Assessing developmental delay in early childhood — concerns with the Bayley-III scales

Abstract Objective: Early detection of children with developmental delay is crucial for determining which children require close surveillance and intervention services. For many decades, the Bayley Scales has been the most widely used objective measure of early developmental delay, both in clinical and research settings. Significant structural changes were incorporated in the most recent edition, the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). This article reviews the psychometric properties of the Bayley-III and investigates criticisms raised on the Bayley-III, namely that it overestimates developmental status and is a poor predictor of later functioning. Method: This critical review examines the literature on the Bayley-III, which was released in 2006. Results: The Cognitive, Language, and Motor composites of the Bayley-III overestimate development, resulting in an under-identification of children with developmental delay. A range of strategies have been proposed for dealing with the inflated scores on the Bayley-III, none of which are ideal. Evidence to date suggests that the Bayley-III is a poor predictor of later cognitive and motor impairments. Conclusions: The Bayley-III needs new norms, or alternatively, it may be time for a new edition of the Bayley Scales.