Douglas R H, Eva J, Guttridge N
Department of Optometry and Visual Science, City University, London, U.K.
Behav Brain Res. 1988 Sep 1;30(1):37-42. doi: 10.1016/0166-4328(88)90006-x.
This study examines whether fish are able to judge the real size of objects taking distance into account, or if size judgements are based purely on the angle objects subtend on the retina. Goldfish were trained to discriminate between 2 targets which differed from one another only in their diameters (5 cm and 10 cm), presented initially equidistantly from the fish. A choice of the correct target was rewarded either by food or by access to other fish. Following successful training, the targets were shifted so that they both subtended the same visual angle. The fish continued to choose the target to which they had been trained, showing that they display size constancy. This ability was present in both monocular and binocular animals.
本研究探讨鱼类是能够考虑距离因素来判断物体的实际大小，还是其大小判断仅仅基于物体在视网膜上所张的角度。金鱼接受训练，以区分两个仅直径不同（5厘米和10厘米）的目标，最初这两个目标与金鱼的距离相等。选择正确目标会得到食物奖励或与其他鱼类接触的机会。成功训练后，将目标移动，使它们所张的视角相同。金鱼继续选择它们接受过训练的目标，表明它们具有大小恒常性。单眼和双眼的金鱼都具备这种能力。
