Final answer:
Children with secure attachment typically show distress when separated from their caregivers and happiness when reunited, which can be observed from ages 12-18 months. Secure attachment indicates the caregiver's responsiveness and the child's preference for the parent over strangers.
Step-by-step explanation:
To determine if a child has formed a secure attachment to another person, we can look for specific behaviors as illustrated by developmental psychologist Mary Ainsworth's Strange Situation experiment. Typically, children display secure attachment when they show distress upon their caregiver's departure but seek comfort and exhibit happiness upon their return. According to Ainsworth's research, securely attached children often have caregivers who are sensitive and responsive to their needs, providing a secure base to explore the environment and look for in times of stress. On average, secure attachment can be observed in children between the ages of 12-18 months when they also begin to show behaviors like stranger anxiety, which coincides with cognitive developments like object permanence as per Jean Piaget's cognitive developmental theory.
It's important to note that other attachment styles identified through this research include avoidant, resistant, and disorganized attachment. Secure attachment is unique as it demonstrates the child's preference for their parent over strangers, the comfort found in the presence of the caregiver, and the ability to utilize the caregiver as a base for exploration. Building on the work of John Bowlby, Ainsworth's research in the field of developmental psychology has emphasized the importance of early attachment for social and emotional development.