Changes in boundary extension effect during spatial confinement

Abstract

Changes in perception during space missions are usually attributed to microgravity. However, additional factors, such as spatial confinement, may contribute to changes in perception. We tested changes in scene perception using a boundary extension (BE) paradigm during a 105-day Earth-based space-simulation study. In addition to the close-up/wide-angle views used in BE, we presented two types of scenes based on the distance from the observer (proximal/distant scenes). In crew members (n = 6), we found that BE partly increased over time, but the size of BE error did not change in the control group (n = 22). We propose that this effect is caused by an increasing BE effect in stimuli that depict distant scenes and is related to spatial confinement. The results might be important for other situations of spatial confinement with restricted visual depth (e.g., submarine crew, patients confined to a bed). Generally, we found a larger BE effect in proximal scenes compared with the distant scenes. We also demonstrated that with no feedback, subjects preserve the level of the BE effect during repeated measurements.