While most of the time they are sleeping, they are still aware of and sensitive to their environment. Crying is the primary method of communication for the infant's needs and emotions. Infants from one to twelve months continue to learn continuously during waking hours as newly acquired skills are used to explore and gather information from the infant's environment. During the first few months, an infant's growth proceeds at a rapid pace. Body systems become fairly well stabilized with temperature, breathing patterns, and heart rate becoming regular.
Motor skill improves as strength and voluntary muscle control increase.
Social responsiveness begins to appear as infants practice and enjoy using their eyes to explore the environment. As social awareness develops, infants gradually establish a sense of trust and emotional attachment to parents and caregivers. Crying continues to be the primary form of communication, however more complex communication skills are gradually emerging as infants enjoy imitating speech sounds and gestures of others. Between four to eight months infants are developing a wide range of skills and have a greater ability to use their bodies. J Infants are now able to manipulate and mouth toys and other objects that they come in contact with.