Impact of experience on the sensitivity, acceptability, and intrusive of two subjective mental workload techniques: The NASA TLX and workload profile.

BACKGROUND: Today's work environments have high cognitive demands, and mental workload is one of the main causes of work stress, human errors, and accidents. While several mental workload studies have compared the mental workload perceived by groups of experienced participants to that perceived by novice groups, no comparisons have been made between the same individuals performing the same tasks at different times. OBJECTIVE: This work aims to compare NASA Task Load Index (NASA-TLX) to Workload Profile (WP) in terms of their sensitivity. The comparison considers the impact of experience and task differentiation in the same individual once a degree of experience has been developed in the execution of the same tasks. It also considers the acceptability and intrusivity of the techniques. METHODS: The sample consisted of 30 participants who performed four tasks in two sessions. The first session was performed when participants had no experience; the second session was performed after a time of practice. Mental workload was assessed after each session. Statistical methods were used to compare the results. RESULTS: The NASA-TLX proved to be more sensitive to experience, while the WP showed greater sensitivity to task differentiation. In addition, while both techniques featured a similar degree of intrusivity, the NASA-TLX received greater acceptability. CONCLUSION: The acceptability of WP is low due to the high complexity of its dimensions and clarifying explanations of these may be necessary to increase acceptability. Future research proposals should be expanded to consider mental workload when designing work environments in current manufacturing environments.

Design and validation of a questionnaire in Spanish language for software usability evaluation.

BACKGROUND: Usability is an essential characteristic of software development, which needs to be evaluated mainly through questionnaires. However, the questionnaires available in Spanish are limited and not available for most software's developers and users. OBJECTIVES: This work aimed to design and validate a new questionnaire to evaluate software usability, considering the characteristics of efficiency, effectiveness, and satisfaction as defined by the International Standards Organization. METHODS: The Software Usability Assessment Questionnaire or SUAQ in Spanish language was designed and validated using Kendall's coefficient, Cronbach's Alpha, Factorial Analysis and Scree test. RESULTS: The questionnaire's validation was carried out by five experts through an evaluation of the clarity, coherence, and relevance of the proposed items. Once the questionnaire was administered to 95 participants, an overall reliability value of Cronbach's alpha of 0.839 was obtained. The factorial analysis is viable since a value of 0.757 was found in the Kaiser-Meyer-Olkin (KMO) test, and a significant value was obtained in Bartlett's sphericity test. CONCLUSIONS: The proposed questionnaire proved to be valid and reliable, and therefore, suitable to evaluate software usability in the Spanish language.