Depending upon their ability to direct the eye from one point to another, Zettl (1973, p 140) recognizes three types of vectors: (a) graphic vectors are created by stationary visual elements such as buildings, telephone poles, etc., arranged so that they lead the eye into a particular direction: (b) index vectors are defined as the directional forces created by an object which points unquestionably towards a specific direction such as a anger pointing,
a sign, etc.; (c) motion vectors are created by someone or something actually moving in a particulat direction such as a person walking, a car moving, a skier coming downtthe slopes, etc.