Development of head position preference during early infancy: a longitudinal study in the daily life situation.

We studied developmental changes in supine head position preference in a group of 14 healthy full-term infants from age 3 to 18 weeks. The infants assumed an initial head-right position until 12 weeks. For the maintenance of a head position, a loglinear analysis revealed a developmental trend from an initial head orientation to the right to one with the head in the midline at around 12 weeks. The maintenance of a midline head position was preceded by a marked improvement in postural stabilization, defined as the ability to hold the head upright when seated in an infant chair. The relationship between head position preference and behavioral state changed with age: At 3 weeks all infants maintained the same position regardless of state, but by 18 weeks this situation held for only 64% of those who cried. The implications of these findings for the development of handedness are discussed.