Laparoscopy places significant demands on visual attention and requires extensive practice to become proficient. Scerbo et al. have developed a method of assessing mental workload with a secondary task that requires spatial abilities.1,2 The task is based on multiple resource theory, which states that “pools” of attentional resources are distinguished by: information processing stages, verbal/spatial codes, and visual/auditory modalities.3 When two tasks performed simultaneously require the same pool of resources, they can interfere with one another and increase mental workload. Thus, when a secondary task requiring the same attentional resources needed for laparoscopy is performed with a laparoscopic task, it can provide an index of mental workload. Our goal was to use a spatial secondary task to measure mental workload during the initial acquisition of basic laparoscopic skills on a simulator. Performance on two laparoscopic tasks differing in difficulty was measured across training sessions. We hypothesized that mental workload would initially be high (and more so on the difficult task) but would decline over sessions as trainees became more proficient as indexed by secondary task performance.
Fourteen surgical assistant students with no prior laparoscopic experience participated in this IRB approved, repeated measures study. They practiced cutting (high difficulty) and peg transfer (low difficulty) tasks from the Fundamentals of Laparoscopic Surgery for approximately 45 min over 11 sessions and were assessed with the secondary task at the end of each session. The secondary task presented observers with four balls in a simulated tunnel, superimposed at 50% transparency over the laparoscopic display. The balls were presented for 300 msec approximately every 4 sec. On half the presentations, one ball changed its position and participants responded to that change by pressing a foot pedal. They performed the secondary task by itself and in conjunction with the laparoscopic tasks.
All data were analyzed with a 2 Condition x 11 Session repeated measures ANOVA. There was a significant effect for laparoscopic tasks, F(1,11) = 15.72, p = .002, partial Ã†Å¾2 =.59. Completion times were faster for the peg (M = 102.57 sec, SE = 5.30) than the cutting task (M = 121.90 sec, SE = 5.08). Times declined significantly over sessions, F(10,110) = 38.88, p < .001, partial Ã†Å¾2 =.77, but leveled off by the sixth and second sessions for the peg and cutting tasks, respectively. There were significant effects for the secondary task scores, F(1,12) = 31.88, p = .000, partial Ã†Å¾2 =.73. The proportion of correct responses for cutting (M = .36, SE = .07) was lower than for pegs (M = .46, SE = .07), and scores on both tasks were lower than the secondary task performed by itself. Scores increased over sessions,F(10,120) = 3.11, p = .001, partial Ã†Å¾2 =.21; but only the difference between the first (M = .31, SE = .05) and eleventh session (M = .45, SE = .07) was significant.
The Results show that performance on the peg and cutting tasks reached a plateau midway through the training sessions. The findings for the spatial secondary task supported expectations. Workload was initially higher (lowers scores) and remained higher for the more difficult cutting task and although the scores increased over sessions for both tasks, the improvements were modest. These Results show that the mental workload experienced by novices practicing laparoscopic tasks may be quite high. They also support findings obtained by Stefanidis et al. on a suturing task who observed high levels of mental workload by novices who had met their training goals.2 Collectively, these findings show that the spatial secondary task provides an objective index of mental workload, offering a broader picture of laparoscopic skill acquisition.
1. Scerbo, M.W., Croll, M.M., Garcia, H.M., Stefanidis, D., Britt, R. C., & Davis, S. S. (2012). A spatial task for measuring laparoscopic mental workload. Simulation in Healthcare, 7, 558.
2. Stefanidis, D., Scerbo, M.W., Smith, W., Acker, C.E., & Montero, P.N. (2012). Simulator training to automaticity leads to improved skill transfer compared with traditional proficiency-based training: A randomized controlled trial. Annals of Surgery, 255, 30–37.
3. Wickens, C. D. (2002). Multiple resources and performance prediction. Theoretical Issues in Ergonomic Science, 3, 159–177.
Medical Cyberworlds, Inc. Gore, Bard honoraria for teaching.
© 2013 by Lippincott Williams & Wilkins, Inc.