This Tropical Fish Can Be Taught to Recognize Human Faces

New study trained fish to spit at human faces

Study reveals archerfish can recognize human faces

Though many may mock a fish's short memory, the creatures can still learn some astounding things. Researchers at the University of Oxford and the University of Queensland recently discovered that the small tropical archerfish can be taught to accurately recognize human faces, Arielle Duhaime-Ross reports for The Verge

In the study, published this week in the journal Scientific Reports, researchers describe training the archerfish. While it would be hard for most fish to communicate what they see, the archerfish has a nifty trick up its gills: the ability to spit little jets of water from its mouth. 

The researchers displayed images of two faces side-by-side on a screen dangled above the fish’s tank—one familiar, one unknown. The fish was then supposed to spit water at the correct image for a treat.

81 percent of the time, the archerfish could recognize the same faces in color but were even more accurate with black and white images.

“I think it’s really fascinating that they have these supposedly simple brains," study author Cait Newport tells Victoria Turk for Motherboard. "But they’re still able to use them for really complicated tasks, and we probably just don’t give them enough credit.”

The researchers hope that these little fish can help uncover how humans pull off this complex neurological trick.

There are currently two major ideas for how human brains recognize faces, writes Turk. Some believe the credit goes to complex, specialized circuitry that the brain evolved over time, but others think that humans simply learned the skill.

“We wanted to disentangle these two ideas and see if we could use another species to figure out if we do in fact need really specialized cells, or if maybe something else that doesn’t have these specialized cells can learn this task,” Newport tells Turk. “That’s why we turned to fish, because they have no evolutionary need to recognize human faces, and they lack this entire section of the brain—the neocortex.”

This isn’t the first time that Newport and her team have taught fish to recognize faces. Last October, she and her team published a similar study that demonstrated a coral reef fish called the Ambon damselfish can distinguish between individuals of its own species. In that case, the fish were aided by their ability to see ultraviolet light. While damselfish appear yellow to the human eye, their faces are actually speckled with unique facial patterns that appear under UV light, Mary Bates reports for National Geographic.

"Categorical perception is thought to allow animals to make quick decisions about an image or stimulus," study author Ulrike Siebeck told Bates. "In nature, this could be the vital decision about whether an approaching animal is classed as a predator or a harmless animal."

These studies suggest that the ability to recognize faces does not rely on complex neurological pathways. Facial recognition is either a less difficult task than believed or can be accomplished using more basic parts of the brain. These findings could also be applied to refine facial recognition computer programs, Turk reports.

“It [raises] the question as to why the human system is so complicated if a really simple system can do it,” Newport tells Turk.

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