Executive functioning in preschool children : utility of two new instruments

Executive Functioning skills develop with age, emerging in infancy and becoming established in early adulthood. Despite the considerable attention given them in child, adolescent and adult research, they have received only minimal attention in research with preschool age children. Many disorders of childhood begin to present themselves as the child begins to emerge from the largely non-verbal world of the toddler. The lack of research in this age group presents a very real problem for clinicians wanting to characterize disorders in time to begin early intervention programs. This study aims to contribute to a greater understanding of executive functioning in the preschool age group, by evaluating two developmentally appropriate instruments with an Australian sample. Thirty-three normally developing preschool children between the ages of 54 and 66 months were tested using two recently developed, preschool specific neuropsychological tests of executive functioning; Espy's (1997) Shape School Task (SST) and Byrne's et al., (1998) Picture Deletion Task for preschoolers (PDTP). Results showed consistency between U S and Australian data on measures of inhibitory control using the SST, but not on measures of mental flexibility. Results from the PDTP showed high levels of variability within the US and Australian samples and quite large discrepancies between US and Australian performances, particularly with regard to omission errors. The absence of IQ data and limited methodological detail in the US studies made comparison of results difficult to interpret. Additional analysis was undertaken on the Australian sample with the division of the group into two separate cohorts of 54-59 and 60-66 months of age. As expected, there were no developmental trends evident between the younger and the older age groups, suggesting that spurts in the development of impulse control and mental flexibility are most noticeable prior to the age of four years. It was concluded that in particular the SST showed promise as a tool for assessing aspects of executive functioning in preschool age children, but that the PDTP with its greater variability requires further refinement. Both tasks would benefit from further investigations with both normally developing children over a wider age range, and with clinical samples. The application of these instruments in two clinical case studies are also presented