Working memory is a system devoted to the maintenance of information in the service of complex cognitive processing and is conventionally measured using complex memory span tasks. Developmental memory research has examined how mechanisms such as short-term memory storage, processing efficiency, retention duration, and focus of attention (i.e., limited attentional resources for activating contents of working memory) constrain complex memory span. There continues to be a need, however, for the examination of specific attention control mechanisms in children's complex memory span performance.

This dissertation examined the role of two attention control mechanisms; sustained attentional focus and attentional focus switching, in typically developing 7- to 11-year-old children's complex memory span performance. Sustained attentional focus was explored because of suggestions in the literature implicating its importance to higher-order cognitive functioning. Sustained attentional focus may be critical to complex memory span performance because there is a need to maintain general vigilance over multiple steps in a complex memory span task. Attentional focus switching was assessed because emerging data in the adult literature suggest that it predicts performance on complex memory span. It appears that individuals rapidly switch their focus of attention between storage and processing while performing complex memory span tasks. Efficient attention switching thus improves complex memory span.

Children's sustained attentional focus was indexed by their ability to maintain attention over time on the standardized vigilance measures from the Gordon Diagnostic System. Using experimental measures, attentional focus switching was indexed by the accuracy and speed to switch the focus of attention between two different simple stimuli. Two measures were used for each of the predictor constructs (sustained attentional focus, attentional focus switching) and the dependent variable (complex memory span). General Linear Modeling procedures revealed that, when controlling for age effects, only attentional focus switching accuracy emerged as the significant predictor of children's complex memory span in the present study. Results are in strong agreement with the adult literature implying the critical role of attentional focus switching in working memory. The present study is the first to explicitly examine the contribution of attentional focus switching to children's complex memory span. Additionally, these results substantiate data that further elaborate aspects of domain-general executive attention in developmental working memory models.