Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIED51 - AC/243(Panel-8)TR/7Volume 23.2 FITTS' LISTWhat the technique doesThe technique compares the capabilities of man and machine in terms of general task abilities, such as "data sensing,"and "reacting to unexpected events."Inputs to the techniqueA list with comparative characteristics of man andmachine was published by Fitts (1951) and has beendeveloped by others (e.g. NNAG, 1991). The systemfunctions must be expressed in terms which permit theidentification of one of the items in the categories ofman/machine capabilities contained in the list.Outputs of the techniqueThe technique produces lists of system functionsannotated by their allocation to man or machine.When to useIn the early stages of design, following a function analysis.Table 3.2: Original Fitts List (from Price, 1985; after Fitts, 1951)Humans appear to surpass present-day machines with respect to the following:1. Ability to detect small amounts of visual or acoustic energy2. Ability to perceive patterns of light or sound3. Ability to improvise and use flexible procedures4. Ability to store very large amounts of information for long periods and to recall relevant facts at theappropriate time5. Ability to reason inductively6. Ability to exercise judgmentPresent day machines appear to surpass humans with respect to the following:1. Ability to respond quickly to control signals. and to apply great force smoothly and precisely-2. Ability to perform repetitive, routine tasks3. Ability to store information briefly and then to erase it completely4. Ability to reason deductively, including computational ability5. Ability to handle complex operations, i.e. to do many different things at onceRelated techniquesThe technique is related to simple methods of analysing functions.Resources requiredThe technique can be applied using pencil and paper. It requires only the Fitts' List and a compatible list of systemfunctions.NATO UNCLASSIFIED-51 -