Touch Perception

Touch stimuli cause changes in the skin that give us the sensations of pressure, warmth, and vibration. Touch is the earliest sensory system to develop in all species. When a human embryo is less than an inch long and less than two months old, the skin is already highly developed. When the palm is touched at two months gestation, the fingers grasp the palm. The fingers and thumb will close at three months when the palm is touched. The fetus can turn toward a tactile stimulus, much like a rooting reflex, and the fetus responds to electrical stimuli and puffs of air that are ...