As infants gain familiarity with repeated exposure to a visual stimulus, their interest wanes and they look away sooner. The decrease in an infant's resposniveness is called ...

Habituation

Explanation:

Habituation is the process of decrease in infant's responsiveness. It is true that as infants gain familiarity with repeated exposure to a visual stimulus, their interest wanes and they look away sooner. This occurs because we are familiar to the situation.

Once we are familiar with the situation, we do not react more compared to the previous time. It is the simplest form of learning that occurs in our everyday life. It allows people to tune out non-essential stimuli and focus on the things that really demand attention.