Switching Between Egocentric and Allocentric Reference Frames: A Multimodal Study of Behavioural, Physiological, and Neural Mechanisms

Successful navigation relies on the flexible interaction between egocentric (body-centered) and allocentric (object-centered) spatial representations. A critical yet understudied component of this process is the ability to switch between spatial reference frames. In particular, little is known about how environmental structure and cognitive demands influence switching between egocentric and allocentric representations. To address this issue, we investigated visuospatial switching processes using a novel paradigm, the Ego–Allo Switching Task. Participants memorized triads of objects and subsequently provided relative distance judgments in both switching conditions (Ego-to-Allo, Allo-to-Ego) and non-switching conditions (Ego-Ego, Allo–Allo). Across three studies, we examined the behavioural, physiological, and neural mechanisms underlying spatial reference frame switching. Behavioural results (Study 1) showed that non-orthogonal environmental layouts selectively impair switching from allocentric to egocentric representations. Cognitive pupillometry (Study 2) further revealed that this transformation elicits greater cognitive load, as reflected by increased pupil dilation. Finally, fNIRS (Study 3) identified a fronto–parieto–temporal network supporting visuospatial switching, with the temporo-parietal junction emerging as a key hub for translating between reference frames. Together, these findings provide a multilevel account of spatial reference frame switching, revealing how environmental structure and cognitive demands jointly constrain the transformation between egocentric and allocentric representations.