Cat Or Dog? Sure, you can easily tell the difference. But a machine may not be able to guess on the first try. iStockphoto hide caption

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Joaquin Phoenix stars in the film Her, in which his character falls in love with an operating system. When will artificial intelligence programs like Siri evolve to the point where we'll fall in love with them? Courtesy of Warner Bros. Pictures hide caption

itoggle caption Courtesy of Warner Bros. Pictures

"Child-robot with Biomimetic Body" (or CB2) at Osaka University in Japan in 2009, where the android was slowly developing social skills by interacting with humans and watching their facial expressions, mimicking a mother-baby relationship. Yoshikazu Tsuno/AFP/Getty Images hide caption

itoggle caption Yoshikazu Tsuno/AFP/Getty Images