The strange situation was devised by Mary Ainsworth in 1970 in order to investigate how attachments might vary between children. It is an example of a controlled observation and is in a novel environment to the child. Four categories of behaviour are measured and observed: (1) separation anxiety, (2) stranger anxiety, (3) the infant's willingness to explore and (4) reunion behaviour. The behaviour of the caregiver is also observed.
The ppt containing the big table describing the three attachment types is here. You really need to know the difference between type A and type C (type B is secure).
