Body-relative horizontal–vertical anisotropy in human representations of traveled distances

Abstract

A growing number of studies investigated anisotropies in representations of horizontal and vertical spaces. In humans, compelling evidence for such anisotropies exists for representations of multi-floor buildings. In contrast, evidence regarding open spaces is indecisive. Our study aimed at further enhancing the understanding of horizontal and vertical spatial representations in open spaces utilizing a simple traveled distance estimation paradigm. Blindfolded participants were moved along various directions in the sagittal plane. Subsequently, participants passively reproduced the traveled distance from memory. Participants performed this task in an upright and in a 30° backward-pitch orientation. The accuracy of distance estimates in the upright orientation showed a horizontal–vertical anisotropy, with higher accuracy along the horizontal axis compared with the vertical axis. The backward-pitch orientation enabled us to investigate whether this anisotropy was body or earth-centered. The accuracy patterns of the upright condition were positively correlated with the body-relative (not the earth-relative) coordinate mapping of the backward-pitch condition, suggesting a body-centered anisotropy. Overall, this is consistent with findings on motion perception. It suggests that the distance estimation sub-process of path integration is subject to horizontal–vertical anisotropy. Based on the previous studies that showed isotropy in open spaces, we speculate that real physical self-movements or categorical versus isometric encoding are crucial factors for (an)isotropies in spatial representations.

Visibility matters during wayfinding in the vertical

“…These findings led to Jeffery et al bio-coded cognitive map hypothesis, postulating that representations of 3D space are subject to anisotropy, such that information along the horizontal dimension is encoded more precisely than information in the vertical space 5 . Research conducted in multilevel buildings present supporting evidence of this hypothesis 12 , 17 – 21 . Although this extensive body of research provides important insights into mental representations of 3D spaces, far fewer studies have investigated how visibility of 3D space directly affects wayfinding behavior and performance.…”

“…In principle, our experimental design does not allow us to draw inferences concerning the mental representation of the multilevel environments. There are many open questions regarding, for example, vertical versus horizontal anisotropy 5 , 20 , 21 and the representation of hierarchical environments 12 , 22 – 26 that are related to our study but cannot be addressed due to our choice of task structure and the use of desktop VR.…”

“…With regards to desktop VR, movement using visual motion does not provide users with idiothetic cues that can form the basis of the spatial representation of large 3D environments 21 . Although desktop VR has been used to elicit realistic trajectories in locomotion 33 and evacuation tasks 48 , it is possible that participants in the present study would have searched for destinations in a different manner if, for example, their view of the environment was not attached to an avatar that they moved with their hands via the control interface.…”

“…The importance of the vertical dimension for wayfinding has also been investigated in terms of anisotropies 5 , 20 , 21 and hierarchical environments 12 , 22 – 26 in 3D space. Both of these research areas emphasize the roles of different aspects of spatial representation for learning during wayfinding.…”

Distorted mental spatial representation of multi-level buildings - Humans are biased towards equilateral shapes of height and width

“…In the study, the participants had to estimate the perceived travelled distance relative to a reference stimulus. It was found that the estimation-errors depended on the movement direction and the authors further concluded that the anisotropy was more likely to be body rather than earth-centered 3 . Biases towards the horizontal plane have also been reported in other ground based animals such as canine 4 and rat 5 .…”