title: Human spatial orientation in non-stationary environments: relation between self-turning perception and detection of surround motion.
abstract: We investigated the relative weighting of vestibular, optokinetic and podokinetic (foot and leg proprioceptive) cues for the perception of self-turning in an environment which was either stationary (concordant stimulation) or moving (discordant stimulation) and asked whether cue weighting changes if subjects (Ss) detect a discordance. Ss (N = 18) stood on a turntable inside an optokinetic drum and turned either passively (turntable rotating) or actively in space at constant velocities of 15, 30, or 60°/s. Sensory discordance was introduced by simultaneous rotations of the environment (drum and/or turntable) at ±{5, 10, 20, 40, 80}% of self-turning velocity. In one experiment, Ss were to detect these rotations (i.e. the sensory discordance), and in a second experiment they reported perceived angular self-displacement. Discordant optokinetic cues were better detected, and more heavily weighted for self-turning perception, than discordant podokinetic cues. Within Ss, weights did not depend on whether a discordance was detected or not. Across Ss, optokinetic weights varied over a large range and were negatively correlated with the detection scores: the more perception was influenced by discordant optokinetic cues, the poorer was the detection score; no such correlation was found among the podokinetic results. These results are interpreted in terms of a "self-referential" model that makes the following assumptions: (1) a weighted average of the available sensory cues both determines turning perception and serves as a reference to which the optokinetic cue is compared; (2) a discordance is detected if the difference between reference and optokinetic cue exceeds some threshold; (3) the threshold value corresponds to about the same multiple of sensory uncertainty in all Ss. With these assumptions the model explains the observed relation between optokinetic weight and detection score.
authors: Sektion Neurophysiologie, Universität Ulm, Albert Einstein Allee 47, 89081 Ulm, Germany.
authors: Reinhart
authors: R
authors: Jürgens
authors: Wolfgang
authors: W
authors: Becker
mesh_terms: D000328:Adult; D001828:Body Image; D005260:Female; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D055815:Young Adult