Document 5L3DVB1xMBXLX8xMEYrxeK0JV

COMMON TO NEARLY EVERY PERSON Handles used for controlling liquids are expected to turn clockwise for off and counter clockwise for on Knobs on electrical equipment are expected to turn clockwise for on, to increase current, and counter-clockwise for off or to decrease current (Note this is opposite to the stereotype for liquid) Toggle switches are expected to turn "on" when flipped up, "off" when flipped down Certain colors are associated with traffic, operation of vehicles, and safety For control of vehicles m which the operator is riding, the operator expects a control motion to the nght or clockwise to result in a similar motion of his vehicle, and vice versa Sky-earth impressions carry over into colors and shadings Light shades and bluish colors are related to the sky or up, whereas dark shades and greenish or brownish colors are related to the ground or down Things which are further away are expected to look smaller Coolness is associated with blue and blue-green colors, warmth with yellows and reds Very loud sounds or sounds repeated m rapid succession, and visual displays that move rapidly or are very bright, imply urgency and excitement Very large objects or dark objects imply heaviness Small objects or light-colored objects appear light m weight Large, heavy objects are expected to be at the bottom Small, light objects are expected at the top People expect normal speech sounds to be m front of them and approximately head height Seat heights are expected to be at a certain level when a person sits down Source Woodson and Conover, Human Engineering Guide for Equipment Design more relative than absolute judgements Function 3--Man as Controller The third function man serves in the manmachine system is that of controller Just as principles exist for designing displays for man to use more readily, so, too, can controls be designed to eliminate error The control function in the man-machine system can be considered as the response to a given stimulus For many situations, a generalized response is given Most Americans, for example, ex pect a light switch to be turned on by flipping the switch "up" and off by a "down" move ment A clockwise motion generally refers to an increase Such responses are called "population stereotypes," a behavioral response common 115