Bowlby suggests that there is a critical period for developing at attachment (about 0 - 2.5 years).
Bowlby claimed that if an attachment did not happen in the critical period, then it may well not happen at all.
Bowlby suggested that social releasers, which are innate cues that babies give to caregivers, activate interactions during the first few months.
Bowlby recognised that attachment was a reciprocal process.
Bowlby later extended the critical period to become a sensitive period up to age 5 or 6.
Bowlby argued that a break in the bond during the critical period would have long-term detrimental effects on the child.
Bowlby argued that a break in the bond during the critical period could lead to irreversible psychological damage for the child.
Bowlby claimed that a secure bond must develop in the first 2.5 years of a child's life. If not, it will result in long-lasting negative social consequences.