Attachment is an emotional bond between an infant and caregiver that ensures the infant's survival. Mary Ainsworth's "Strange Situation" experiment identified patterns of attachment including secure, avoidant, ambivalent/resistant, and disorganized/disoriented. Factors like parental responsiveness and infant temperament influence attachment. Lack of attachment due to deprivation can harm development, as seen in studies of institutionalized children. Child abuse and neglect are prevalent issues with serious psychological effects. Autism spectrum disorders involve social and behavioral impairments. Daycare can have positive effects but small differences were found compared to home care. Emotional development in infants involves recognizing facial expressions and developing emotions.