Table 1.

Descriptions of Behavioral Coding during Free Play Task

Variable	Coding Definition
Social Interest:	Demonstration of social interest in peer through response and initiation.
1:	Lack of acknowledgement/reciprocity; ignores initiations of peer.
4:	Passive interest; responds to peer and sometimes initiates interactions.
7:	Total engagement with peer; frequent initiations.
Activity Level:	Demonstration of social interest in peer through response and initiation.
1:	Stays in one place or engages in few, slow movements.
4:	Short and infrequent bursts of intense activity.
7:	Continuous quick and intense movement (e.g., running, jumping, skipping).
Positive Affect:	Demonstration of positive affect.
1:	Complete absence of positive affect.
4:	Some expressions of excitement (e.g., singing, smiling, clapping).
7:	Continuous expressions of intense joy (e.g., laughing, smiling, yelling).
Aggression:	Physical or verbal aggression toward peer.
1:	Complete absence of aggressive acts.
4:	Harsh language directed at peer or forceful attempt to get toy.
7:	Frequent displays of aggression (e.g., name-calling, hitting, kicking, biting).

Note. Listed above are three anchors of the 7-point Likert scale for each variable. Lower scores indicated lower frequencies and intensities of the behavior, and higher scores indicated more frequent and intense displays of the behavior.