Abstract
Previous research has demonstrated that the level of performance achieved for a given workload level is affected not only on task demands and individual differences, but also by sequential effects of prior workload. The majority of this research has been done with vigilance-type tasks, wherein performance is an intermittent response to critical signals. Workload is then varied either by adjusting the signal rate or adding a secondary task. This study sought to demonstrate that workload can be assessed with Transcranial Doppler (TCD) in addition to performance and other physiological measures, and that workload transition results generalize to more complex tasks. TCD and electrocardiographic (ECG) data were collected while participants performed the Multi-Attribute Task Battery (MATB, Comstock & Arnegard, 1992). Two levels of workload were individually defined based on performance via a pretest calibration procedure; one level was relatively easy with a mean composite TLX score of 23 and the other relatively difficult with a mean composite TLX score of 63. These two levels were run in isolation and in transition runs that switched from one to the other halfway through. TCD and ECG revealed that both blood flow velocity and heart rate increased with increasing task difficulty, while the transition in task difficulty produced nonsignifcantly lower performance than runs of consistent difficulty. The physiological data provides evidence that additional physical resources are demanded and consumed in response to the change in task difficulty, while performance data collected to date has not revealed transition effects in the complex task.
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