Parents of newborn children sometimes notice an unusual phenomenon. Normal babies rarely close their eyes, except of course when sleeping.

Considering the world of visual stimuli to which infants are suddenly exposed, frequent blinking might seem natural for an infant. But studies show that they blink spontaneously at a rate far below that of adults.

One study, published in The Annals of Neurology, measured spontaneous blinking in 269 children and 179 adults. They found that infants blink on average less than twice a minute, a rate that steadily increases up to age 14 or 15. Adults, on average, blink 10 to 15 times a minute.

One theory is that infants, whose ability to see is incomplete, work hard to soak in visual information.

Blinking serves primarily to coat the eyes with tears and remove any dirt or debris from the surface of the cornea. So another theory is that infants, perhaps because their eyes are better protected by smaller openings or because they sleep so much, may require less eye lubrication.

In any case, parents are not imagining it: babies do not blink very often.

ANAHAD O’CONNOR