The development of distance estimation in optic flow.
In three experiments we tested the ability of children aged 8 to 12 years and adults to locate a target in an optic texture flow projected onto the ground. During the exposure phase, a static target (diode) was lit up at 6 m or 8 m on the ground in front of the subject. During the pointing phase, the subject was asked to indicate the perceived location of the target with a laser pointer as soon as the target was switched off. In the first experiment, during both phases the optic texture (environment) was either motionless or approaching the subject. Results showed that target locations were significantly more underestimated within the moving texture than within the still texture. In the second experiment, a detailed error analysis showed that the differences of performance between children and adults were not due to differences in eye height. Errors can be described by a linear fit with the retinal speed of the optic flow surrounding the targets. Distance judgments improved from the age of 8 years onwards. In the last experiment we found the same kind of results with a receding texture and without stimulation in central vision. Results are discussed in terms of subject's capacity to compensate for the effect of linear vection produced by the optic flow.
Baumberger
Bernard
B
Experimental Psychology Laboratory of Perception, FPSE, University of Geneva, 40 boulevard du Pont d'Arve, CH 1205 Geneva 4, Switzerland. Bernard.Baumberger@pse.unige.ch
Flückiger
Michelangelo
M
D000328:Adult; D000375:Aging / Q000502:physiology; D001827:Body Height; D002648:Child; D015350:Contrast Sensitivity / Q000502:physiology; D004215:Distance Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D013028:Space Perception / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*