Preliminary evaluation of an adapted snack delay task for measuring inhibition in young children with Down syndrome.

BACKGROUND: Individuals with Down syndrome (DS) often experience challenges in executive functioning (EF), including inhibitory control. Despite interest in EF research and intervention in DS, there is a lack of feasible and developmentally sensitive measures of EF for young children in this population. This study evaluated the feasibility, developmental sensitivity, and test-retest reliability of a modified Snack Delay task for children with DS aged 2-7 years. METHODS: The Snack Delay task was administered to 118 participants with DS (mean age = 5.21, SD = 1.53; 51.7% male). Three outcome metrics were evaluated for feasibility, developmental sensitivity, and preliminary psychometric properties. Feasibility was assessed by task completion rates. Distributional characteristics, including range and floor and ceiling effects, were examined. Intraclass correlation coefficients assessed test-retest reliability, and t-tests evaluated practice effects across a two-week period. Developmental sensitivity was evaluated as a function of chronological and mental age. RESULTS: The Snack Delay task was feasible for 89% of participants and captured meaningful variability in inhibitory control among children with DS aged 3-7 years. Floor effects ranged from 0% to 17.1% and ceiling effects from 20% to 56.2%. Test-retest reliability was moderate for one metric and strong for two. A small, non-significant practice effect was observed for one metric, with lower average waiting times at retest. Performance scaled with age and developmental level, though ceiling effects were observed in older children. Lack of motivation was more common among participants with younger chronological and mental ages. CONCLUSION: The Snack Delay task is a reliable, developmentally sensitive measure of inhibition in young children with DS and may be a valuable tool for assessing EF in this population.