Secondary Task Measurement of Workload as a Function of Simulated Vehicle Dynamics and Driving Conditions

Abstract

A driving simulator with a six-degree of freedom computer-generated display, a four degree of freedom physical motion system, and a three-channel sound system was used to determine the sensitivity of a secondary task to vehicle handling parameters and various driving conditions. Six subjects drove a simulated vehicle with normal automobile handling and another six drove with degraded handling (slow response). Steering ratio and disturbance level were adjusted within each set of six subjects. A secondary task consisting of reading random digits aloud from a single-digit dashboard display was used to assess workload. Using a technique similar to that of Knowles (1963) and McDonald (1973), it was found that workload increased significantly as disturbance level increased. Furthermore, workload increased significantly with degraded vehicle handling. In contrast, increasing steering ratio did not produce a significant change in workload. These results indicate that the secondary task method can be used to assess the major effects of simulated vehicle handling on driver workload. The secondary task used is directly transferable to test vehicles, and it allows the assessment of large changes in primary task difficulty even though direct primary task measurement may not be feasible or economical. Problems remain, however, in designing more sensitive secondary-task measures.

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References

Bahrick

H. P.

Noble

Fitts

P.M.

Extra-task performance as a measure of learning a primary task. Journal of Experimental Psychology, 1954, 48, 298–302.

Brown

I. D.

The measurement of perceptual load and reserve capacity. Transactions of the Association of Industrial Medical Officers, 1964, 14, 44–49.

Brown

I. D.

A comparison of two subsidiary tasks used to measure fatigue in car drivers. Ergonomics, 1965, 8, 467–473.

Brown

I. D.

Subjective and objective comparisons of successful and unsuccessful trainee drivers. Ergonomics, 1966, 9, 49–56.

Brown

I. D.

Poulton

E. C.

Measuring the spare “mental capacity” of car drivers by a subsidiary task. Ergonomics, 1961, 4, 35–40.

Bundorf

R. T.

Driver-vehicle control performance. Proceedings of the Automotive Safety Seminar, sponsored by Automotive Safety Engineering, Environmental Activities Staff, General Motors Corporation, June 20–21, 1973, 51–61.

Craik

K. H. W.

Theory of the human operator in control systems. British Journal of Psychology, 1948, 38, 142.

Hagen

R. E.

Sex differences in driving performance. Human Factors, 1975, 17, 165–171.

Hick

W. E.

Reaction time for the amendment of a response. Quarterly Journal of Experimental Psychology, 1949, 1, 175.

10.

Hoffman

E. R.

Joubert

P. N.

The effect of changes in some vehicle handling variables on driver steering performance. Human Factors, 1966, 8, 245–263.

11.

Kelley

C. R.

Wargo

M. J.

Cross-adaptive operator loading tasks. Human Factors, 1967, 9, 395–404.

12.

Knowles

W. B.

Operator loading tasks. Human Factors, 1963, 5, 155–161.

13.

Leonard

J. J.

Wierwille

W. W.

Human performance validation of simulators: Theory and experimental verification. Proceedings of the Human Factors Society annual meeting, October, 1975, 446–456.

14.

McDonald

L. B.

A model for predicting driver workload in the freeway environment: A feasibility study. Unpublished doctoral dissertation, Texas A & M University, 1973.

15.

McLane

R. C.

Wierwille

W. W.

The influence of motion and audio cues on driver performance in an automobile simulator. Human Factors, 1975, 17, 488–501.

16.

Michon

J. A.

Tapping regularity as a measure of perceptual motor load. Ergonomics, 1966, 9, 401–412.

17.

Repa

B. S.

Wierwille

W. W.

Driver performance in controlling a driving simulator with varying vehicle response characteristics. (SAE Paper No. 760779) Presented at SAE National Automobile Engineering and Manufacturing Meeting, Detroit, October, 1976. (See also GM Research Laboratory Report No. GMR-2205, July 27, 1976.).

18.

Rolfe

J. M.

The secondary task as a measure of mental load. In Singleton

W. T.

(ed.) Measurement of man at work. New York: Van Nostrand-Reinhold, 1971, 135–148.

19.

Senders

J. W.

Kristofferson

A. B.

Levison

W. H.

Dietrich

C. W.

Ward

J. L.

The attentional demand of automobile driving. Highway Research Record, 1967, 195, 15–33.

20.

Welford

A. T.

The “psychological refractory period” and the timing of high speed performance—A review and a theory. British Journal of Psychology, 1952, 43, 2–19.

21.

Wierwille

W. W.

A part-task driving simulator for teaching and research. Computers in Education Transactions of ASEE, 1973, 5, 193–203.

22.

Wierwille

W. W.

Driving simulator design for realistic handling. Proceedings of the Third International Conference on Vehicle System Dynamics, Amsterdam: Swets and Zeitlinger, 1975, 186–199.

23.

Zeitlin

L. R.

Finkelman

J. M.

Research Note: Subsidiary task techniques of digit generation and digit recall as indirect measures of operator loading. Human Factors, 1975, 17, 218–220.