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Eye-tracking movements and mental attentional capacity in children and adults
Eye-tracking is a non-invasive measure that has been repeatedly used for studying attention and related cognitive processes. While eye-tracking is not a direct measure of brain activity, it has been shown to reveal information about mental processes, that may not be easily accessible through other measures, such as problem solving strategies. Mental attentional capacity corresponds to the amount of information an individual can maintain and manipulate in mind (Pascual-Leone, J. ,1970); it is considered the central maturational component of working memory (Arsalidou, M., Pascual-Leone, J., & Johnson, J. ,2010). This construct has been found to be closely related to other aspects of cognitive competence and intelligence (Johnson et al., 2003). Research into relation between eye movements and mental attentional capacity across development at the moment is sparse and fragmented and no eye tracking studies have been conducted so far with parametric developmental measures, such as the colour matching tasks (Arsalidou, M., Pascual-Leone, J., & Johnson, J. ,2010), which would allow to dissociate changes in saccades and fixations related to working memory load (n = 6) from those related to interference control and trace the maturation of these two processes. The purpose of this study is to investigate the relation between eye-tracking indices (e.g., number of fixations) and mental attentional capacity. Data from adult participants showed significant differences between number of fixations per trial for different levels of mental attentional load. Additionally, analysis revealed significant negative correlation between number and duration of fixations and accuracy for both the balloons and the clowns versions of the task, with the correlation being stronger for the clowns version, which contains interference. Interestingly, for each difficulty level, children generate a similar number of fixations regardless of interfering features, whereas adults make fewer fixations when the task has less interfering features. This suggests that adults may have different strategies depending on the task. Increased number of fixations may indicate that children favor a visual-spatial strategy, whereas adults favor a verbal strategy.