reflex smiling

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July 13, 2026

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Reflex smiling in newborns is an involuntary response that occurs without any external stimulus or reference to other people. This type of smiling is distinct from social smiling, which develops later as infants begin to respond to human faces and voices.1

Newborn infants display a range of inherited reflexes essential for survival, such as sucking and blinking. Reflex smiling is one of these early, automatic responses. By around two months of age, infants begin to smile in response to sounds, and by three to four months, they smile at the sight of a human face, marking the development of social smiling. This transition signifies the beginning of an infant's emotional engagement with others.12

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human behaviour
The newborn infant
…weeks constitute what is called reflex smiling and usually occur without reference to any external source or stimulus, including other people. By two months, however, infants smile most readily in response to the sound of human voices, and by the third or fourth month they smile easily at the sight…
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…weeks constitute what is called reflex smiling and usually occur without reference to any external source or stimulus, including other people. By two months, however, infants smile most readily in response to the sound of human voices, and by the third or fourth month they smile easily at the sight…
Read More