Loop M S, Bruce L L
Science. 1978 Mar 17;199(4334):1221-2. doi: 10.1126/science.628838.
Adult cats were trained to discriminate blue from green and gray. Although the cats could discriminate the intensity of stimuli whose areas ranged from 33 to 0.36 square centimeters they could not discriminate color when the stimulus was 0.36 square centimeter (less than 20 degrees visual angle). This influence of stimulus size may account for both positive and negative results of previous studies.
成年猫接受训练以区分蓝色与绿色和灰色。尽管这些猫能够区分面积从33平方厘米到0.36平方厘米的刺激强度，但当刺激面积为0.36平方厘米（小于20度视角）时，它们无法区分颜色。刺激大小的这种影响可能解释了先前研究的正反两方面结果。
