Would you prefer your robot helper of the future to look like a machine, like a human or something in between? The answer, it turns out, likely depends on both how old you are and what task that robot is assigned to do.

Researchers recruited 64 people, half between the ages of 18 to 23 and the other between the ages of 75 to 85, and asked them to judge a series of would-be robot mugshots. The line up included four human faces, four mixed cyborg-human faces and four robot faces that are currently in development (those of Nexi, Kobian, Pearl and Nao). When asked which of the faces the participants would most desire their personal assistant to have, the younger group leaned in favor of the classic robot look, whereas more than half of the older crowd preferred the human-in-appearance robot. Very few of the participants chose the robot-human hybrids. NBC News elaborates on the complicated psychology of man and machine:

The human likeness was a turnoff for a few of the younger lot (perhaps because they’d seen “Battlestar Galactica” all too recently?). Those who picked robotic faces expected that human-looking machines would be victim to human weaknesses: “Humans lie, but machines don’t,” is how one subject explained their preference to Prakash.

However, when the researchers recontextualized the scenario by picking a new job for the robot, the participants likewise shifted their opinions of what the robot should look like. If the robot would be cleaning a house or performing other mundane tasks, they largely agreed that it should look like a machine. On the other hand, if it was being entrusted to make serious decisions, help a person socially or dole out advice, they felt that it should look human because it would seem “smarter,” NBC reports.

Finally, nearly all the participants agreed that a robot that helps them with intimate tasks such as bathing should most definitely not look human. ”Sometimes personal care can get pretty involved,” the researchers said in a statement. “Many participants said they would rather have an impersonal looking creature caring for their personal needs.”

More from Smithsonian.com:

Robots Inspired by Biology

My Robot Helper of Tomorrow