Wu Jun, He Zijiang J, Ooi Teng Leng
Department of Psychological and Brain Sciences, University of Louisville, Louisville, KY 40292, USA.
Perception. 2005;34(9):1045-60. doi: 10.1068/p5416.
The eye level and the horizontal midline of the body trunk can serve, respectively, as references for judging the vertical and horizontal egocentric directions. We investigated whether the optic-flow pattern, which is the dynamic motion information generated when one moves in the visual world, can be used by the visual system to determine and calibrate these two references. Using a virtual-reality setup to generate the optic-flow pattern, we showed that judged elevation of the eye level and the azimuth of the horizontal midline of the body trunk are biased toward the positional placement of the focus of expansion (FOE) of the optic-flow pattern. Furthermore, for the vertical reference, prolonged viewing of an optic-flow pattern with lowered FOE not only causes a lowered judged eye level after removal of the optic-flow pattern, but also an overestimation of distance in the dark. This is equivalent to a reduction in the judged angular declination of the object after adaptation, indicating that the optic-flow information also plays a role in calibrating the extraretinal signals used to establish the vertical reference.
眼睛水平和身体躯干的水平中线可分别作为判断自我中心垂直和水平方向的参考。我们研究了光流模式，即在视觉世界中移动时产生的动态运动信息，是否能被视觉系统用于确定和校准这两个参考。通过使用虚拟现实装置来生成光流模式，我们发现，对眼睛水平的判断高度和身体躯干水平中线的方位偏向于光流模式的膨胀焦点（FOE）的位置。此外，对于垂直参考，长时间观察FOE降低的光流模式不仅会在去除光流模式后导致判断的眼睛水平降低，还会导致在黑暗中对距离的高估。这相当于适应后对物体判断的角度偏角减小，表明光流信息在校准用于建立垂直参考的视网膜外信号中也起作用。
