Research on cognitive load evaluation with subjective method in manual assembly

Subjective scales have different kinds of applicability in diverse fields. This study intends to implement a quantitative approach to determine the applicability of subjective scales in manual assembly work and evaluate the cognitive load of assembly workers. A multi-scale research paradigm based on subjective evaluation method is proposed. Three typical task stages are extracted from the process of assembly work. The National Aeronautics and Space Administration Task Load Index (NASA-TLX) scale, PAAS scale and Workload Profile Index Ratings (WP) scale are selected for the design of 3 ×3 multi-factor mixed experiment. The power spectrum density (PSD) characteristics of electroencephalogram (EEG) are utilized to identify the difficulty levels of the three task stages. The relevant indicators of scale applicability are assessed. The results show that in terms of sensitivity, NASA-TLX scale reaches the highest sensitivity (F =999. 137, P =0 <0. 05). In terms of validity, NASA-TLX scale possesses the best concurrent validity (P =0. 0255 <0. 05). In terms of diagnosticity, NASA-TLX scale based on 6 dimensions takes on the best diagnostic performance. In terms of subject acceptability, WP scale performs the worst. According to the analytic hierarchy process (AHP) model, the applicability scores of NASA-TLX scale, PAAS scale and WP scale are determined as 3, 2. 55 and 1. 6714, respectively. Therefore, NASA-TLX scale is regarded as the most suitable subjective evaluation questionnaire for assembly workers, which is also an effective quantitative evaluation method for the cognitive load of assembly workers. © 2023 Inst. of Scientific and Technical Information of China. All rights reserved.