The effect of supine body position on human heading perception

Abstract

The use of virtual environments in functional imaging experiments is a promising method to investigate and understand the neural basis of human navigation and self-motion perception. However, the supine position in the fMRI scanner is unnatural for everyday motion. In particular, the head-horizontal self-motion plane is parallel rather than perpendicular to gravity. Earlier studies have shown that perception of heading from visual self-motion stimuli, such as optic flow, can be modified due to visuo-vestibular interactions. With this study, we aimed to identify the effects of the supine body position on visual heading estimation, which is a basic component of human navigation. Visual and vestibular heading judgments were measured separately in 11 healthy subjects in upright and supine body positions. We measured two planes of self-motion, the transverse and the coronal plane, and found that, although vestibular heading perception was strongly modified in a supine position, visual performance, in particular for the preferred head-horizontal (i.e., transverse) plane, did not change. This provides behavioral evidence in humans that direction estimation from self-motion consistent optic flow is not modified by supine body orientation, demonstrating that visual heading estimation is one component of human navigation that is not influenced by the supine body position required for functional brain imaging experiments.

Causal Inference in Multisensory Heading Estimation

“…Apart from the variability of dispersion observed in experiment I, the findings on dispersion are consistent with the literature: inertial dispersion is larger than visual dispersion, and patterns in dispersion show that the smallest values occur around the cardinal axes, with values increasing as the heading angle deviates away from these axes [17, 21, 22, 27]. …”

“…In a number of recent studies, both visual and inertial heading estimates were found to be biased away from the cardinal axes [21, 22, 27]. The present data show that visual heading estimates are on average also biased away from the fore-aft axis, in both experiments; inertial heading estimates were biased away from the cardinal axes in experiment I and biased towards the cardinal axes in experiment II.…”

Effects of visual stimulus characteristics and individual differences in heading estimation

“…A salient difference between stimuli used in different studies is the size of the FOV. The equipment used in past studies varied between head-mounted displays (Hummel, Cuturi, MacNeilage, & Flanagin, 2016), projection screens (de Winkel et al, 2015(de Winkel et al, , 2017Gu, DeAngelis, & Angelaki, 2007), LCD screens (Crane, 2014;Cuturi & MacNeilage, 2013), and plain monitors (d' Avossa & Kersten, 1996;W. H. Warren & Kurtz, 1992), varying in resolution and display size.…”

“…For instance, van den Berg and Brenner (1994a) found a bias toward the fore-aft axis when the depth of the horizon was reduced. Most studies reporting a bias away from the fore-aft axis used clouds of dots (Crane, 2012;Cuturi & MacNeilage, 2013;Hummel et al, 2016), while studies reporting a bias toward the fore-aft axis mostly relied on displays with a ground plane (de Winkel et al, 2015;Li et al, 2002;W. H. Warren & Kurtz, 1992).…”

“…The latter, featuring acceleration and deceleration phases, may be considered more naturalistic, as self-motion in the real world has similar characteristics (Butler et al, 2015). Most studies reporting overestimation used raised cosine-bell velocity profiles (Crane, 2012;Cuturi & MacNeilage, 2013;Hummel et al, 2016), whereas most studies reporting underestimation use constant velocity profiles (Johnston et al, 1973;Li et al, 2002;W. H. Warren & Kurtz, 1992).…”