Reflexive Movement Phase
The very first movements are reflexive. Reflexes are involuntary, subcortically controlled movements. Through reflex activity the infant gains information about the immediate environment. The infant's reactions to touch, light, sounds, and changes in pressure trigger involuntary movements. These movements, coupled with the increasing cortical sophistication in the early months of life, play an important role in helping the child learn more about his or her body and the outside world, and are typically referred to as primitive reflexes and postural reflexes.
Primitive reflexes are information gathering, nourishment seeking, and protective responses. Postural reflexes resemble later voluntary movements and are used to support the body against gravity or to permit movement. See Tables 16.2 and 16.3 for a summary of common primitive and postural reflexes, respectively. The reflexive movement phase may be divided into two overlapping stages.
Information Encoding Stage
The information encoding (gathering) stage of the reflexive movement phase is characterized by observable involuntary movement during the fetal period until about the fourth month of infancy. During this stage lower brain centers are more highly devel than the motor cortex and are essentially in