TY - JOUR TI - Effect of hypobaric hypoxia on subjective perception of mental workload measured with NASA Task Load Index AU - YS,Dahiya AU - KK,Tripathi AB - NASA Task Load Index (NASA TLX), employed for prototype and systems evaluation, is a multidimensional subjective workload index which provides an overall workload score based on a weighted average of ratings in six dimensions. Out of its six dimensions, three relate to demands imposed and the other three relate to interaction of the subject with the task. Hypoxia may affect many of these constituent dimensions. Present study examined the effect of hypobaric hypoxia on the subjective perception of mental workload measured using NASA TLX. The study examined the effect of short term exposure (15 min) to mild hypobaric hypoxia (10,000 ft) and moderate hypobaric hypoxia (15,000 ft) simulated in a hypobaric chamber on NASA TLX measured during engagement of 16 healthy male volunteers in a working memory task with two difficulty levels. Order of administration of the two task variants and three altitude conditions was counterbalanced. Statistical procedure involved a two way analysis of variance. Results showed that the ratings in all dimensions of NASA TLX (except frustration) exhibited significant effect of task difficulty. However, no significant effect of task difficulty was observed on weights. On the other hand, no significant effect of hypoxia was observed in ratings, weights and weighted workload in any of the dimensions of NASA TLX as well as overall weighted workload despite a fairly high internal consistency amongst the constituent dimensions of NASA TLX as discerned through Cronbach’s Alpha. In conclusion, NASA TLX scores did conform to objectively defined task difficulty and demands. Also, the scores provided some diagnostic information regarding the source of load in the task. Results support the contention that subjective verbal reports do constitute legitimate psychological data. Workload derived from subjective measures (such as NASA TLX) is not sensitive enough to be affected by small deficits in the working memory during short term exposure to mild to moderate hypoxia. VL - 53 T2 - Indian Journal of Aerospace Medicine JO - Indian Journal of Aerospace Medicine J2 - Indian Journal of Aerospace Medicine SN - 0970-6666 SN - 2582-5348 ER -