The Search motion starts when the eyes and/or hand start to seek the object needed and ends just as the object is located. The Gilbreths stated that in a search, "....the time and attention required...varies with the number of dimensions in which the search is performed." A one-dimensional search might be locating a piece of paper on a desktop. A two dimensional search might be finding a light switch on a wall and the three dimensional search would be locating a hanging pull-chain for a light or fan. The Gilbreths also recognized that contrasting colors, shapes or embossed symbols could reduce the search function. This science has been expanded by the modern study of Human Factors Engineering. However, the classic example of the Gilbreths reducing Search was by arranging tools and parts in a physical sequence of use through the Packet Principle