social interaction. A secure attachment with to a father who is a "secondary attachment figure" may also a counter the possible negative affects of an unsatisfactory attachment to a mother who is the primary attachment figure. Some infants direct attachment behaviour (proximity seeking) towards more than one attachment figure almost as soon as they start to show discrimination between caregivers; most come to do so during their second year. These figures are arranged hierarchically, with the principal attachment figure at the top. The set-goal of the attachment behavioural system is to maintain a bond with an accessible and available attachment figure. "Alarm" is the term used for activation of the attachment behavioural system caused by fear of danger. "Anxiety" is the anticipation or fear of being cut off from the attachment figure. If the figure is unavailable or unresponsive, separation distress occurs. In infants, physical separation can cause anxiety and anger, followed by sadness and despair. By age three or four, physical separation is no longer such a threat to the child's bond with the attachment figure. Threats to security in older children and adults arise from prolonged absence, breakdowns in communication, emotional unavailability or signs of rejection or abandonment. Behaviours The attachment behavioural system serves to achieve or maintain proximity to the attachment figure. Pre-attachment behaviours occur in the first six months of life. During the first phase (the first eight weeks), infants smile, babble, and cry to attract the attention of potential caregivers. Although infants of this age learn to discriminate between caregivers, these behaviours are directed at anyone in the vicinity. During the second phase (two to six months), the infant discriminates between familiar and unfamiliar adults, becoming more responsive toward the caregiver; following and clinging are added to the range of behaviours. The infant's behaviour toward the caregiver becomes organized on a goal-directed basis to achieve the conditions that make it feel secure. By the end of the first year, the infant is able to display a range of attachment behaviours designed to maintain proximity. These manifest as protesting the caregiver's departure, greeting the caregiver's return, clinging when frightened, and following when able. With the development of locomotion, the infant begins to use the caregiver or caregivers as a "safe base" from which to explore. Infant exploration is greater when the caregiver is present because the infant's attachment system is relaxed and it is free to