reading ability to a greater degree than it helped those with lower levels of lexical retrieval. A more intensive treatment might have made a stronger impact on students with lower levels of lexical retrieval. 273

• Second, because lexical retrieval appears to provide unique predictive information about the development of beginning reading subskills, precisely how it affects reading needs to studied. The existing evidence is equivocal. Lexical retrieval may differentially affect various reading subkills, or it may simply delay general reading development. Longitudinal information is needed. 274