Social referencing has been conceived as the process whereby, in the fourth quarter of their first year, human infants seek out and use information in the facial (but also vocal and/or gestural) emotional expressions of others (most often the mother) to cue/guide their responding in contexts of uncertainty or ambiguity (Campos & Stenberg, 1981; Klinnert, Campos, Sorce, Emde, & Svejda, 1983). Social referencing also has been characterized as infants' perception and use of other persons' interpretations of a situation to form their own understanding of that situation (Feinman, 1982; Feinman & Lewis, 1983). Up to now, the infant social referencing literature has devoted almost total emphasis to describing and delineating this phenomenon, and to emphasizing the feature of affective communication between mother and infant (Campos & Stenberg, 1981; Feinman, 1983, 1985; Gunnar & Stone, 1984; Hornik & Gunnar, 1988; Klinnert, Emde, Butterfield, & Campos, 1986; Walden & Ogan, 1988; Zarbatany & Lamb, 1985). To date, the main etiological theory in the literature has been preformationist, that infant social referencing involves prewired responses and perceptions, a "prewired communication process' (Campos, 1983).