This can lead a child to become closer to their mother, the only caregiver. The role of primary caregiver is assigned to the mother. The child is generally ambivalent when the caregiver returns. These therapies concentrate on changing the child rather than the caregiver. Educating and providing emotional support to the caregiver is important. Grandparents serving as their grandchildren's caregiver is particularly common in rural China. Working models help guide behavior by allowing children to anticipate and plan for caregiver responses. Kevin Clymo responded by evoking Dorothea the child and caregiver. Secure attachment is a healthy attachment between the infant and the caregiver. Anxious-avoidant is an insecure attachment between an infant and a caregiver. There are tests for measuring the amount of stress on a caregiver. This is characterized by the infant's indifference toward the caregiver. Each of these groups reflects a different kind of attachment relationship with the caregiver. This occurs without a specific benefit to the caregiver. Joseph J. Campos research focuses on facial expressions between the caregiver and infant.