Final answer:
The childhood attachment style where the child is unconcerned about the parent's presence or absence and does not seek comfort from them upon return is avoidant attachment.
Step-by-step explanation:
The type of childhood attachment where a child explores comfortably, shows no distress when a parent leaves, and does not seek out the parent upon their return is indicative of an avoidant attachment style. Children with avoidant attachment are unresponsive to the parent, they do not use the parent as a secure base from which to explore, and they do not display significant emotion when the parent departs or returns. This pattern of behavior might be connected to having caregivers who are insensitive and inattentive to the child's needs, according to Ainsworth's research.