"Yotaro is a robot with which you can experience physical contact just like with a real baby and reproduce the same feelings," said Hiroki Kunimura of Tsukuba University's robotics and behavioral sciences lab north of Tokyo.
The baby changes its facial expressions and moves its arms and legs when different parts of its face and body are touched. Physical contact is detected by sensors, and Yotaro's mood changes based on the frequency of touches. Yotaro also simulates a runny nose, with the help of a water pump that releases body-temperature droplets of water through the nostrils.
"We decided on an infant that has not yet learnt to talk because the feelings generated towards a newborn will be the same for everyone, and because interaction is less complicated than if we had made it talk."
Japan is already famous for highly sophisticated robots, from Honda's humanoid Asimo to pancake-flipping chef Motoman to Paro the fluffy robot seal that helps ease loneliness among the elderly.
The pretty humanoid, which boasts 42 motion motors programmed to mimic the movements of flesh-and-blood fashion models, was unveiled last year ahead of Tokyo Fashion Week.
The world last year also got a glimpse of Japan's first child-robot, the CB2, with a so-called "biomimetic" body designed to learn and interact just like a human infant, mimicking a mother-baby relationship. Elsewhere the University of Osaka last week unveiled a robot that mimics a crawling baby, part of a research project to examine the process by which a human being acquires the skills to move and speak.
The 50-centimetre (20-inch), 3.5-kilogram (7.7-pound) M3-neony has a body similar to that of a newborn. It is equipped with 22 motors, 90 tactile sensors and microphones placed near the eyes and ears.
Japan has the world's longest average life expectancy -- 79 years for men and 86 years for women -- and one of the lowest birth rates, meaning its population is headed for a steep decline. The Tsukuba students hope Yotaro may help Japanese want babies to revitalise a country where more than a fifth of the population is aged 65 or older. By 2050, that figure is expected to rise to 40 percent.