Previous studies focused on the comparison between VR models and 2D atlas or lacked the assessment of spatial ability11 − 13,17−21, while little attempt has been made to compare the VR models with cadaver models and 2D atlas in the same trial. Our study is the first randomized controlled trial that compare these three methods at the same time through both objective assessments and subjective assessments, which is designated as “various question types”16. The objective assessments comprised a theory test and an identification test. The latter is a crucial part to assess participants’ spatial ability since structure identification outweighs theoretical knowledge in the study of anatomy, and it is a predictor of improved learning outcomes following 3D learning16,22.
The results of the objective assessment demonstrated that VR simulation learning had equivalent efficiency in anatomical learning as cadaver skull and atlas, despite the relative simplicity of the 3D VR model used in this study, lacking texture and haptic feedback. The stereoscopic three-dimensionality of 3D VR model directly incorporates the intrinsic spatial relationships of the anatomical sites studied, and thus may confer a spatial knowledge advantage21, which is consistent with the insignificant higher post-identification score of VR group than the other two groups. Subjective evaluation of VR group and cadaver group also showed a more positive attitude towards learning model than 2D atlas group. Responses indicated that the two groups unanimously agreed with the enjoyment, teaching efficacy and authenticity of their skull models. Novel interventions usually arouse participants’ curiosity and lead to better results and all participants were willing to promote the use of VR model in anatomy education. Similarly, previous studies comparing 3D VR model with traditional 2D teaching method also reported that VR was evaluated as a more enjoyable and useful educational tool11,21,23.
Cadavers offer high realism, haptic feedback, and the opportunity to use real instruments and tools, which is thought to be the gold standard in anatomical learning24 − 26, particularly in surgery27. However, they are expensive, limited resource and offer no objective feedback of skill. 3D VR models, which are able for rapid and feedback-based modification, offer an opportunity for repetitive practice23. Another advantage of VR is that students are able to observe and receive instant visual feedback based on pre-defined practical tasks28. Critiques argued that this approach lacked the expert guidance during the learning process which play an important role in forming the basic framework29. In fact, teachers could also assess students’ learning progress and mistakes through digital reports to further strengthen students’ skills. What’s more, participants in our trial conducted a self-learning in the absence of guidance and gain substantial progress in anatomical knowledge, which is consistent with previous study30. It suggested that individuals’ self-learning at their private places is a feasible way to implement VR simulation learning without constrains of places or time30. In addition, 3D models are likely to enhance rather than replace lecture-based teaching by experts23. We could move the initial part of the learning curve from practice on cadavers to VR simulation, allowing the participants to practice the procedure and acquire basic skills before using expensive lab facilities30.
In our trial, the scores of cadaver skull group showed no statistically significant differences from those of VR group and atlas group in this trial. This discrepancy might partially result from structural variation and damaged structures in the cadaveric skulls, and the negative psychological reaction in participants triggered by the cadaveric skulls 31,32. Besides, we combined lecture and model learning together to simulate the real learning process. The lecture allowed participants to get hints about the correct answers and narrow the differences between the three groups. What’s more, all these participants practiced and took the examination together introducing competitive element.
Our study incorporated a room-scale HMD unit, which is available for individuals. Many more manipulations can be achieved easily, such as rotating to a suitable view, isolating a single cranial bone and zooming in/out the model, making it a better tool in understanding of difficult anatomical structures. Participants in the VR group only received a 2-min instruction about the VR equipment, which suggested that the operation of our equipment and software can be quickly adapted to. This HMD unit provides a completely immersive experience with a high display resolution, a high refresh rate, and a more precise, low-latency constellation head tracking capability. Previous study reported a high adverse rate in VR group (headaches 25%; blurred vision 35%)20, while the adverse rate was lower in our trial (headaches 20%, blurred vision 4%). It can be inferred that the discomforts caused by the activities in the virtual environment was relieved with increased resolution and lower latency. Large amount of knowledge to memorize, compact exam arrangement and unfamiliarity with learning material might bring too much burden to the brain, causing headache, blurred vision and other discomforts in all groups.
The results suggest two minor findings. First, male participants scored higher than female participants in post-intervention identification test. Previous studies have shown that individual spatial ability is associated with improved learning outcomes following small-group 3D learning22,33, which is consistent with our finding. One possible explanation is that males have stronger mental rotation, which is closely associated spatial imagination34. Similar results between genders were observed in VR group, indicating VR model learning relies on good spatial imagination partially. Second, 2D atlas tended to improve participants’ understanding of structures at superior view. A possible explanation may be that the structures at superior seems to be at the same plane when observing from the top of the skull and they can be well painted on atlas.
Our study had several limitations. First, the single-institution sample was small as we only recruited 73 students at their third year from PUMC, who just finished their pre-medical course. Further studies should be performed to investigate a multi-institution sample and broader participants at different levels, such as resident physicians, nursing students, and related educators. Second, our study is limited to a 30-min self-directed learning and failed to let the participants get used to the virtual world without learning model in advance. Third, we failed to disclosure the aim of our study in advance as participant required access to the different interventions. The study design does not represent a single- or double-blinded trial. Knowledge of the grouping and interventions affected students’ performance to some extent.