Protracted development of motor cortex constrains rich interpretations of infant cognition

Cognition in preverbal human infants must be inferred from overt motor behav-iors such as gaze shifts, head turns, or reaching for objects. However, infant mammals - including human infants - show protracted postnatal development of cortical motor outflow. Cortical control of eye, face, head, and limb move-ments is absent at birth and slowly emerges over the first postnatal year and be-yond. Accordingly, the neonatal cortex in humans cannot generate the motor behaviors routinely used to support inferences about infants' cognitive abilities, and thus claims of developmental continuity between infant and adult cognition are suspect. Recognition of the protracted development of motor cortex should temper rich interpretations of infant cognition and motivate more serious consid-eration of the role of subcortical mechanisms in early cognitive development.

Automated summary

Cognition in preverbal human infants is inferred from overt motor behaviors, such as gaze shifts, head turns, or reaching for objects. However, infant mammals, including human infants, show prolonged development of cortical motor outflow. The neonatal cortex in humans lacks the ability to generate motor behaviors that can support inferences about infants' cognitive abilities, challenging claims of developmental continuity between infant and adult cognition. Recognizing the protracted development of the motor cortex should lead to a more cautious interpretation of infant cognition and encourage further consideration of subcortical mechanisms in early cognitive development.