Influence of panoramic cues during prolonged roll-tilt adaptation on the percept of vertical

Abstract

The percept of vertical, which mainly relies on vestibular and visual cues, is known to be affected after sustained whole-body roll tilt, mostly at roll positions adjacent to the position of adaptation. Here we ask whether the viewing of panoramic visual cues during the adaptation further influences the percept of the visual vertical. Participants were rotated in the frontal plane to a 90° clockwise tilt position, which was maintained for 4-minutes. During this period, the subject was either kept in darkness, or viewed panoramic pictures that were either veridical (aligned with gravity) or oriented along the body longitudinal axis. Errors of the subsequent subjective visual vertical (SVV), measured at various tilt angles, showed that the adaptation effect of panoramic cues is local, i.e. for a narrow range of tilts in the direction of the adaptation angle. This distortion was found irrespective of the orientation of the panoramic cues. We conclude that sustained exposure to panoramic and vestibular cues does not adapt the subsequent percept of vertical to the direction of the panoramic cue. Rather, our results suggest that sustained panoramic cues affect the SVV by an indirect effect on head orientation, with a 90° periodicity, that interacts with a vestibular cue to determine the percept of vertical.

Panoramic Uncertainty in Vertical Perception

“…Rich visual scenes typically contain various panoramic cues, such as houses, trees, or the horizon. These cues unambiguously indicate which direction is up and hence can provide the brain with information about gravity direction ( van der Schaaf and van Hateren, 1996 ; Coppola et al, 1998 ; Girshick et al, 2011 ; Pomante et al, 2021 ). More impoverished visual scenes, lacking clear panoramic cues, also affect the percept of vertical ( Ebenholtz and Callan, 1980 ; Li and Matin, 2005a ).…”