The still face experiment is a procedure developed by Edward Tronick in 1978, where a mother faces her baby, and is asked to hold a ‘still face’, in which she does not react to the baby’s behaviours. The reactions of the baby are then observed. In general, the baby will become agitated by failed attempts to evoke a reaction in the mother. Babies of depressed mothers have been shown to exhibit a lesser reaction, and baby boys have been found to have more difficulty than girls in maintaining affective regulation during the procedure.
Robinson, M. (2011). Understanding Behaviour and Development in Early Childhood: A Guide to Theory and Practice. (p-48). London: Routledge.