Essentials in Human Factors

We live in an ever-changing world. We receive new information daily and adjust our lives accordingly. Every day is not the same as the day before! Much of the information our senses receive is based on visual displays indicating quantity, quality, or other appraisal of some situation. Visual displays encompass dials, graphs, print material, computer screens, and other mechanical devices that translate complicated information into symbols, numbers, rates, trends, weights, or length in order for our brain to make judgments about information so depicted.

In quantitative displays, some quantity is converted to a number or other symbol. For example, a tire gauge denotes the pressure of air in the tire. That information is converted to a “number” and displayed on various types of gauges.  In qualitative displays, approximate values, trends, rate of change, or change in direction are used to provide the operator with valuable information (Sanders and McCormick, 1993). The speedometer on your car is a good example. A “check reading” determines if some variable is within “normal” or “abnormal” parameters. The “situation awareness” task is one of prediction. Where will aircraft viewed on a radarscope be in 5, 10, 15 minutes?

In designing displays one has to be cognizant of: 1) the need for the operator to acquire information, and 2) what information is necessary.  Remember, the central purpose of information processing is to reduce uncertainty.  The ability to translate complicated information to aid in decision-making, and to reduce needed information to one number or symbol, requires great thought planning.  Deciding what information, reduced to what number or symbol, displayed in what form to the operator, requires thoughtful consideration.

In terms of quantitative displays or dials, there are three basic designs. Two are fixed designs.  In the first type, the background remains fixed and the pointer moves.  In the second type, the pointer is fixed and the background moves (Sanders and McCormick, 1993).  Both of these two types present analog displays.  The difference is more than subtle because one has to be cognizant of how each display provides information to the operator. In analog indictors, the reading of the numbers is analogous to the value represented.