Like most animals, humans rely on their five senses to experience the world around them. These senses--sight, taste, touch, smell, and hearing--allow each individual to interpret his or her environment; this is called sensory processing. The growth of these senses is known as sensory development.
This process starts during gestation. From birth, a child can begin to explore each of his or her senses. All five senses are not yet completely developed; sight in particular is very limited following birth. It is during this period of infancy when childhood sensory development begins to progress.
As the sense of touch is key in the bonding process between baby and caregiver, touch sensory development is normally well-developed during infancy. Newborns often respond to touch in a similar fashion to adults. Babies vary in the amount of touch they can tolerate. During childhood, children often explore their sense of touch through their sensitive tongues, which is why so many children place objects in their mouths.
Exploration through the mouth is also a form of taste sensory development. Babies are typically born with a preference for mildly sweet tastes, such as breast milk. As they explore more tastes, their tolerance for various flavors develops.
Hearing sensory development is usually well underway within the womb. Fetuses can hear the mother's bodily noises as well as loud noises, such as car horns, outside her body. The most familiar sound to a baby is typically his or her mother's heartbeat, which often provides a soothing during moments of distress.
An infant's sense of smell develops within the womb as well. Fetuses recognize the smell of their mother's amniotic fluid. As with touch, a baby can recognize his or her mother through the sense of smell. The smells of other family members the baby comes into contact with daily also become familiar quickly, helping the baby identify different people.
Sight development occurs slowly at first. As a newborn, a baby can see objects within eight to ten inches (20 to 25 centimeters) of his or her face. The first sight a baby normally learns is the face of his or her primary caregiver. Though other colors remain vague during the first few weeks of life, white, black, and red are easily distinguished. As the infant grows, so does his or her range of sight.
Though sensory development is a natural process for most babies, sometimes complications can occur. This is known as sensory integration dysfunction. Various circumstances, such as prematurity, can lead to this dysfunction. Sensory integration dysfunction usually results in either too much or too little sensory input from his or her environment. Physical and occupational therapy can be used to help improve, or even correct, this condition.