Define the concept of attachment and summarise the patterns of attachment seen in infants.

Attachment refers to the close, emotional bonds of affection that develop between infants and their caregivers. Attachment is generally observed through observation of separation anxiety, or emotional distress seen in many infants when they are separated from people with whom they have formed an attachment.
Mary Ainsworth, in the 1970s, developed a research paradigm to study attachment using separation anxiety as a measure. She found that most infants have a secure attachment, playing and exploring comfortably when mom is present, becoming visibly upset when she leaves, and calming quickly upon her return.
Some babies, however, show anxiety even when mom is near and protest excessively when she leaves, but are not particularly comforted when she returns. Ainsworth labelled this pattern anxious-ambivalent attachment. Finally, some babies sought little contact with their mothers and were not distressed when she left, a pattern Ainsworth labeled avoidant attachment.