Kaufman Lloyd, Vassiliades Vassias, Noble Richard, Alexander Robert, Kaufman James, Edlund Stefan
Department of Psychology, C. W. Post Campus, Long Island University, Brookville, NY, USA.
Spat Vis. 2007;20(1-2):155-75. doi: 10.1163/156856807779369698.
The elevated moon usually appears smaller than the horizon moon of equal angular size. This is the moon illusion. Distance cues may enable the perceptual system to place the horizon moon at an effectively greater distance than the elevated moon, thus making it appear as larger. This explanation is related to the size-distance invariance hypothesis. However, the larger horizon moon is usually judged as closer than the smaller zenith moon. A bias to expect an apparently large object to be closer than a smaller object may account for this conflict. We designed experiments to determine if unbiased sensitivity to illusory differences in the size and distance of the moon (as measured by d') is consistent with SDIH. A moon above a 'terrain' was compared in both distance and size to an infinitely distant moon in empty space (the reduction moon). At a short distance the terrain moon was adjudged as both closer and smaller than the reduction moon. But these differences could not be detected at somewhat greater distances. At still greater distances the terrain moon was perceived as both more distant and larger than the reduction moon. The distances at which these transitions occurred were essentially the same for both distance and size discrimination tasks, thus supporting SDIH.
高悬的月亮通常看起来比角大小相同的地平线上的月亮小。这就是月亮错觉。距离线索可能使感知系统将地平线上的月亮置于比高悬的月亮更远的有效距离处，从而使其看起来更大。这种解释与大小 - 距离不变性假设有关。然而，较大的地平线上的月亮通常被判断为比较小的天顶月亮更近。期望一个明显大的物体比较小的物体更近的偏差可能解释了这种冲突。我们设计了实验来确定对月亮大小和距离的错觉差异的无偏差敏感性（由d'测量）是否与大小 - 距离不变性假设一致。将“地形”上方的月亮在距离和大小上与空空间中无限远的月亮（缩小月亮）进行比较。在短距离内，地形月亮被判定为比缩小月亮更近且更小。但在稍远的距离上，这些差异无法被检测到。在更远的距离上，地形月亮被感知为比缩小月亮更远且更大。对于距离和大小辨别任务，这些转变发生的距离基本相同，从而支持了大小 - 距离不变性假设。
