There's a trend of robots becoming more human-like in appearance and coming more in contact with humans," Levy said. "At first robots were used impersonally, in factories where they helped build automobiles, for instance. Then they were used in offices to deliver mail, or to show visitors around museums, or in homes as vacuum cleaners, such as with the Roomba. Now you have robot toys, like Sony's Aibo robot dog, or Tickle Me Elmos, or digital pets like Tamagotchis.