Judging beforehand the possibility of passing under obstacles without motion: the influence of egocentric and geocentric frames of reference

• Published in: Experimental brain research Vol. 185; no. 4; pp. 673 - 680
• Main Authors: Bringoux, L., Robic, G., Gauthier, G. M., Vercher, J. L.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-03-2008; Springer; Springer Nature B.V; Springer Verlag
• Subjects: Adult; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Cognitive science; Eye and associated structures. Visual pathways and centers. Vision; Female; Fundamental and applied biological sciences. Psychology; Gravity Sensing - physiology; Humans; Judgment - physiology; Male; Motion; Neurology; Neuroscience; Neurosciences; Orientation - physiology; Psychomotor Performance - physiology; Research Article; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Space Perception - physiology; Vertebrates: nervous system and sense organs; Egocentric; Gravity Referenced Eye Level; Geocentric; Body orientation; Spatial perception; Frame of reference; Human; Body perception; Obstacle; Orientation; Eye; Visual system; Tilt; Gravity; egocentric; geocentric
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-007-1194-7

Previous studies have shown that the perception of the earth-based visual horizon, also named Gravity Referenced Eye Level (GREL), is modified by body tilt around a trans-ocular axis. Here, we investigated whether estimates of the elevation of a luminous horizontal line presented on a screen in otherwise darkness and estimates of the possibility of passing under are identically related to body tilt in absence of motion. Results showed that subjects overestimated the elevation of the projected line, whatever their body orientation. In the same way, subjects also overestimated their capacity of passing under the line. Both estimates appeared as a linear function of body tilt, that is, forward body tilt yielded increased overestimations, and backward body tilt yielded decreased overestimations. More strikingly, the linear effect of body tilt upon these estimates is comparable to that previously observed for direct GREL judgements. Overall, these data strongly suggest that the perception of the elevation of a visible obstacle and the perception of the ability of passing under in otherwise darkness shared common processes which are intimately linked to the GREL perception. The effect of body tilt upon these perceptions may illustrate an egocentric influence upon the semi-geocentric frame of reference required to perform the task. Possible interactions between egocentric and geocentric frames of reference are discussed.