Curious George Can "Name That Tune"

University of Texas Health Science Center at Houston psychologist Anthony A. Wright has proven that Rhesus monkeys hear music and other sounds much like humans do. In fact, the animals are able to identify the same melodies played at different octaves from dissimilar melodies played in the same key.

"While there have been other experiments involving the musical perception of animals, no one has been able to show this kind of perception until now," said Wright, a professor in the Department of Neurobiology and Anatomy at The University of Texas Medical School at Houston. "The animals in my study were able to tell me whether any two sounds, including musical passages, were the same or different."

Wright, aided by research assistant Jacquelyne J. Rivera, used music such as children's songs, as well as animal sounds, and environmental noises such as horns honking and construction sounds. The monkeys participating in the study listened to pairs of sounds, then identified whether they believed the sounds were different or the same by touching different speakers. Correct responses were rewarded with orange juice.

Special tests of music perception were also conducted. They explored whether melodies would be perceived as the same even if they had been shifted by an octave or more.

"On these tests, we rewarded the animals whether the correct response was 'similar' or 'different,' because we didn't want to have the monkeys trained to believe that only one answer would result in a reward," Wright said.

The monkeys reliably identified the melodies of two songs, "Happy Birthday to You," and "Yankee Doodle Dandy", even when they were separated by as many as two octaves. However, when the two musical passages were random notes, they were not judged to be the same for similar octave separations.

The difference, Wright said, is the identification of "good" music.

"Childhood songs are what we call musically pleasing-what we determine to be 'good' music. The random notes are deemed 'bad' music," he said. "Good tunes are ones we remember. We hum them to ourselves. This appears to be the same for monkeys, even if they haven't heard these tunes before. For the monkey to determine whether a melody played in two different octaves is the same requires that the melody be memorable, just like it is for us. It is the same tune for monkeys as it is for us, provided the key is the same."

Supporting these conclusions were tests of half-octave shifts, which did not result in same-tune perception by the monkeys. Individual notes from the childhood songs, when tested with octave shifts, also were not perceived to be the same by the animals. Wright said this is important, because deleting just one note from a melody destroys it.

Wright's research, supported in part by the National Institutes of Health and published in the Journal of Experimental Psychology: General and reported as the lead article in the most recent Science News, is another important step in discovering which biological and emotional characteristics people and animals share. Wright's future plans include testing the memory and abstract concept learning capabilities of various animals.

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©2006 Texas Medical Center

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