TORONTO - Can robots and computers take the place of a human being? Two new studies involving research on brain activity in humans provide some food for thought in the evolving debate about interactions between man and machine -- and in both cases, people seem to prefer people.

German scientists used an MRI scanner to see how the brain reacted when subjects thought they were playing a game against four different opponents - a laptop computer, a functional robot with no human shape except for artificial hands, a robot with a humanlike shape and another person.

The 20 participants were also asked about their enjoyment levels after playing the Prisoner's Dilemma Game, which is similar to the Rock Paper Scissors game.

"We were interested in what's going on in the brain when you play an interaction game when you need to think what your opponent is thinking," said Soren Krach, a psychologist in the department of psychiatry at RWTH Aachen University.

In social cognitive neuroscience, the ability to attribute intentions and desires to others is referred to as having a Theory of Mind, according to the study.

"We found out that the activity in the cortical network related to Theory of Mind ... was increasingly engaged the more the opponents exhibited humanlike features," Krach explained.

Before going into the MRI scanner, the subjects played against the laptop, the two robots and the human. Once inside the scanner, they played again, using special video glasses, and they were told which opponent they were playing against at any given time.

Later, they were asked about the interaction.

"They indicated that the more humanlike the opponent was, the more they had perceived fun during the game and they more attributed intelligence to their opponent," Krach said.

The behaviour of the four opponents was randomized.

The study was published Tuesday in the online open-access journal PLoS ONE, along with another study in which neuroscientists looked at the brain's response to piano sonatas played either by a computer or musician.

Stefan Koelsch, a lecturer in psychology who did the study with colleagues at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, said he was interested in exploring how the brain processes music.

While 20 subjects listened to music, they had an electroencephalogram and skin responses were measured, Koelsch said from the University of Sussex where he is based.

"We put headphones on their heads and then they listened to those stimuli, but we did not tell them before the experiment that some stimuli were played by a computer and some were played by a professional pianist," he said.

"Brain response was clearly enhanced when pieces were played by the professional pianist."

He said music affects a lot of "biological parameters," including heartbeat and respiration.

"These are all effects that will eventually become very relevant for music therapeutic applications," he explained.

"It's a field that's beginning to grow."

John Zelek, an associate professor of systems design engineering at the University of Waterloo, said it stands to reason that music played with feeling is going to produce a different response.

"But, I mean, you can program a computer to play with emotion as well," he said, adding that he's seen humans play music without emotion.

As for the computer game study, he said it was interesting that the researchers found a progressive curve.

"The more anthropomorphic the robot is, supposedly the more we're attentive to it."

The findings take him back to the philosophers and questions about what it means to be human, he said.

"Some of my colleagues think that you can actually build out of mechanical parts something that will function like a human," Zelek said. "But there's a part of us that is a machine and there is the other part that is a mind."

He noted that people have a pre-wired disposition to be attracted to human faces.

"In a hospital setting or in a nursing home, if you are using a robot, perhaps it should have an anthropomorphic form. ... where it really matters, and people are cut off from social ties. Perhaps that may provide some benefit."

But his own position is that robots shouldn't be seen; they should be integrated into the environment.

"A good example is a car. A lot of the automobile companies are making them more intelligent, they're putting cameras to assist in parallel parking. You could start calling a car, once it has all these sensors and thinking modules, a robot - but nobody would call a car a robot."

Krach noted that all over the world, robots are increasingly being used for various tasks.

"For example, with elderly people in Japan they use robots to care for them," he said, adding that a future project for him might involve looking at the interaction between robots and people with autism.