A prospective study of three postural reactions.

In order to assess the evolution of postural reactions in the prone position, a group of 149 normal infants were followed from birth to two years of age. The Landau reflex was present in 44 per cent of two-month-old infants, and in 95 per cent at four months. The tonic labyrinthine response (grades 2 to 4) was seen in 80 per cent of infants at two weeks, with a marked diminution by the age of 24 months. In contrast, the symmetrical tonic neck reflex was detected in fewer than 30 per cent of the infants: the maximum prevalence was at four to six months of age. These findings are consistent with the hypothesis that the Landau is an early righting reflex which emerges after, and is independent of, the tonic labyrinthine response in prone and the symmetrical tonic neck reflex.