The response that children who are four months of age or less give to human touch and tickling is not the result of being ticklish. Children at this age in life do not perceive external causes of touch in any form but do experience the sensations of touch. Andrew Bremner of Goldsmiths at the University of London and colleagues are the first to describe the early development of sensory stimulation in the edition of the journal Current Biology.
The study relied on a common phenomenon in adults and children over six months of age. The majority of people cannot determine which foot has been touched when their legs are crossed. The same is true of being touched when a person’s hands are crossed. Infants that are four months old can tell what foot or hand has been touched 70 percent of the time even if their hands or feet are crossed while adults and children over six months of age usually fail to tell what hand or foot were touched 50 percent of the time.
Children that are four months of age perceive touch as a total body experience rather than a localized experience. The researchers consider that the lack of sensory stimulation prior to birth and the inability to distinguish the external world from the self are the major factors in the lack of localized tickling discrimination in infants. The concept was verified by the fact that people who are born blind can localize touch 100 percent of the time even if their hands or legs are crossed while people who become blind after birth cannot.
