Are fish really self-aware?

NEW YORK — Scientists report that a fish can pass a standard test of recognizing itself in a mirror, but does this decades-old test, designed to show self-awareness in animals, really do that?

Since the mirror test was introduced in 1970, scientists have found that relatively few animals can pass it. Chimps and orangutans can, says the test’s inventor, evolutionary psychologist Gordon Gallup Jr. of Albany College in New York. And many researchers say there’s good evidence for passing the test in bottlenose dolphins, Asian elephants and European magpies, although Gallup is skeptical of those results.

The test exposes animals to a mirror and looks for reactions that indicate some recognition of themselves. For example, do the animals do unusual things to see if the image copies them?

Passing the test A cleaner wrasse in an aquarium appears to interact with its reflection.

suggests an animal can “become the object of its own attention,” and if it does, it should be able to use its own experience to infer what others know, want or intend to do, said Gallup, who did not participate in the fish study.

The new paper released Thursday by PLOS Biology subjected up to 10 fish to various parts of the test. Alex Jordan, who’s at the Max Planck Institute for Ornithology in Konstanz, Germany, and colleagues observed a reef-dwelling species called the cleaner wrasse doing odd behaviors like swimming upside down by the mirror. When

four fish were injected with a tag that left a visible brown mark under their throats, three scraped that part of their bodies against a rock or the sandy bottom of the tank, as if trying to remove it.

But Jordan, Gallup and some other experts aren’t convinced.

“To explore selfawareness further we should stop looking at responses to the mirror as the litmus test” and turn to other means of evaluation, said Frans de Waal, an expert on ape and monkey behavior at Emory University’s Yerkes National Primate Research Center in Atlanta.