What behavior suggests that an infant is showing habituation?

Habituation is a fundamental form of learning observed in infants characterized by a decrease in response to a stimulus after repeated exposure to it. When an infant displays habituation, they initially respond with interest or attention to a new stimulus, such as a toy. However, with successive presentations of the same stimulus, their attention diminishes, indicating that they have become accustomed to it.

The behavior of ignoring a new toy after repeated exposure exemplifies habituation, as it highlights the infant's diminished response to something that was once novel and exciting. This process allows infants to efficiently process their environment by focusing on novel stimuli that may warrant further exploration or attention, rather than becoming overstimulated by familiar items they have already encountered.

The other options reflect different types of behaviors. For instance, staring at a new toy for a short period shows initial interest but does not demonstrate reduced responsiveness over time. Grabbing a new toy immediately indicates curiosity and an active response rather than habituation. Smiling at familiar objects could indicate recognition and comfort but does not specifically illustrate the key concept of habituation where the response declines with repeated exposure. Thus, the behavior of ignoring the toy is a clear sign of habituation.