Touch is one of the five senses through which animals interpret the world around them. (The other senses are smell, taste, sight, and hearing.) While the organs of the other senses are located primarily in a single area (such as sight in the eyes and taste in the tongue), the sensation of touch can be experienced anywhere on the body, from the top of the head to the tips of the toes.
Without the sense of touch, animals would not be able to recognize pain, which would greatly decrease their chances for survival. Research also has shown that touch is an important factor in child development, persuasion, healing, and reducing anxiety and tension.
The sense of touch is based primarily in the outer layer of the skin called the epidermis. Nerve receptors in the epidermis respond to outside stimuli by sending impulses along nerves through the central nervous system to the brain. The brain, in turn, interprets these impulses as heat, cold, pain, or pressure.
Scientists have identified several types of touch receptors, or nerve endings. One type is associated mainly with light pressure (such as wind) and pain and occurs at the base of hairs throughout the body. Another is found in the fingertips and areas especially sensitive to touch, such as the tongue and the soles of the feet. A third type is found in deep tissues in the joints, reproductive organs, and milk glands and is extremely sensitive to pressure and rapid movement of the tissues. The skin also contains specific receptors for sensing heat and cold as well as intense pain.
Epidermis: The outer layer of skin.
Nerve receptor: Nerve endings or specialized cells that are in close contact with nerves.
Stimulus: Anything that causes a response.
These receptors also are found in greater numbers on different parts of the body. The back is the least sensitive to touch, while the lips, tongue, and fingertips are most sensitive. Most receptors for cold are found on the surface of the face while receptors for warmth usually lie deeper in the skin and are fewer in number. A light breeze on the arm or head is felt because there tend to be more sense receptors at the base of the hairs than anywhere else.
Numerous studies of humans and other animals have shown that touch greatly affects physical development and mental well being. Premature babies that receive regular messages gain weight more rapidly and develop faster mentally than those who do not receive the same attention. Touch also appears to be a factor in emotional stability. Difficult children often have a history of abuse and neglect. Touch provides reassurance to infants that they are loved and safe. In general, babies who are held and touched tend to be more alert and aware of their surroundings.
Touch continues to have a psychological impact throughout peoples' lives. Adults who are hospitalized or sick at home have less anxiety and tension headaches when they are regularly touched or caressed by caretakers or loved ones. Touch also has a healing power and has been shown to have the capacity to reduce rapid heartbeats and restore irregular heartbeats to normal rhythm.
Touch is a powerful persuasive force. Salespeople often use touch to establish a bond that can result in better sales. People also are more likely to respond positively to a request if it is accompanied by a slight touch on the arm or hand.
[ See also Perception ]