Date of Award

Winter 1987

Document Type


Degree Name

Doctor of Philosophy (PhD)




Industrial/Organizational Psychology

Committee Director

Glynn D. Coates

Committee Member

Raymond Kirby

Committee Member

Kelli F. Willshire

Committee Member

Frederick G. Freeman


The present study investigated the effects of the addition of automation on task workload. Utilizing a modified secondary task paradigm, the workload which was imposed by three different levels of automation, selected from the continuum of automation on each of two primary tasks, was assessed by comparing performance on a secondary task which remained unaided in all conditions. The levels of automation under investigation in the present study were manual, intermediate, and total aiding. The primary tasks selected for investigation were a sensory-decision making task and compensatory tracking task. A long-term memory task was chosen as the secondary task. It was hypothesized that as the amount of aiding increased on the primary task such that the amount of cognitive processing required by the individual also increased, there would be a corresponding decrease in the performance of the secondary task. This decrease was hypothesized since in the aided conditions the individual was responsible not only for verifying that the system was in performing the task satisfactorily, but was also ultimately responsible in all the conditions for performing the task manually if deemed necessary. Sixty subjects were randomly assigned to one of six conditions by factorially combining the three levels of aiding and two levels of task combinations. Each subject received three experimental sessions.

The hypothesis that the addition of cognitive workload in conditions where increasing amounts of aiding was introduced into a task situation was not borne out by the results of this study. Results of this study suggested that a significant reduction in workload can be obtained by totally automating a particular task but that there is no significant reduction in the amount of workload when aiding, which gives advice to the individual, is compared to the situation where the individual must perform the task without assistance. Additional human factors research needs with regards to the introduction of automation were also identified.


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