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Monkey See, Monkey Recognize
What are animals thinking?

Philosopher Thomas Nagel once asked, "What is it like to be a bat?" Is there "something that it is like to be a bat"? Well, we can try to imagine it. It's dark. We hear a lot of squeaking. We flit. We echolocate up a storm. We feel a little bit . . . batty.

But wait: Does the bat have any sense of its batness? For that matter, what's going on in the mind of a dog, a cow, an ape? Are animals self-aware?

One day in the 1960s, while shaving in front of a mirror, psychologist Gordon Gallup wondered what would happen if you put animals in front of a looking glass. He created what he called the mark test, in which primates already familiar with mirrors and their own reflection were anesthetized and marked with an odorless dye above an eyebrow and on an ear. When the animals woke up, they were shown their reflection in the mirror.

Two species, chimpanzees and orangutans, reacted by touching the dyed spots—evidence, Gallup argued, that these species are self-aware. But Donald Griffin, a biologist at Harvard University, thinks other species are also self-aware, even if they haven't passed the mark test. It doesn't make sense, says Griffin, that chimps and orangs succeed at the test, while other apes, like gorillas, do not. Besides, only 75 percent of adult chimps pass the test. "You'd have to say that some chimps are self-aware and others aren't, which seems a bit ridiculous," Griffin says.

Some researchers contend that dolphins can pass a variation of Gallup's mark test (it's tricky when all the animal has to work with is a flipper). Hardly anything in this field is free of controversy. The stakes are high: At issue is the degree to which humans are different from other creatures. Are we special, or just . . . conceited?

Daniel Povinelli, a cognitive scientist at the University of Louisiana, argues that even small children who pass the mark test lack the kind of self-awareness that older children have. In one of Povinelli's experiments, kids watch a video of someone surreptitiously placing a large, brightly colored sticker on top of their heads just minutes earlier. Most three-year-olds, upon seeing the video, fail to reach up and remove the sticker. They recognize themselves ("That's me!") but don't quite grasp that the sticker is still on their heads ("That sticker's on his head"). And yet most four-year-olds pass the test.

It's hard to say for certain what the mark test really measures. Research on consciousness and self-awareness is dogged by ambiguity. Is it possible that some animals, for example, fail the test simply because they lack the motor skills to touch the mark?

Sometimes in science we get interesting answers—but can't quite decide what it was that we asked.

—Joel Achenbach
    Washington Post Staff Writer

Web Links

Stanford Encyclopedia of Philosophy–Animal Consciousness
Learn about the numerous stances on the hotly debated issue of animal consciousness. This site contains a wealth of bibliographical references as well as additional links.

More Articles by Joel Achenbach
Read some of writer Joel Achenbach's columns for the Washington Post.  

Free World Map

Gallup, Gordon G., Jr. "Chimpanzees: Self-recognition," Science (January 2, 1970), 86-7.
Gallup, Gordon G., Jr. "Can Animals Empathize? Yes," Scientific American Presents (Winter 1998), 66-71.
Griffin, Donald R. Animal Minds, 2nd ed. University of Chicago Press, 2001.
Nagel, Thomas. "What is it like to be a bat?" The Philosophical Review (October 1974), 435-50. Available online at
Povinelli, Daniel J. "Can Animals Empathize? Maybe not," Scientific American Presents (Winter 1998), 67-75.
Povinelli, Daniel J., Keli R. Landau, and Helen K. Perilloux. "Self-Recognition in Young Children Using Delayed Versus Live Feedback: Evidence of a Developmental Asynchrony," Child Development (August 1996), 1540-54.
Reiss, Diana, and Lori Marino. "Mirror Self-Recognition in the Bottlenose Dolphin: A Case of Cognitive Convergence," Proceedings of the National Academy of Sciences (May 8, 2001), 5937-5942. Available online at


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