A newborn's world is a very different place than an adult's world largely because the infant's sensory apparatus is not yet mature. The world may look like a very fuzzy place to babies because their ability to focus their eyes has not yet developed. Likewise, their sense of touch is far more sensitive than adults' sense. Parents should take infants' sensory development factors into account so they can keep babies comfortable.
Types
Sensory development in infants involves the growing ability to taste, smell, touch, see and hear. The New York Times includes vestibular or inner ear senses among the traditional senses. Vestibular senses allow the infant to sense positional changes such as rocking. Proprioception--or the sense of knowing where one's body is in space--derives from all of these.
Vision
Vision is one of the least-developed senses at birth. The American Optometric Association reports that "babies learn to see over a period of time, much like they learn to walk and talk." Focusing the eyes, moving them as desired and using them together are learned skills. When a baby is born, his focal length is roughly 8 to 10 inches from his face--which is the location of mom's face when the infant is nursing. The American Optometric Association explains that by 3 months of age, babies begin to visually track moving objects.
Hearing
Hearing develops when the baby is still in the womb. The New York Times reports that unlike vision, the sense of hearing is mature at birth. Infants have distinct preferences for certain sounds. They startle at sharp abrasive noises and become soothed at the sound of mom's voice.
Taste and Smell
"Parents" magazine reported on the the developing sense of taste in infant, noting babies detect three distinct tastes--sweet, sour and bitter--right after birth. Curiously, infants are unable to taste salt. UCLA psychology researcher Phil Kellman reports that infants will drink just as much salt water as fresh water. He speculates that salt receptors on the tongue are not developed until the baby is 4 months old.
The sense of smell develops largely after birth, but babies recognize certain smells, such as their mother's scent, within the first week of life.
Testing
According to the American Speech-Language-Hearing Association, as of 2010, audio screening of a newborn before he leaves the hospital is becoming more common. Without this initial screening, hearing deficits are not usually detected until about 14 months of age. Such undetected deficits result in problems with language development and learning.
Testing the vision of infants under 3 years involves a physical examination of the eye and determining whether the child's vision can fix on a particular object and track it when it is moving. Failure to develop this ability by 3 months raises the possibility of eye or brain abnormalities. The American Optometric Association recommends having the first eye exam at age 6 months.
Misconceptions
A 2001 issue of the "Journal of the American Academy of Pediatrics" speaks to the misconception that infants do not feel pain the way adults do. This misconception has led to a lack of pain assessment in children. The panel of authors, who belong to the Committee on Psychosocial Aspects of Child and Family Health and the Task Force on Pain in Infants, Children and Adolescents, urge that infant pain be treated compassionately by preparing family members to be supportive and providing pain medication as needed.
References
- American Optometric Association: Infant Vision: Birth to 24 Months of Age
- American Speech-Language-Hearing Association: Hearing Screening
- New York Times: Infant - Newborn Development
- "Journal of the American Academy of Pediatrics": The Assessment and Management of Acute Pain in Infants
- "Parents": Your Newborn's Developing Senses
