MENTAL WORKLOAD ASSESSMENT

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.

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

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

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

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

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

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

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

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

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

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

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.

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

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, Simultaneously published as: (1977)Forgotten alternatives 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), Problems in the assessment of mental load 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 Development of skill, reduction of workload 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 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, de Waard, D, (1996), The Measurement of Drivers' Mental Workload ISBN Paperback, 198 pages Published by the Traffic Research Centre (now Centre for Environmental and Traffic Psychology), University of Groningen.

An important thing to remember Which 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.

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.