Table 2.

Descriptions of variables.

Variable	Comparing episodes	Measurement unit	Description
Contentment	Audio sep Video sep	Seconds	The period of time that the child was content to be physically alone in the play-room. Timed from the parent leaving the play-room until the child showed distress for 10 s, or attempted to leave the room. The maximum score was 300 as the maximum duration of each separation was 300 s (i.e., 5 min)
Maximum contentment	Audio sep	Yes/no	Did the child remain content for the entire 300 s?
	Video sep
Play	Free-play Audio sep Video sep	%	The percentage of intervals that the child remained during which he/she played. Play was defined as handling or otherwise interacting with toys as well as dancing, making funny faces with the parent, admiring their block buildings, etc
Interaction	Free-play Audio sep Video sep	%	The percentage of intervals that the child remained during which he/she talked (verbally communicated to the best of the child’s ability) to the parent
Response ratio	Free-play Audio sep Video sep	%	The percentage of parent’s questions to which the child responded. Responses could be verbal, non-verbal, and/or action responses
Affect	Free-play Audio sep Video sep	Score 1–5	Mean affect across the intervals of each episode. Rated on a five point Likert scale from 1 = extreme negative emotion, to 5 = extreme positive emotion, with three the neutral rating