Gewirtz (1986) claimed that any positively reinforcing behaviour of the caregiver encourages development of attachment – not just the provision of food
Monotropy - A baby's attachment to one particular caregiver is unique to that person
Social releasers - Smiling, cooing, gurgling and grasping are social releasers - they elicit an emotional response from the caregiver
Critical period - The first 6 months are critical in forming these attachments. After that it is more difficult. No disruption should occur within the first 30 months (2.5 yrs)
Internal working model - A template for future relationships. This is the mechanism by which attachments are 'transmitted' from one generation to the next
He found that 14 of them showed affectionless psychopathy, and of these, 12 had experienced lengthy separations from their mothers before the age of two years - during the crucial 30 months
Crying: The differences in the amount of crying in various episodes suggests that it seems to be the mother's absence that the babies found most distressing, not just being left alone
Attachment is primarily determined by biological factors because it is universal
Attachment is the result of nature - it continues to exist even when the baby does not behave in an 'attached' way
Attachment behaviours are also influenced by nurture, the situation can influence behaviour such as when the stranger is present, the baby may show close proximity to the carer
Adopts a standardised procedure - all infants were placed in the same episodes
Collects quantitative data in the form of attachment behaviours observed from the structured coding scheme
The controlled observation means that the research could be argued to lack ecological validity as the mothers and children were not in their natural environment
Infants may have experienced distress during the episodes of the strange situation, however their mothers were there and able to comfort them if necessary