Natures wonders: archer fish recognize human faces (Introduction)

by David Turell @, Tuesday, June 07, 2016, 20:40 (1198 days ago) @ David Turell

It has been demonstrated that crows can distinguish human faces. Now archer fish have been shown to have the same ability. The fish have a more primitive brain, but archer fish have the special ability to hit a moving insect with a stream of water to get a meal.:

"The researchers found that fish, which lack the sophisticated visual cortex of primates, are nevertheless capable of discriminating one face from up to 44 new faces. The research provides evidence that fish (vertebrates lacking a major part of the brain called the neocortex) have impressive visual discrimination abilities.

"In the study, archerfish—a species of tropical fish well known for its ability to spit jets of water to knock down aerial prey - were presented with two images of human faces and trained to choose one of them using their jets. The fish were then presented with the learned face and a series of new faces and were able to correctly choose the face they had initially learned to recognize. They were able to do this task even when more obvious features, such as head shape and colour, were removed from the images.

"The fish were highly accurate when selecting the correct face, reaching an average peak performance of 81% in the first experiment (picking the previously learned face from 44 new faces) and 86% in second experiment (in which facial features such as brightness and colour were standardized).

"Dr Newport said: 'Fish have a simpler brain than humans and entirely lack the section of the brain that humans use for recognizing faces. Despite this, many fish demonstrate impressive visual behaviours and therefore make the perfect subjects to test whether simple brains can complete complicated tasks.

"'Archerfish are a species of tropical freshwater fish that spit a jet of water from their mouth to knock down insects in branches above the water. We positioned a computer monitor that showed images of human faces above the aquariums and trained them to spit at a particular face. Once the fish had learned to recognize a face, we then showed them the same face, as well as a series of new ones.

"'In all cases, the fish continued to spit at the face they had been trained to recognize, proving that they were capable of telling the two apart. Even when we did this with faces that were potentially more difficult because they were in black and white and the head shape was standardized, the fish were still capable of finding the face they were trained to recognize.

"'The fact that archerfish can learn this task suggests that complicated brains are not necessarily needed to recognize human faces. Humans may have special facial recognition brain structures so that they can process a large number of faces very quickly or under a wide range of viewing conditions.'

"Human facial recognition has previously been demonstrated in birds. However, unlike fish, they are now known to possess neocortex-like structures. Additionally, fish are unlikely to have evolved the ability to distinguish between human faces. "

Comment: Surprising but if an archer fish can compute the spot to shoot a steam of water at a flying insect, it has some advanced computational equipment in its tiny brain. The other issue is how did the archer learn to do this to get its meals? How did it eat while learning to shoot? Another puzzle from life's complexity.

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