["Journal of Intellectual Disability Research, EarlyView. ", "\nABSTRACT\n\nBackground\nThe Cat/Dog Stroop task is a modification of the original Stroop task as a measure of cognitive inhibition frequently used in studies of individuals with Down syndrome (DS). There is great heterogeneity in scoring mechanisms for this task and similar Stroop tasks, potentially impacting convergence of and interpretation of study findings. We review scoring mechanisms used with the Stroop task in the general population and those that are used among individuals with DS to evaluate the strengths and weaknesses of these scoring mechanisms in this population.\n\n\nMethod\nWe reviewed the literature to identify current scoring mechanisms used for the original Stroop task and for the Cat/Dog Stroop task among individuals with DS. Using a sample of 146 children and adults with DS ages 6–29 years who completed the Cat/Dog Stroop, we independently modelled the identified scoring mechanisms. Scoring mechanisms were assessed for skew, kurtosis and normality as assessed through the Anderson–Darling test with the full sample and by age bands.\n\n\nResults\nEight distinct scoring mechanisms were identified that could be used with the conditions present in the Cat/Dog Stroop task. Six of these eight scoring mechanisms had been used in studies of individuals with DS, with the remaining two mechanisms not yet applied to Cat/Dog Stroop in individuals with DS. Of these scoring mechanisms, one mechanism consistently emerged across stratified age groups as approximating normality for the Cat/Dog Stroop task based on skewness, kurtosis and tests of normality in a sample of individuals with DS.\n\n\nDiscussion\nFor consistency in how the Cat/Dog Stroop task is scored for children and adults with DS, we recommend that the number of correct responses in the incongruent condition should be divided by completion time in the incongruent condition. Additionally, for adults, incongruent completion time minus the congruent completion time or incongruent completion time divided by congruent completion time may also be appropriate.\n\n"]