Research conducted with monolingual adults indicated a correlation between WM task performance and reading and listening comprehension (Baddeley, 1986; Campbell, Dollaghan, Needleman & Janosky, 1997; Cowan, 1996; Daneman & Carpenter, 1980; Just & Carpenter, 1992; Weismer, Evans & Hesketh, 1999).
Gathercole et al. (2004) indicated, however, that the contribution of WM to scholastic attainment varies considerably across the school years with WM having a greater influence on children‟s emerging literary skills during the early years of learning to read and write.
In the L1 group the only significant correlation was between VS-WM (r = 0.43, p = 0.02) and reading-comprehension. The results for the regression analysis showed that there was one contributing factor, VS-WM which accounted for 19% of the variance in
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reading comprehension. In reading comprehension the reader must first extract and
decode words before trying to make sense of their meaning. Hence decoding plays an important part in reading comprehension. At Grade 1 level most learners are in Ehri‟s (2005) partial alphabetic phase and have not completely developed their reading skills and this would, in turn, impact on their comprehension ability. At this stage of reading development, learners are more dependent on visual codes than more advanced
readers. According to Samuels (1994) beginner readers who have not yet achieved automaticity switch attention between decoding and comprehension in order to process text. Beginner readers rely more heavily on the Visual Memory component of the LaBerge-Samuels model than a more advanced reader since they decode more.
Swanson and Howell (2001) found a significant correlation between reading comprehension and a composite linguistic measure as well as to a composite visuo- spatial measure. In the study they looked at a group of 9 year olds and concluded that both V-WM and VS-WM contributed to the performance of reading comprehension. How is it then that VS-WM is a constraining factor in reading comprehension in this study while V-WM was not? The answer lies in the particular stage of reading competency that these learners were probably at. The visuospatial domain is
implicated because of partially developed reading skills. In other words, VS-WM is being filled with the partial products of decoded words while the learner attempts to read these words. The amount of words the learner can decode in a given time impacts on the learner‟s level of comprehension of a given text. Thus it is that their VS-WM indirectly affects and constrains reading comprehension. Hence, although V-WM and VS-WM usually impact on reading comprehension, in this group VS-WM becomes “filled up” before V-WM does and therefore VS-WM is the constraining factor.
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In the L2 group reading-comprehension was highly correlated with V-WM (r = 0.747, p < 0.001) and V-STM (r = 0.67, p <0.001) and moderately correlated with VS-STM (r = 0.392, p = 0.03) and VS-WM (r = 0.477, p = 0.01). In addition, 56% of the variance could be explained by the V-WM predictor while V-STM accounts for only 5% of the variance. In striking contrast to the L1 group where the visuospatial domain
contributed the most variance, the verbal domain seems to be the constraining aspect in the L2 group.
The results agree with previous studies implicating V-WM and V-STM as variables that constrain comprehension in bilingual learners. Ardila (2003) noted that in bilinguals, brain activation patterns during WM tasks are observed to be more
complex when L2 is being used suggesting that processing information in L2 is more demanding. WM may be less efficient when processing information in L2 since semantic search in L2 takes longer than it would for a monolingual. This serves to functionally decrease the capacity of WM available for processing.
The reason for this according to Kroll and de Groot (1997, as cited in McElree et al., 2000) is that in the early stages of L2 acquisition (as is the case with the unbalanced bilinguals in the L2 group), links between the L2 lexicon and the conceptual store are non-existent to weak and the primary means for L2 semantic processing is by
translation to L1. Hence the same limited resources (verbal WM and verbal STM) are being used for semantic search and for reading comprehension in bilinguals. Memory resources in the verbal domain are therefore the constraining factor in the L2 group
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since both storage and processing resources are utilised for reading comprehension and for L2 language use.
In terms of the aims of the study it would appear that a correlation between working memory and reading comprehension as shown in previous studies (Baddeley, 1986; Campbell, Dollaghan, Needleman & Janosky, 1997; Cowan, 1996; Daneman & Carpenter, 1980; Just & Carpenter, 1992; Weismer, Evans & Hesketh, 1999) has been reproduced in each of the groups. However, since the current study utilised a measure that allowed for the composite memory scores to be broken up into four constituent parts, the results pointed to differences in which specific aspects of memory are correlated with reading-comprehension in each group. In the L1 group, the
correlations are weak to moderate and the only significant correlation is between VS-
WM and reading comprehension. In the L2 group, the correlations are moderate to
high and all the correlations are significant. This might indicate that the entire memory system is utilised more by the L2 group as a result of the additional processing that takes place due to the use of two languages as well as the particular stage of reading proficiency that these learners are at.