 These episodes of joint engagement were predictive of later vocabulary and word learning, especially when the joint attention was focused on an object that the infant was initially attending to, such as when an infant picks up a ball, then the mother engages in a joint attention episode with the infant using the ball as the shared point of reference.At later ages, when initiating joint attention, the frequency that a child combines one word with a gesture (e.g., pointing to the plane and saying "plane") is associated with earlier onset of multi-word utterances, and more complex speech overall at 3.5 years old.Self-concept refers to the set of attributes, abilities, attitudes, and values that one identifies as defining who he or she is.