## 1 Introduction  
Emerging technologies have transformed the world of work and increasingly are making desolate and hard-to-reach environments, such as outer space, deep oceans, and polar regions, more accessible to humans [1, 2, 3, 4, 5, 6]. The visuospatial conditions of these environments may adversely affect the spatial cognitive processing of people in such environments, hindering their ability to work safely and productively [7, 8, 9, 10]. In normal environments, familiar natural or manmade landmarks, such as roads, people, cars, buildings, streetlights, and trees, offer spatial cues to help individuals not just to create a clear mental representation of the area, but also to relate to the various spatial elements, judge their size and position, and determine the speed of a moving object [11, 12]. Such cues are not available in remote and desolate places devoid of landmarks, such as the North and South Poles and deserts. Likewise, the alien terrains of the Earth's moon or Mars lack familiar spatial landmarks. To help humans better adapt to such altered conditions, reliable and cost-effective training technologies are needed. Therefore, to inform design principles for such technologies, examining how a lack of visuo-spatial cues affects spatial perception is also critical.  
Virtual reality technology has been employed by multiple studies to simulate extreme physical conditions in order to investigate spatial cognitive processing in such conditions [13; 14; 15]. For instance, some studies [16; 17] simulated a multi-module space station in VR and concluded that spatial tests displayed in VR can predict work and navigation performance in such environments. Other studies [18; 19] have successfully employed VR to simulate extreme environments and found that VR has the potential to serve as a training system to help people adapt to a microgravity environment. In fact, applying VR-based simulations to test and train spatial abilities of astronauts has been recommended as a cost-effective and safer approach than conventional parabolic flights and drop towers [19; 20].  
Newly developed training tools to address the impact of limited spatial cues will need fundamental research to examine their efficacy. Such knowledge is critical to informing the design and development of training tools to prepare a broad population for space exploration. Although extreme environments pose a range of challenges (e.g., microgravity or extreme temperature), this study focuses on potential challenges of operating in environments that lack familiar visual cues. Specifically, we examine how the absence of familiar spatial cues influences spatial perception. Spatial perception, in the context of this study, refers to the ability to accurately estimate the distance and scale of objects in space [21]. This is particularly important under extreme conditions. Misinterpreting size and distance may not only hinder work productivity but also result in life-threatening conditions. In 1997, a Russian Progress supply spacecraft and the Russian Mir space station collided due to human error in estimating distance and size ([22], cited by [23]). To avoid catastrophic effects, there is an urgent need to understand how limited visual cues or the absence of visual cues affects human spatial perception in extreme conditions.  
Previous research has established that in a real-world environment people judge size and distance based on visual cues such as landmarks. Judgments of size and distance can be adversely affected when visual cues are limited or incomplete. Our study compares the accuracy of estimating spatial dimensions across three levels of visual cue availability using virtual reality environments. We hypothesize that a higher availability of familiar visual cues will facilitate more accurate perceptions of object distance and size.