Assessment of Executive Function in Infants and Toddlers: A Potential Role of the Bayley-4

Objective: The development of executive function (EF) in infants and toddlers has received increased interest by clinicians and researchers. Higher rates of deficits in EF have been reported in at-risk groups of infants such as those born extremely preterm. These deficits play an important role in the etiology of early neurodevelopmental problems and are predictive of subsequent nonoptimal educational outcomes. In this study, the Bayley-4 is used to follow the developmental course of EF and to determine whether EF is a unitary concept or can be parsed into discrete components over the first 42 months.

Method: All 81 cognitive items from the Bayley-4 normative sample of 1700 infants and toddlers were classified a priori into 6 EFs, and then, 5 age groups derived from Bayley-4 start points were factor analyzed to determine at what age EFs emerge and to address the controversy of whether the factor structure of the cognitive items for each of 5 age groups reflect a single factor or multiple factors.

Results: Bayley-4 items form 1 to 5 EF factors for each age group, accounting for 59% to 74% of the variance. There is a developmental progression in EF as well. The results indicate EF constructs can be identified early.

Conclusion: Executive function tasks in infants and toddlers are interrelated with task content either remaining the same or changing with advancing age (i.e., content that is homotypic or heterotypic, respectively). EFs measured by Bayley-4 items are useful clinically and become more complex with increasing age, corresponding to more advanced brain development and integration. The findings have the potential of providing additional information in the assessment of infants at risk such as those born preterm.