"Blind or partially sighted people experience the world through what is called haptic perception," said Ms Chetz Colwell, a computer specialist in the psychology department at the University of Hertfordshire, southern England. "This is a combination of tactile perception through the skin, as in the fingertips, and kinaesthetic perception, in which we are aware of the position and mass of an object in relation to the movement and disposition of the muscles and limbs interacting with it."