After considering the time required for participants to acquire SA, each air-traffic situation was presented for approximately ten to twelve minutes before they filled out SART and NASA-TLX evaluation sheets.
Higher scores of SART combined values indicate higher SA, while higher mean workload scores in NASA-TLX indicate a higher workload.
Table 4 shows NASA-TLX score summary and ANOVA results of NASA-TLX components.
Table 5 shows the correlation results between NASA-TLX and SART components.
The regression results to predict SA through NASA-TLX components showed that the overall model was statistically significant with F (6, 275) = 35.
It was verified that SA and workload had an inverse relation and the correlation coefficients between SART and NASA-TLX components became higher when analyzed at or above moderate traffic levels.
Through the experiments conducted during the course of this study, some components of SART and NASA-TLX constructs were associated with each other.
In the NASA-TLX, TLX-MD is defined as the mental and perceptual effort (e.
Abbreviations: ADL = activity of daily living, DSS = Drive-Safe System, FEW = Functioning Everyday with a Wheelchair, NASA-TLX = National Aeronautics and Space Administration-Task Load Index, NCT = number of collisions per trial, NCT-I = NCT-Type I, NCT-II = NCT-Type II, NCT-III = NCT-Type III, NCT-T = NCT-total, SD = standard deviation, TCT = task completion time, TLX-E = NASA-TLX Effort, TLX-F = NASA TLX Frustration, TLX-MD = NASA-TLX Mental Demand, TLX-PD = NASA-TLX Physical Demand, TLX-TWL = NASA-TLX Total Workload, UR = ultrasonic rangefinders.
During Session 7, for example, the team completed the team ratio in 134 sec during the 4-sec component (Figure 5), the most challenging of the three components as evidenced by the performance metrics and the NASA-TLX
Some researchers have considered completion of the weights component of the NASA-TLX to be unnecessary, because the correlation between weighted and unweighted workload scores was found to be +0.
Abbreviations: DS = driving session, ISO = International Organization for Standardization, MMSE = Mini-Mental State Examination, NASA-TLX = National Aeronautics and Space Administration Task Load Index, PIADS = Psychosocial Impact of Assistive Devices Scale, PIDA = Power-Mobility Indoor Driving Assessment, QUEST = Quebec User Evaluation of Satisfaction with Assistive Technology.