Psychology 101: Intro to Psychology

Why are some senses more developed than others for a newborn? You'll learn which senses are initially important for infants to bond with and recognize their mothers and which one is still in development after birth.

Just like the other systems in our bodies, our senses develop in stages over time. Infants are born with enough sensory abilities to get by; these abilities get more sophisticated as infants grow. A newborn doesn't need to see things very clearly, because its immediate concerns are feeding and bonding with its mother. But later, vision becomes crucial to learning and exploring the world. For efficiency's sake, infants stay in the womb long enough to develop crucial skills and fill in the rest soon after being born.

Newborns have very poor vision; estimates range from 20/120 to 20/400. This means that to see an object that an adult with normal 20/20 vision can see, the newborn would need the object to be 6-20 times closer or more magnified. If presented with an eye chart from a normal distance, they would only be able to distinguish the large letter E at the top. They don't have good vision in part because the part of the eye that deals with details, called the fovea, isn't completely developed at birth. This grows enough to give infants 20/20 vision by around two years of age. Since the fovea is also responsible for color vision, infants have difficulty distinguishing between really similar colors like pastels. In general, infants have less sharpness in their vision, in terms of both shape and color.

It's really important for infants to be able to recognize their mothers, so their senses of hearing and smell are developed to this purpose early on. Babies can hear before they're even born and learn the sounds of their mother's voice, and of the language she speaks, while they're still in the womb. Once they're born, they prefer her voice above all others. They also prefer songs or stories that they've heard before birth, because the patterns and sounds are familiar to them.

When it comes to smell, infants at birth prefer the scent of their mothers to other people. They seem very sensitive to human smells like this one but not to the majority of smells that they'll be able to detect as adults. By the age of three, toddlers seem to have developed similar scent preferences as adults, so their ability to distinguish between scents is thought to have greatly improved by this age.

An infant's senses of touch and taste seem to be mature at birth. Touch is actually really important to infants' early happiness; they sleep better and cry less when they have frequent skin-to-skin contact with their mothers.

In general, infants tend to prefer sweet tastes to others. Our senses of taste generally change as we age--we often 'learn to like' foods we would reject as children, like bitter coffee--but all of the mechanisms of taste are present in newborn infants.

To review, infants' senses are in different states when they're first born. Their eyesight isn't very developed because they don't need it in their early weeks; their hearing, touch and smell are developed in order to facilitate better communication and bonding with their mothers. Their sense of taste is largely developed, though preferences still change over time.