Cobo-Lewis A B, Siatkowski R M, Laviña A M, Marquez L C
Department of Psychology, School of Medicine, University of Miami, Florida, USA.
Invest Ophthalmol Vis Sci. 1997 Dec;38(13):2800-9.
The size of a retinal image is inversely related to the distance to the object that generates the image. Normal subjects therefore exhibit size constancy, in which the perceived size of an image is scaled according to its perceived distance. Albinos usually have such poor binocular vision that they perform very poorly on clinical tests for stereopsis. To investigate the functional consequences of this poor stereopsis, we investigated whether stereopsis in these subjects could support size constancy.
The stereothresholds of 10 albinos and 12 normal control subjects were measured. The presence of absence of size constancy was investigated by having subjects equate the subjective size of stereoscopically presented images whose image disparity indicated that they were at different distances.
Laboratory results indicated that eight albinos (including five whose clinical tests indicated a lack of stereopsis) had measurable stereopsis of several thousand are seconds or better. Of these, four also exhibited size constancy.
Albinos who do not demonstrate stereopsis on clinical tests can have stereoscopic perception that commonly used clinical tests do not detect. Moreover, some of these patients even use this poor stereopsis in judging the size of stereoscopically presented images.
视网膜图像的大小与产生该图像的物体的距离成反比。因此，正常受试者表现出大小恒常性，即图像的感知大小会根据其感知距离进行缩放。白化病患者通常双眼视力很差，在立体视觉的临床测试中表现非常糟糕。为了研究这种糟糕的立体视觉的功能后果，我们调查了这些受试者的立体视觉是否能支持大小恒常性。
测量了10名白化病患者和12名正常对照受试者的立体视觉阈值。通过让受试者使立体呈现的图像的主观大小相等来研究大小恒常性的有无，这些图像的视差表明它们处于不同的距离。
实验室结果表明，8名白化病患者（包括5名临床测试显示缺乏立体视觉的患者）具有可测量的立体视觉，为几千角秒或更好。其中，4名患者也表现出大小恒常性。
在临床测试中未表现出立体视觉的白化病患者可能具有常用临床测试检测不到的立体视觉感知。此外，这些患者中的一些人甚至在判断立体呈现图像的大小时会利用这种较差的立体视觉。
