Robots - the more human the better, study finds

Imitation is not just the best form of flattery - it's also good interface design. A study shows that talking computers that copy a user's unique vocal inflections seem easier to use.

The researchers think that a key component of machine likeability is the ability to mirror the 'music' - the rhythm and pitch - of a user's speech.

This finding stemmed from an experiment conducted by Japanese researcher Noriko Suzuki's team at ATR Media Information Science Laboratories in Kyoto, reported scientific journal New Scientist.

According to the report, the researchers looked at how social bonds develop between people. When we sense that a person is making an effort to copy the way that we speak, we tend to like that person more, they believed.

The group asked volunteers to work with an animated computer character that had the linguistic capabilities of a one-year-old child, the report said. The participants were told to make toy animals out of blocks on the computer screen and to say the names of these animals to the character.

The report said the character would in return hum sounds that mimicked the volunteers' speech in rhythm, intonation, loudness and pitch.

The users were then asked to rate the character on attributes such as cooperation, learning ability, task-achievement, comfort, friendliness and sympathy.

Results showed that the animated character scored highest on all counts when it mimicked 80 per cent of a volunteer's voice - proving that the advice "It's not just what you say but how you say it" also counts for machines, according to the report.

"The user felt some kind of friendly emotion from the computer, even though it was just copying the stresses and intonation of their own voices," Suzuki said. The research team said the character did not imitate the volunteers' voices fully, but created the impression that it had free will and thus was more human and more loveable.

Suzuki said in the report that this revelation can help forge closer bonds between people and machines. "Sometimes people are afraid of robots," he said. "But if robot voice patterns are improved, people may warm up to them."

That opinion is shared by Timothy Bickmore, an expert on human-computer interaction at the Massachusetts Institute of Technology.

Bickmore said in the report that such mimicry can indeed help build rapport between humans and computerised characters or robots. He added that this finding could be applied in areas such as entertainment, computer gaming and toys.

The history of personal computing is filled with attempts to make daunting interfaces more likeable through the use of human-like avatars or characters such as Microsoft's Office paperclip Clippy or its Bob operating system.

Winston Chai writes for CNET News.com.