an infant/baby to that of a toddler. Children need more sleep than adults—up to 18 hours for newborn babies, with a declining rate as the child ages. Until babies learn to walk, they are carried in the arms, held in slings or baby carriers, or transported in baby carriages or strollers. Most industrialized countries have laws requiring child safety seats for babies in motor vehicles. Common care issues Baby colic Bassinet/crib Cradle cap Day care Diaper rash Infant massage Immunization Pacifier Paternal bond Swaddling Teething Benefits of touch Experiments have been done with infants up to four months of age using both positive touch (stroking or cuddling) and negative touch (poking, pinching, or tickling). The infants who received the positive touch cried less often and vocalized and smiled more than the infants who were touched negatively. Infants who were the recipients of negative touch have also been linked with emotional and behavioral problems later in life. A lower amount of physical violence in adults has been discovered in cultures with greater levels of positive physical touching. Language development Caregivers of an infant are advised to pick up on the infant's facial expressions and mirror them. Reproducing and empathizing with their facial expressions enables infants to experience effectiveness and to recognize their own actions more easily (see mirror neurons). Exaggeratedly reproduced facial expressions and gestures are recommended, as they are clearer forms of expression. The baby's babbling should also be picked up and repeated. By imitating each other's sounds the first simple dialogues are initiated. Accentuated pronunciation and melodic intonation make it easier to recognize individual words in a sentence. However, it is not advisable to use simplified "baby talk" (e.g. "Did you 'ouch'?" instead of, "Did you hurt yourself?"). Even if parents cannot yet understand infants' babbling, a timely response by parents to babbling leads to faster language acquisition. This was confirmed by researchers who first studied mothers' behavior towards 8-month-old infants and later tested the infants' vocabulary when they were 15 months old. A first important development of infants is the discovery that they can influence their parents through babbling (development of intentional communication). Parents can encourage this by engaging with their infants in babbling. This in turn promotes further language development, as infants then turn to their parents more often. Previous studies have shown that the infant's speech is encouraged when parents, for example, smile in the infant's