At what age is it common for an infant to giggle and show vocal excitement or displeasure?

Infants typically begin to giggle and express vocal excitement or displeasure around the age of 4 to 6 months. This stage of development is critical as it marks significant growth in their social and communicative skills. At this age, babies become more interactive and responsive to their environment, often displaying emotions through laughter and vocal sounds. This vocalization is not just a reaction but a form of communication, indicating their engagement and enjoyment or discomfort with the stimuli around them.

As infants reach this milestone, they also start to explore sounds and experiment with different pitches and tones, contributing to their social bonding with caregivers and other individuals. It’s a joyful phase in their emotional development that lays the foundation for later interactive behaviors. The timing around 4 to 6 months is consistent with developmental psychology insights regarding the emergence of social laughing, which typically occurs as they become more aware of social interactions and responsive to stimuli.