The Science Behind Your Baby’s Smile
March 26, 2021Ever wonder what makes your baby smile? Scientists have studied how babies learn facial expressions, and the findings may surprise you.
Smiling and Social Development
Sometimes the early smiles babies make are attributed to “just gas,” but scientists now believe there may be more to a baby’s first smiles than meets the eye.
According to researchers, a baby’s smile can indicate a range of clues toward their social and emotional development starting almost right after birth. Furthermore, the types of responses your baby gets after making certain facial expressions could leave a lasting imprint on their social responses.1
Probably the most significant development from studying babies’ smiles is the discovery that by the time a baby is four months of age, both the baby and mother time their smiles in a purposeful, goal-oriented manner.2 The discovery was made in a 2015 study at the University of California San Diego. During the study, scientists programmed a baby-like robot to smile at undergraduate volunteers in the same patterns they had observed in real-life 4-month-olds and their mothers. By calculating the statistics they gathered from their recording of the experiment, the scientists were able to determine that while mothers timed their smiles to maximize mutual smiling, the infants were likely timing their smiles to maximize mother-only smiling. In other words, whether the infants knew it or not, they were smiling just enough to keep their moms smiling.2
Stages of Smiling
Depending on your baby’s age, their smile could mean different things. Here’s a timeline of how your baby’s smile develops over time.
0-6 Weeks – Reflexive Smile: This is most noticeable when your baby sleeps. Your baby goes through a lot of physiological changes during REM sleep, activating certain reflexes. One of those reflexes is to smile.3
6-8 Weeks – Responsive Smile: Your baby may begin to smile in response to certain stimuli at this point. Voices, faces, and noises, especially those that your baby associates with his primary caregiver, will likely produce a smile.3
2-3 Months – Social Smile: Up to this point, your baby’s smile has mostly been attributed to internal reactions to things that make them feel pleasure or comfort, or a reflex. Now that begins to change, as your baby learns that their smile can get a reaction and produce certain responses from others. This realization is also accompanied by more vocalizations like gurgling, babbling, cooing, and other noises. These are all ways that your baby is starting to express themself.3
6 Months – Undiscriminating Smile: At this point, your baby is all smiles all the time! Just kidding. They will certainly have their fair share of other emotions, but most parents start to see a difference in their baby’s ability to smile at a lot more things (and people).3
9 Months – Selective Smile: Around nine months of age, your baby will start to be able to distinguish their parents as special and different from other people. They gain an understanding of the existence of strangers. The ability to distinguish different faces from a parent’s face is crucial to healthy development and survival. However, “stranger anxiety” can make your baby seem a lot shyer and more cautious than they were at six months old.3
12 Months – Sense of Humor: At around their first birthday, your baby’s sense of humor will begin to develop. They’ll laugh and laugh at things that surprise them or silly faces and noises. Even dropping something on the floor may make them belly laugh. Your baby will also be looking for a response when they laugh, so if you laugh with them, they may laugh even harder.3
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