Psychometric Properties of NASA-TLX and Index of Cognitive Activity as Measures of Cognitive Workload in Older Adults.

Hannes Devos,William M Brooks,Jeffrey M Burns,Kathleen Gustafson,Pedram Ahmadnezhad,Ke Liao,Jonathan D Mahnken

doi:10.3390/brainsci10120994

Abstract

Cognitive workload is increasingly recognized as an important determinant of performance in cognitive tests and daily life activities. Cognitive workload is a measure of physical and mental effort allocation to a task, which can be determined through self-report or physiological measures. However, the reliability and validity of these measures have not been established in older adults with a wide range of cognitive ability. The aim of this study was to establish the test–retest reliability of the National Aeronautics and Space Administration Task Load Index (NASA-TLX) and Index of Cognitive Activity (ICA), extracted from pupillary size. The convergent validity of these measures against event-related potentials (ERPs) was also investigated. A total of 38 individuals with scores on the Montreal Cognitive Assessment ranging between 17 and 30 completed a working memory test (n-back) with three levels of difficulty at baseline and at a two-week follow-up. The intraclass correlation coefficients (ICC) values of the NASA-TLX ranged between 0.71 and 0.81, demonstrating good to excellent reliability. The mean ICA scores showed fair to good reliability, with ICCs ranging between 0.56 and 0.73. The mean ICA and NASA-TLX scores showed significant and moderate correlations (Pearson’s r ranging between 0.30 and 0.33) with the third positive peak of the ERP at the midline channels. We conclude that ICA and NASA-TLX are reliable measures of cognitive workload in older adults. Further research is needed in dissecting the subjective and objective constructs of cognitive workload.

Highlights

Despite its incredible power and flexibility, there are limits to the brain’s capabilities
Our results showed that pupillary response, transformed to an Index of Cognitive Activity (ICA), provides fair to good test–retest reliability as a measure of real-time cognitive workload in older adults with and without cognitive impairments
Our current results show that the NASA-TLX and ICA are reliable in older adults with and without cognitive impairment

Summary

Introduction

Despite its incredible power and flexibility, there are limits to the brain’s capabilities. Cognitive workload is the combined physical and mental effort put forth by an individual in response to the cognitive demand and time constraints of the task. Cognitive workload may have properties that offer relevant information beyond that provided by standard performance measures such as accuracy or response times of a task. With fewer resources available to attend to the task, older adults may show greater workload on a task compared to younger individuals [3]. This increased cognitive workload may reflect inefficient or compensatory use of neural resources to cope with the demand of the task. Some studies have suggested that this increased cognitive workload may serve as a predictor of cognitive decline [4]

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