We may have plenty of ideas about what a robot should look like — make something too machine-like, and we may not be able to connect with it; make a humanoid robot, and we might become too attached or view the result as creepy. According to new research, however, these preferences are far from uniform: they depend on both our age and what the robot would be doing. Georgia Tech graduate student Akanksha Prakash and professor Wendy Rogers showed groups of college-age students and senior citizens pictures of several robots. Some were real, like Nexi. Others were artistic renderings of cyborgs. Some were simply pictures of people. Which one, Prakash and Rogers asked, was the participant's ideal robot?

When participants were just asked to pick a favorite, the groups split down age lines, as NBC News reports. The older group wanted human robots, while the younger subjects slightly preferred present-day robots, which may have human faces but are indisputably metal and plastic. "Humans lie, but machines don't," said one test subject. Cyborgs, it seemed, were the worst of both worlds, as no group preferred them.

"Humans lie, but machines don't."

Asking participants what robot they would pick for a specific test, however, produced a new set of preferences. For menial tasks like vacuuming, mechanical-looking robots were best, NBC reports. As tasks got more nuanced, though, people started to prefer humans. A robot that would help people invest, the younger group said, should look smart — and therefore human, despite their previous preferences. In other cases, this kind of reasoning could lead participants in completely opposite directions. When asked what a robot that helped with personal care — bathing, for instance — some people wanted an entirely machinelike robot, saying it wouldn't make them feel like they were being watched. But others wanted something human, trustworthy, and empathetic.

While this study focused on different levels of "humanity" in robots, other studies have found that this isn't all that people look at when selecting their ideal helper for a task. In one study, people were given a pair of similar robots, of which one appeared more masculine and the other more feminine (with long hair and upturned lips), then asked which tasks they were more suited for. Despite being nearly identical, participants essentially broke the two robots' tasks down based on stereotypes. This research, however, shows that our relationship is more complex than simply looking for a pretty face.