•Babies in the first few weeks of life are said to be in this stage. During this stage the baby recognises and starts to form a bond with its carers. However, the baby’s behaviour towards non-human objects and humans is quite similar.•Babies show some preference for familiar adults, in that those individuals find it easier to calm them. Babies are also happier when in the presence of other humans.•During this stage, reciprocity and interactional synchrony play a role in establishing the infant’s relationship with others.