At what age do infants start to exhibit stranger anxiety according to Bowlby's phases of attachment?

Stranger anxiety typically emerges around the age of 9 to 12 months, according to Bowlby's phases of attachment. This phase is observed as infants begin to develop a clear attachment to their primary caregivers. It signifies their growing ability to recognize familiar faces and differentiate between known individuals and strangers. As infants move through these developmental milestones, they exhibit anxiety or caution around unfamiliar people, which is a normal part of their social and emotional development. This anxiety is a reflection of their increased attachment security with caregivers and suggests that they are beginning to understand social relationships and the concept of trust.