阅读理解
While your pet fish may appear to be unaware of your presence, chances are that it knows you extremely well and can probably even identify you from a crowd of human faces!
To test if this was accurate, some scientists decided to study archerfish（喷水鱼）. These animals don't have a sophisticated（复杂的）brain that is necessary to recognize the slight differences between human facial features.
They began by presenting four archerfish with images of two human faces. Initially, the fish spit at both. However, they soon learned spitting water at the one selected by the researchers earned them a food treat. After that, they focused primarily on that image. The researchers then took the experiment one step further by introducing 44 other human faces to the mix.
To the researcher's astonishment, the trained archerfish were able to recall the learned image almost 81% of the time. And this accuracy improved to 86% when the researchers made the identification even harder, by replacing the colored photos with a set of black and white images and hiding the shape of the head.
The results of the study suggest that though having tiny brains, archerfish may have developed high visual discrimination abilities. While it is contrary to the previous theory that a sophisticated brain is necessary to recognize human faces, the researchers believe they do not recognize faces by recalling complex facial information like gender and identity, but more likely by discriminating between detailed patterns. Even so, the fact that these archerfish could “remember” those faces demonstrates that they have an impressive memory for details that lasts much longer than the originally-thought 3 seconds!
This is not the first time researchers have realized how “smart” fish are. Previous studies have shown that fish can recognize those fish they have “socialized” with previously, and even recall complex three-dimensional maps of their surroundings.
