Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIED- 53 -- AC/243(Panel-8)TR/7Volume 2AdvantagesFitts' list is simple to use, and requires little training.In practice the list is a convenient framework forconsidering the allocation of functions. It aids peopleunfamiliar with human factors to think systematicallyabout the functions assigned to human operators.DisadvantagesThe approach is simplistic and uses qualitative terms only.In practice it is of limited help. The listed functions requireinterpretation to relate them to system functions. Thecapabilities of man and machine are not directlycomparable; they are complementary. The approach ignoresother aspects of the allocation trade-off, such as cost andsize/weight/support requirements (Fitts, 1962). In addition.the technique treats the operator's tasks as independentmodules, which can be allocated without interaction.Relative contribution of the techniqueThere is little evidence available; despite frequent references lo it in the literature, Fitts' list is lialeaused in practice.One user reports that the technique is "not bad," another that it is "useless."ApplicationsDespite the frequent references to Fitts' list in the human factors literature, it appears to be little used. It was used inhe concept development of an ASW helicopter, an air defence system, a shipboard nuclear weapons safety system.and for a major update of a destroyer.Quality assurance considerations'Me listed functions must be interpreted carefully to relate them to typical system tunctions.Relationship to system performance requirementsThe output of the technique cannot be related directly to sVstem performance: it requires additional analyses.References and Bibliography1. Fitts, P.M. (1951). Human engineering for an effective air navigation and traffic control system. WashingtonD.C.: National Research Council.2. Fitts, P.M. (1962). Functions of man in complex systems. Aerospace Engineering. January.3. Kantowitz, B.H. & Sorkin, R.D. (1987). Allocation of functions. In: G. Salvendy (Ed.), Handbook of humanfactors (pp. 335-369). New York: John Wiley & Sons.4. NNAG (1991). Guidelines for automation implementation. Brussels: NATO Naval Armaments Group,Information Exchange Group 6/Sub-Group 8.5. Price, H.E. (1985). The allocation of functions in systems. Human Factors, 27 (1) 33-45.6. US Deparnment of Defcnse (1987). Human engineering procedures guide. Washington D.C: DoD-HDBK-763.NATO UNCLASSIFIED- 53 -