What was Meltzoff and Moore's (1977) procedure in investigating reciprocity in 2-3 week old infants?
1. An adult displayed one of three facial expressions or one of three gestures.
2. The baby's response was filmed and labelled by independent observers (who had no knowledge of the adults expressions and gestures).
3. Observers noted all instances of infant tongue protrusions and head movements using 4 categories: mouth opening, termination of mouth opening, tongue protrusion, termination of tongue protrusion.