Department of Biology, Lund University, Lund, Sweden.
PLoS One. 2013;8(1):e54650. doi: 10.1371/journal.pone.0054650. Epub 2013 Jan 18.
Birds have excellent spatial acuity and colour vision compared to other vertebrates while spatial contrast sensitivity is relatively poor for unknown reasons. Contrast sensitivity describes the detection of gratings of varying spatial frequency. It is unclear whether bird brightness discrimination between large uniform fields is poor as well. Here we show that budgerigars (Melopsittacus undulatus) need a Michelson contrast of 0.09 to discriminate between large spatially separated achromatic fields in bright light conditions. This is similar to the peak contrast sensitivity of 10.2 (0.098 Michelson contrast) for achromatic grating stimuli established in earlier studies. The brightness discrimination threshold described in Weber fractions is 0.18, which is modest compared to other vertebrates.
鸟类在空间敏锐度和色彩视觉方面比其他脊椎动物出色,而空间对比敏感度相对较差,原因未知。对比敏感度描述了对不同空间频率的光栅的检测。目前尚不清楚鸟类在大而均匀的视野中对亮度的辨别能力是否也较差。在这里,我们发现虎皮鹦鹉(Melopsittacus undulatus)需要 0.09 的米歇尔逊对比度才能在明亮的光线条件下辨别大的空间分离的非彩色场。这与之前研究中确定的 10.2(0.098 米歇尔逊对比度)的非彩色光栅刺激的峰值对比敏感度相似。以韦伯分数表示的亮度辨别阈值为 0.18,与其他脊椎动物相比,这一阈值适中。