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Examining the Forgetting Curve and how it affects surgical skills education
Friday, April 28th, 11:00 AM - 11:10 AM - Display A - Lower Lobby

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INTRODUCTION: The Learning Curve is a graphical representation of performance improving with experience [1]. The lesser known and often overlooked counterpart of the Learning Curve is the Forgetting Curve, a graphical representation of how knowledge exponentially decays over time [2-3]. Studies have shown that most information learned is lost within two hours [3]. This phenomenon has been modelled and reproduced numerous times in psychology literature, but has been largely ignored in medical and surgical literature [2,4].  Currently, surgical residencies contain blocks of time where trainees have little or no surgical skills exposure, such as clinic and research rotations. There is a common perception that technical skill decays/declines during these lapses in practice, but the actual pattern of such a degradation has not been studied. The objective of this study is to determine whether there is indeed a “Forgetting Curve” in surgical skills education.

METHODS: We performed a prospective study of four Gynecology residents who  rotated through Sunnybrook Health Sciences Centre for their Urogynecology rotation. The residents were evaluated on their performance during a vaginal hysterectomy (VH), which is an ideal surgical skill for the study as it is mostly learned and practiced by residents during their Urogynecology rotation. Each resident was marked by the staff physician or fellow using a pre-validated Objective Structured Assessment of Technical Skills (OSATS) Global Rating Scale (GRS) and Checklist during their first VH of the rotation. This score was used as a baseline. Every subsequent time a VH was performed by a resident and evaluated, we noted the time that had elapsed since the resident’s previous VH. The resident’s GRS and Checklist scores were then normalized in relation to their baseline score. The results were analyzed using a linear correlation coefficient, and hypothesis testing of the significance of the correlations was performed.

RESULTS:  The study participants performed a total of 19 VH procedures in addition to the baseline VH procedure. A moderate negative linear correlation was found between time since last VH and OSATS Checklist scores (r = -0.44, p < 0.05). There was a moderate negative linear correlation between time since last VH and OSATS GRS results (r = -0.49, p < 0.05). These results are shown in Figure 1. When analyzing the resident with the most VH procedures (n=12) on a separate curve, we found a strong negative linear correlation between time since last VH and Checklist scores (r = -0.70, p < 0.05) and a moderate negative linear correlation between time since last VH and GRS results (r = -0.47, p < 0.05), as seen in Figure 2.

CONCLUSION: We found a significant, negative linear correlation between the time since last performing a VH and OSATS scores. Although the sample size was small and based on four residents’ performance, this preliminary data supports the theory that the phenomenon of the Forgetting Curve applies to surgical training as well. It would be beneficial to further study this effect with more study participants and VH procedures, in order to corroborate the theory. Furthermore, in the future we would like to determine whether the level of mastery of the skill affects the rate of forgetting (the slope of the forgetting curve).


1.Hopper A, Jamison M, Lewis W. Learning curves in surgical practice. Postgrad Med J. 2007;83(986):777-9
2.Murre J, Dros J. Replication and Analysis of Ebbinghaus' Forgetting Curve. PLoS One. 2015;10(7):e0120644.
3.Ebbinghaus H. Über das Gedächtnis. Untersuchungen zur experimentellen psychologie. Leipzig: Duncker & Humblot; 1885
4. Sikström S. Forgetting curves: implications for connectionist models. Cogn Psychol. 2002;45(1):95-152
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