Date Published: March 18, 2019
Publisher: Public Library of Science
Author(s): Antoine Coutrot, Sophie Schmidt, Lena Coutrot, Jessica Pittman, Lynn Hong, Jan M. Wiener, Christoph Hölscher, Ruth C. Dalton, Michael Hornberger, Hugo J. Spiers, Laura Zamarian.
Virtual reality environments presented on tablets and smartphones have potential to aid the early diagnosis of conditions such as Alzheimer’s dementia by quantifying impairments in navigation performance. However, it is unclear whether performance on mobile devices can predict navigation errors in the real world. We compared the performance of 49 participants (25 females, 18-35 years old) at wayfinding and path integration tasks designed in our mobile app ‘Sea Hero Quest’ with their performance at similar tasks in a real-world environment. We first performed this experiment in the streets of London (UK) and replicated it in Paris (France). In both cities, we found a significant correlation between virtual and real-world wayfinding performance and a male advantage in both environments, although smaller in the real world (Cohen’s d in the game = 0.89, in the real world = 0.59). Results in London and Paris were highly similar, and controlling for familiarity with video games did not change the results. The strength of the correlation between real world and virtual environment increased with the difficulty of the virtual wayfinding task, indicating that Sea Hero Quest does not merely capture video gaming skills. The fact that the Sea Hero Quest wayfinding task has real-world ecological validity constitutes a step toward controllable, sensitive, safe, low-cost, and easy to administer digital cognitive assessment of navigation ability.
Virtual reality (VR) provides a powerful means to study and quantify how humans navigate, because the properties of a virtual environment can be completely controlled and repeated across participants. Since the late nineties, it has been a critical tool to understanding how brain regions support navigation and unveiling the structural and functional neural correlates of spatial navigation [1–4]. VR tests of spatial cognition have proved more sensitive in identifying spatial navigation deficits in patient populations compared to more classic visuospatial ‘pencil-and-paper’ tests like the Mental Rotation Test . VR has the added advantage to be a less costly and safer alternative to real-world navigation tests, which are time and space consuming, as well as difficult to administer to a population sometimes less able to walk . Until recently, most VR used in research was presented on a desktop display and movement controlled via a joystick or keyboard. Such an interface presents difficulties for older people, less exposed to technology than younger participants . However, with the advent of tablet and smart-phone touch screen mobile devices, older participants have found engaging in VR tasks much easier and intuitive than with desktop computers [8, 9]. As a consequence, mobile devices have recently been used in several fields such as neuropsychological assessment , stroke rehabilitation  and mental health . We recently developed a VR navigation task for mobile and tablet devices—Sea Hero Quest—with the aim that this may provide an early diagnostic tool for Alzheimer’s Disease (AD) . For this test to be useful it is important that it has real-world validity, with errors on the VR task predicting errors in real-world navigation experience.
This study has been approved by UCL Ethics Research Committee. The ethics project ID number is CPB/2013/015. Written consent was obtained from each participant and the data were analyzed anonymously. Participants were tested on specific levels from Sea Hero Quest  on a tablet, and then on equivalent tasks in the real world, see Fig 1. Participants were also asked to answer a few demographic questions. We first ran this experiment in London in summer/fall 2017. We then replicated it with a different team in Paris in spring 2018. The whole experiment lasted around three hours.
Table 1 reports the difficulty of each wayfinding route in the real-world task as the percentage of goals reached by the participants before the time limit. This goes from 99% in London (100% in Paris) for route 1 down to 74% in London (84% in Paris) for route 6. Table 1 also reports the difficulty of each wayfinding level in the video game task as the percentage of participants that managed to complete the level before the helping arrow appeared. 100% participants successfully completed the first training level while only 47% participants in London (40% in Paris) completed level 43. Interestingly, level 11 seemed harder than level 16, which might be due to level 11 requiring participants to turn back to meet the goals in order, which was not the case in level 16 (see S1 Fig).
We report evidence that wayfinding navigation performance on a mobile app-based VR navigation task (Sea Hero Quest) is significantly correlated with performance in a real-world city street wayfinding task. We directly compared participants performance at a subset of Sea Hero Quest wayfinding levels with their performance at an equivalent task in the Covent Garden area, London. We found a strong correlation between the distance participants travelled in the video game (in pixels) and in the real-world street network (in meters, measured by a GPS device). We replicated this result with another set of participants in the Montparnasse area, Paris. The high similarity of the results in the two cities is a strong indicator of the robustness of the results presented above. Our findings are consistent with a number of studies that showed that spatial navigation assessment in a desktop VR [15, 16, 18, 20, 22, 23, 27] and immersive VR [17, 42] environments transferred well to the real world, and extend them to tablet device presentation and real-world spatial task spanning complex street networks. However skill assessment don’t always generalize from VR to the real world. For instance reading skills assessed in a digital device can be partially predicted by participant’s ability to perform basic computer tasks . The similarity both in term of performance and of gender difference of this study with the original large scale Sea Hero Quest study  suggests that our findings hold true not simply in small cohorts but on a population level.