Development of directed global inhibition, competitive inhibition and behavioural inhibition during the transition between infancy and toddlerhood

Inhibitory control (IC) is a core executive function integral to self-regulation and cognitive control, yet is itself multi-componential. Directed global inhibition entails stopping an action on demand. Competitive inhibition is engaged when an alternative response must also be produced. Related, but not an executive function, is temperamentally-driven wariness of novelty, known as behavioural inhibition. Understanding early development of these components has been hampered by a shortage of suitable measures. We combine established and novel measures to capture directed global inhibition (Toy Prohibition, Touchscreen Prohibition), competitive inhibition (A-not-B, Early Childhood Inhibitory Touchscreen Task; ECITT) and behavioural inhibition (Touchscreen Approach) in 113 10- and 16-month-olds (73 seen longitudinally). Pre-registered analysis of ECITT performance shows good 1-week test-retest reliability at 10 months (r=.30-.60). Ten-month performance on directed global inhibition measures shows little stability to 16-months, and may be primarily influenced by behavioural inhibition. Performance on measures targeting similar IC components shows greater coherence at 16 months (r=.23-.59) compared with 10 months (r=.09-.35), and developmental progression across this period. Probing of ECITT condition effects indicates toddlers are more able, compared with when they were infants, to override immediate prepotencies; indicative of increasingly flexible control over behaviour. However, exerting inhibitory control over cumulative prepotencies appears to be just as challenging for toddlers as infants. Exploratory analyses (requiring replication) indicate reciprocal associations between behavioural and competitive inhibition across infancy into toddlerhood, yet limited cross-sectional associations. In combination, these study findings provide new insights into IC development across the under-studied yet key transition between infancy and toddlerhood.