The relationship between infant state and head Orientation after the head is held in a midline or lateral position was investigated longitudinally in infants 2.4, 8. and 12 weeks of age. Across the four ages, there was a general decrease in the amount of time spent in an active-awake state, whereas the amount of time spent crying remained fairly stable. Overall, infants turned more often to the right than to the left, but this difference was more pronounced when the infants were quietly alert or active-awake than when they were crying. The results thus indicate that state variables inhence the expression of headorientation biases in early infancy.
Internal state is an aspect of the organization and regulation of postnatal behavior that has important implications for understanding normal development. For example, normal newborn infants do better in visual and auditory pursuit tasks when in a quiet-alert state compared to an active-alert state (Wolff, 1966). Similar differences have been reported for older infants when the measure is visual attentiveness to toys (Fischer, 1973; cited in Field, 1981). Consideration of the infant's internal state also may assist in the analysis of abnormal development. For example, Prechtl, Weinmann, and Akiyama (1969) found that it was more difficult to distinguish physiologically between different states in "abnormal" infants than in normal infants, which suggests that state differentiation and responsivity may be impaired in abnormal infants.
In this paper we address the possibility that the infant's internal state also may influence postural orientation, i.e., the direction in which the infant holds its head