Fish Can Recognize and Remember Human Faces

By Jeanna Bryner, Live Science Managing Editor | June 7, 2016 02:01pm ET

A wee-brained tropical fish can distinguish between human faces in a lineup, researchers have found. This is the first time such an ability has been shown in fish.

Recognizing human faces is a difficult task. Because nearly all human faces have the same basic attributes, recognizing a face requires distinguishing subtle differences in facial features, said Cait Newport, a zoologist and Marie Curie research fellow at the University of Oxford.

In fact, past research has shown that a select few animals — including horses, cows, dogs and even some birds, such as pigeons — can successfully complete such a task. All of those animals, however, have a neocortex, or neocortex-like structures. The neocortex is a part of the brain that contains a visual-processing region as well as the fusiform gyrus, which is thought to be heavily involved in facial processing, the researchers noted. 

"Most animals tested possess a neocortex and have been domesticated, and may, as a result, have experienced evolutionary pressure to recognize their human [caregivers]," Newport and her colleagues wrote in today's (June 7) issue of the journal Scientific Reports.

To see whether an animal with a simpler brain — one lacking a neocortex — could recognize faces, the researchers turned to archerfish (Toxotes chatareus). This species is known for relying on vision to detect flying land animals, such as insects, and proceeding to spit jets of water at the aerial prey to knock it down, the researchers wrote.

Newport and her colleagues trained archerfish to select the "correct" image of a human face on a computer screen above their aquarium; for this fish, spitting a jet of water at an image is akin to pointing at it.

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