Table 3.

Means for high- and low-expressivity newborns ^a (Field, 1982).

	Expressivity of Infant
Measures *	Low	High
Threshold
Pinpricks to response (#)	1.2	1.9
Expressivity
Accuracy of observers' guesses (%)
Happy (mouth widensed)	5.0	14.0
Sad (lip protrusion)	8.0	22.0
Surprise (mouth open)	20.0	44.0
Physiological responsivity
Heart rate variability (beats per minute)	23.0	32.0
Habituation
Trials to criterion	7.0	11.0
Looking time (seconds)	10.0	16.0

^*All means significantly different at p< .05