1. MENTAL WORKLOAD ASSESSMENT

2. Learning objectives • Understand the difficulties in defining mental workload. • Give an account of why the discussion of mental work load is useful • Critically and comparatively evaluate the different ways of assessing mental workload. • Have a range of examples of the measurement of mental workload in different real world setting of your choice.

3. WHAT IS MENTAL WORKLOAD? • The mental stress and strain of being busy at work • Excessive ‘mental workload’ often leads to errors • Mental Workload’ is important in the operation of Safety critical systems

4. Workload as a construct • Is it something we can measure.Is it like mass or someone’s temperature • Is it an idea that can be used to summarise many other things ~ a short hand • Is it something that links different issues? • Is it a key idea in Orgnomics

5. Examples of ‘mental’ tasks • Vigilance • Problem recognition and diagnosis • Planning and action • Prioritisation • Remembering to do things • Rapid integration • Coping with the unexpected

6. Mental workload in real life • Not a new idea • Pilots • GPs • Design team • These examples show different facets of mental workload • What are the consequences of high mental workload in these situations

7. Workload as an organisational issue • Training • Development • Management style • Equipment • Task organisation

8. Defining mental workload • Not easy • A working definition might be ‘the real and perceived increase in task difficulty caused by any factors that impair decision-making planning and reasoning and other mental tasks concerned with the job in hand’. • Tautological • The importance of context

9. Generic measures of Mental workload • Generic measures are poor as they ignore context. • For example, same plane, same pilots, different routes. • Workload is highly context dependent

10. FACTORS THAT IMPACT UPON OPERATOR ‘MENTAL WORKLOAD’? • Skill levels • Operating rules and procedures • Operating conditions • Staffing levels • Task allocation • Organisational expectations

11. Task analysis Secondary tasks Physiological correlates Task performance over a busy time Subjective ratings Measuring mental workload over a busy time Measuring mental workload

12. Classic task analysis • A decompositional analysis of operators tasks • Advantages – anchored in context • Disadvantages – does not deal well with high levels of task.

13. Quasi computational Metrics • Attempt to make generic measures. • NASA TLX is one example • Poor validity in real world situations • Advantages – the process is enlightening even if the result is subjective and possibly misleading. • Disadvantages – they do away with context which is the main thing.

14. A note on the mental workload literature • Large and reef like (some of it is very pretty but much of it is dead!) • The approaches have various faults, but the d to do away with context. • Or a wish lists, sting the obvious and then failing to deal with a problem. • Review them critically

15. Illustrative Bibliography • Bainbridge, L (1978) Forgotten alternatives in skill and workload. Changes in cognitive processes with the development of skill, and the implications for mental workload.Ergonomics, 21, 169-185. Simultaneously published as: (1977) • Bainbridge, L, (1974) Problems in the assessment of mental load)The adaptation of cognitive processes to task demands and mental capacity: some reasons for the lack of correlation between objective and subjective mental workload.Le Travail Humain, 37 (2), 279-302. • Bainbridge, L (1989) Development of skill, reduction of workload. ()Described by title.In Bainbridge, L. and Ruiz Quintanilla, S.A. (eds.), Developing Skills with Information Technology, Wiley, pp. 87-116. • Moray, N. Johansson, J. Pew, R. Rasmussen, J. Sanders. A.F., & Wickens, C.D. (1979) Mental Workload, It’s theory and measurement. New York. Plenum Press. • O’Donnell. R.D, & Eggemeier, F.T., (1986) Workload Assessment methodology, In Boff, K., Kaufman, L., &Thomas, J., (eds) Handbook of perception and Human Performance, Vol II (pp42-1 pp 42-49. new Your, Wiley. • Schvaneveldt, R.W., Gomez R.L, & Reid, G.B, Recent unpublished report from New Mexico and Arizona State Universities and Armstrong Laboratories, Wright Patterson AFB, http://interlinkinc.net/Roger/Papers/Workload.pdf • de Waard, D, (1996), The Measurement of Drivers' Mental Workload ISBN 90-6807-308-7 Paperback, 198 pages Published by the Traffic Research Centre (now Centre for Environmental and Traffic Psychology), University of Groningen. http://www.home.zon.be/waard2/mwl.htm

16. An important thing to rememberWhich comes first? • The definition? • The method of measurement?The technical problem? • The organisational problem? • And how do these last to things differ or are they really the same. • Are we interested in high work load only.

17. Driving a car. • When learning to drive. • Variation of familiar route while trying to have telephone conversation. • Digital versus analogue speedometer. • Car running badly in heavy traffic. • Driving van through icy mountain roads.