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The link between user’s functional state dynamic and usability of the program interface
In recent years the usability became a central issue for program interfaces design. The effects of functional state in usability testing were examined in an experiment. 26 male students of technical specialties (M=21 years) operated
two users interfaces (hierarchical menus). In addition to various performance measures (e.g. task completion time, task completion rate), several psychophysiological measures were taken (e.g. electrocardiogram, galvanic skin
response, electroencephalogram). The regression analysis showed the importance of the functional state dynamic for the construction of the model (R2=0,667, p<0,001) considering two significant determinants of users subjective
system usability evaluation - eeg alpha rhythm power and heart rate variability. Furthermore our finding revealed that functional state dynamic indirectly influence on usability through interface satisfaction. Differences in psychophysiological parameters point to the need to consider more strongly the factor functional state in usability research and practice.