formation of children's close relationships. Later criticisms of attachment theory relate to temperament, the complexity of social relationships, and the limitations of discrete patterns for classifications. Attachment theory has been significantly modified as a result of empirical research, but the concepts have become generally accepted. Attachment theory has formed the basis of new therapies and informed existing ones, and its concepts have been used in the formulation of social and childcare policies to support the early attachment relationships of children. Attachment Within attachment theory, attachment means an affectional bond or tie between an individual and an attachment figure (usually a caregiver). Such bonds may be reciprocal between two adults, but between a child and a caregiver, these bonds are based on the child's need for safety, security, and protection — which is most important in infancy and childhood. Attachment theory is not an exhaustive description of human relationships, nor is it synonymous with love and affection, although these may indicate that bonds exist. In child-to-adult relationships, the child's tie is called the "attachment" and the caregiver's reciprocal equivalent is referred to as the "care-giving bond". The theory proposes that children attach to carers instinctively, for the purpose of survival and, ultimately, genetic replication. The biological aim is survival and the psychological aim is security. The relationship that a child has with their attachment figure is especially important in threatening situations. Having access to a secure figure decreases fear in children when they are presented with threatening situations. Not only is having a decreased level of fear important for general mental stability, but it also implicates how children might react to threatening situations. The presence of a supportive attachment figure is especially important in a child's developmental years. Infants will form attachments to any consistent caregiver who is sensitive and responsive in social interactions with them. The quality of social engagement is more influential than the amount of time spent. The biological mother is the usual principal attachment figure, but the role can be taken by anyone who consistently behaves in a "mothering" way over a period of time. Within attachment theory, this means a set of behaviours that involves engaging in lively social interaction with the infant and responding readily to signals and approaches. Nothing in the theory suggests that fathers are not equally likely to become principal attachment figures if they provide most of the child care and related