Date of Award:

5-2013

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Special Education and Rehabilitation

Committee Chair(s)

Ronald B. Gillam

Committee

Ronald B. Gillam

Committee

Sandi Gillam

Committee

Tim Slocum

Committee

Jamison Fargo

Committee

Ray Reutzel

Abstract

This study investigated the unique contributions of simple and complex auditory-verbal and visuospatial working memory (WM) in isolation or in conjunction with other skills known to affect decoding such as phonological awareness, orthographic knowledge, and nonverbal and verbal intelligence. Thirty-two second-grade students and 22 fifth-grade students, all identified as poor decoders, participated in this study.

For the second-grade students, a measure of complex auditory-verbal WM was correlated with word attack (reading psuedowords). For fifth-grade participants, there was a negative correlation between a complex visuospatial WM measure and word attack. A measure of simple auditory-verbal WM was correlated to word identification (reading real words) in fifth grade.

Different combinations of WM measures predicted word identification and word attack ability in second and fifth graders. Second graders appeared to rely more on the processes involved in auditory-verbal WM when identifying words, while fifth-grade students relied on the visuospatial domains to identify words. For second-grade students, both complex visuospatial and auditory-verbal WM predicted word attack ability, but by fifth grade, only the visual domains predicted word attack.

It appears that the storage and attentional control mechanisms in working memory make differential contributions to decoding at second and fifth grade. For second graders, it was a complex auditory-verbal WM measure that required high cognitive control that was most predictive of word identification. The auditory-verbal WM measure that required high cognitive control also was predictive of word attack in second-grade students. The second-grade students were still utilizing the phonological loop to sound out real words, so it makes sense that a measure that requires equal amounts of attentional control and storage would be related to decoding. The complex visuospatial WM measures negatively predicted word attack in these students, suggesting that higher visuospatial capacity was a hindrance to decoding pseudowords. This may have happened because the second-grade students had large visuospatial WM capacities, but they were significantly impaired in their decoding skills. They were not at the stage in their reading development to utilize their visuospatial WM resource efficiently. At this stage in their development, second graders need to be explicitly taught to attend to graphemic and phonemic cues, hold the focus of their attention on critical information for longer periods of time, and then shift their attention back to critical information when it is necessary.

In fifth-grade students, we saw a shift from reliance on auditory-verbal WM to visuospatial WM. It was orthographic knowledge that best predicted word identification in fifth-grade students, suggesting that at this grade level, decoding primarily involves identifying word patterns rather than sounding out words one phoneme at a time. In fact, we saw that fifth-grade students did not attempt to sound out unfamiliar words. This change in the influence of WM on decoding may relate to a curricular change as students go from “learning to read” to “reading to learn.”

Similar to the second-grade students, the visuospatial WM measures negatively predicted word attack scores in the fifth graders. This finding indicates that when there is a large discrepancy between visuospatial WM and decoding abilities, the visuospatial WM actually impedes reading performance. These students may be so dependent on identifying words by sight, that when they encounter a pseudoword not available in their large repertoire of stored representations, they become discouraged and cease trying to decode the word.

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