title: Workload assessment of surgeons: correlation between NASA TLX and blinks.
abstract: BACKGROUND
  Blinks are known as an indicator of visual attention and mental stress. In this study, surgeons' mental workload was evaluated utilizing a paper assessment instrument (National Aeronautics and Space Administration Task Load Index, NASA TLX) and by examining their eye blinks. Correlation between these two assessments was reported.
  
  
  METHODS
  Surgeons' eye motions were video-recorded using a head-mounted eye-tracker while the surgeons performed a laparoscopic procedure on a virtual reality trainer. Blink frequency and duration were computed using computer vision technology. The level of workload experienced during the procedure was reported by surgeons using the NASA TLX.
  
  
  RESULTS
  A total of 42 valid videos were recorded from 23 surgeons. After blinks were computed, videos were divided into two groups based on the blink frequency: infrequent group (≤ 6 blinks/min) and frequent group (more than 6 blinks/min). Surgical performance (measured by task time and trajectories of tool tips) was not significantly different between these two groups, but NASA TLX scores were significantly different. Surgeons who blinked infrequently reported a higher level of frustration (46 vs. 34, P = 0.047) and higher overall level of workload (57 vs. 47, P = 0.045) than those who blinked more frequently. The correlation coefficients (Pearson test) between NASA TLX and the blink frequency and duration were -0.17 and 0.446.
  
  
  CONCLUSIONS
  Reduction of blink frequency and shorter blink duration matched the increasing level of mental workload reported by surgeons. The value of using eye-tracking technology for assessment of surgeon mental workload was shown.
authors.affiliation: Department of Surgery, 3-002F Li Ka Shing Centre for Health Research Innovation, University of Alberta, 8440-112 St. NW, Edmonton, AB, Canada. bin.zheng@ualberta.ca
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
authors.forename: Xianta
authors.initials: X
authors.lastname: Jiang
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Tien
authors.forename: Adam
authors.initials: A
authors.lastname: Meneghetti
authors.forename: O Neely M
authors.initials: ON
authors.lastname: Panton
authors.forename: M Stella
authors.initials: MS
authors.lastname: Atkins
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D001767:Blinking / Q000502:physiology*; D001955:British Columbia; D003198:Computer Simulation; D004724:Endoscopy / Q000193:education*; D013502:General Surgery / Q000193:education* / Q000458:organization & administration; D006801:Humans; D007396:Internship and Residency; D008875:Middle Aged; D017145:Models, Educational; D013315:Stress, Psychological / Q000175:diagnosis* / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D013647:Task Performance and Analysis; D016526:Workload