Infancy research has been a quickly expanding field in recent decades. Since the early 1970s, an increasing body of research demonstrated that the capacities of the newborn baby were far more advanced than previously assumed. New methodologies, such as eye tracking, motor movement tracking, heart rate measurements, EEG measurements, and the like, have been used in experimental settings. Furthermore, video observations have been used to follow, for example, mother-infant interaction, both in natural settings (Trevarthen & Hubley, 1978) and experimental settings, such as in the Strange Situation developed by Ainsworth to measure infant's attachment (Ainsworth, 1982).