In Evans and Porters study mothers and babies were invited into the laboratory on 3 occasions
At 6 , 9, and 12 months mother and baby pairs were provided with toys in an observation room and were instructed to play as normal for 15 mins. They were videoed and the extent of reciprocitty and degree of interactional synchrony were assessed
At 12 months, the quality of mother-infant attachment was assessed using the strange situation. Babies who were securely attached were those who had the most reciprocial interactions and the most interactional synchrony.