The development of executive function in childhood

The experiments in this thesis explored the development of executive function in 5- to 11-year-old children. Developmentally-appropriate versions of the task-switching paradigm, go/no-go task and self-ordered pointing test were used to measure shifting, inhibition and working memory respectively. These executive skills were examined independently and within-task experimental manipulations were used to explore both the executive and non-executive processes that influenced children’s performance. These allowed the investigation of not only when, but also how executive function develops. It was found that shifting development, as measured by the task-switching paradigm was highly influenced by the specific tasks switched between and the conflict created by the overlap of the tasks, as well as by previous task experience. Working memory for pictures was also influenced by previous experience and task difficulty, however the predicted relationship between memory for nameable objects and language ability was not found. Inhibition on the go/no-go paradigm appeared to be driven by an improvement in the efficiency of response inhibition enabling older children to inhibit a response at an earlier stage during the movement. Shifting, inhibition and working memory all showed developmental improvements during mid-childhood, demonstrating the protracted development of executive function. Shifting and working memory showed a similar pattern of development whereas inhibition reached a stable level of performance at an earlier age. There were no correlations between the three executive skills studied in this thesis, supporting the fractionation of executive function