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25936Monkey See, Monkey Speak: Facial Expressions as a Guide to Speech

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  • Ian Pitchford
    Jul 1, 2003
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      New York Times
      July 1, 2003
      Monkey See, Monkey Speak: Facial Expressions as a Guide to Speech

      Scientists have long known that there is more to speech perception than meets
      the ear. Humans, even infants who cannot yet speak, pick up visual cues from
      the movement of the lips and other parts of the face to help understand what it
      is they are hearing.

      Now there is evidence that this ability may go back a long way. Researchers in
      Germany say they have found that rhesus monkeys can also combine visual and
      auditory information to perceive vocal signals, suggesting that the ability had
      some kind of evolutionary precursor before humans and other primates diverged
      millions of years ago.

      The researchers, Dr. Asif A. Ghazanfar and Dr. Nikos K. Logothetis of the Max
      Planck Institute for Biological Cybernetics in Tübingen, tested monkeys by
      showing them side-by-side video images of another monkey making two sounds,
      while playing a soundtrack of just one of the sounds. Time after time, the test
      monkeys were able to match the sound with the correct video image. The research
      was reported in the current issue of the journal Nature.

      "We know that for human speech perception, when you communicate one on one with
      someone, you glean a lot of information not only from sound, but from facial
      expressions," Dr. Ghazanfar said. But with other animals, he said, "we didn't
      know if perceivers use that multimodal means of perception as well."

      The experiment is very similar to the kind that has been done with infants as
      young as 18 to 20 weeks to show that even at a prelinguistic age, they use
      facial expressions as an aid to perceiving speech.

      But Dr. Ghazanfar said such studies had not been done on other animals,
      particularly closely related primates.

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