Effects of mini-maps with different reference frames on polarity-free 3D spatial navigation: a behavioural and fNIRS study

Manned spaceflight and deep-sea exploration extend human activities to extreme environments lacking gravitational and visual polarity cues, where spatial disorientation frequently occurs. Mini-map studies largely focus on terrestrial environments, while reference frame design for polarity-free 3D space remains understudied. We constructed a symmetric virtual 3D space in which 31 participants completed four navigation conditions: no map, world-centred static, world-centred dynamic, and egocentric dynamic (EGO) map. Behavioural, subjective and fNIRS data were collected. Results showed significant condition effects on accuracy and reaction time. All three map conditions improved accuracy and reduced right fusiform gyrus deoxyhemoglobin versus no map. The EGO map with trajectory tracking and real-time heading alignment achieved superior accuracy, lower workload and higher usability by lowering path integration demands and reference switching costs. These findings provide support for navigation interface design for spaceflight, deep-sea operations and virtual reality.