A few studies have asserted that the whole thing doesn’t exist. In
one study,
David Hanson of Hanson Robotics, in Plano, Texas, and his colleagues showed participants images of two different robots that were animated to simulate human-like facial expressions. The survey simply asked the participants what they thought of the experience.
The vast majority (73%) liked the human-like robots. In fact, not one person stated that these robots disturbed them.
Hanson and his team then showed the participants a continuum of images, starting with a picture of
Princess Jasmine taken from the Disney movie Aladdin. Over the course of six images, Jasmine’s face slowly morphed into that of actress
Jennifer Love Hewitt. The idea of these facial progression studies is to try to observe the dip in likeability that Mori predicted between an obviously cartoon image and an obviously human one. The participants were asked to rank the acceptability of each picture in the series. But, again, rather than see a dip in the scores in the middle of the range – as the uncanny valley would predict – none of the images seemed to bother anyone.
Why this happened isn’t clear, and not everyone thinks Hanson’s experiment is robust. Many other studies have shown the opposite. For example,
Edward Schneider’s lab at SUNY Potsdam in New York collected 75 existing characters from video games and animation, including Hello Kitty, Mickey Mouse, Snoopy and Lara Croft. They asked participants how human and how attractive (or repulsive) they perceived each character to be. In this case, the researchers did find a dip in likeability in the middle of the series, roughly where the ogres from World of Warcraft sit.
Moreover, a team lead by Karl MacDorman at Indiana University conducted an experiment similar to Hanson’s, using a progression of images in which a robot face slowly morphs into a human one. They, too, found a U-shaped dip in likeability in the middle of their 11-image series.
However, among the labs that have observed the uncanny valley, there is strong debate about its shape.
Christoph Bartneck, a robotics researcher at Canterbury University in New Zealand says that, based on his studies,
a valley might be the wrong geological metaphor altogether. "As far as we can tell,” he says, "it looks more like a cliff." Essentially, he says, at the point where robots achieve extreme human-likeness, but remain discernibly un-human, their likeability plummets. And people only start to like them again when they become so human-like that they escape detection.
To make things even more complicated, there’s nothing that proves the uncanny valley reflects gradations of the same reaction. It could be a handful of reactions to different aspects of having a varying degree of human-likeness. When MacDorman showed his subjects videos of many different robots, the responses followed no clear pattern. "The results do not indicate a single uncanny valley for a particular range of human-likeness," MacDorman’s wrote in the paper.
"Rather, they suggest that human-likeness is only one of perhaps many factors influencing the extent to which a robot is perceived as being strange, familiar, or eerie."
Basic instincts
Questions about what reaction (or reactions) cause the uncanny valley (or, indeed, the uncanny cliff) quickly lead to other questions about why we react at all.
There are a few explanations that might account for our strange aversion to humanoid robots. One is that not being able to tell whether something is human or not can be a deeply unsettling feeling in itself. Artists and directors take advantage of this all the time for dramatic effect. The dread that viewers feel while trying to figure out who is a zombie, or Cylon, or alien might be the very same dread they feel when faced with a very realistic robot.
Another explanation focuses on the disconnect between how realistic something looks, and how well it moves.
There's always been a lag time between how quickly designers can make things look like people, and how quickly engineers can make them move like us. If a figure that you thought was human started to move jerkily, you would recoil. Similarly, if you were to shake a robot’s hand while expecting a human touch, but instead felt cold rubber, you would be caught of guard. An unexpected break in humanness can be an unpleasant shock, one that sets off fearful and distrustful instincts. "Whenever we see something move, and we're not familiar with the mechanism of movement,
it grabs our attention," says Andrew Olney, a psychologist at the University of Memphis who works on designing intelligent robots. "If your coffee cup started slowly moving across the table, that would kind of freak you out a bit."
Finally, a third theory turns to evolution.
It suggests that if a robot looks like a human, but moves unnaturally, our brains subconsciously classify what we're seeing as someone with a disease. This is the same explanation proposed for most feelings of disgust. When we stand near something like faeces, rotting flesh, or a jerking robot, we experience a sudden urge to get away from it so as to avoid catching the infections it may harbour. Some preliminary research in rhesus monkeys suggests that these animals share an uncanny valley-like response, indicating that they have perhaps adapted to the same evolutionary pressure in the same way as us.
Ultimate challenge
We are, of course, becoming more accustomed to robots and avatars in everyday life. Between games like
Last of Us and movies like
Avatar, we see computer-generated images of people all the time. Mori's original examples of uncanny objects, like a wooden prosthetic hand, probably wouldn't raise an eyebrow today because they are so obviously fake.
Final Fantasy no longer triggers unsettling feelings among younger viewers, who are used to games like Crysis and Witcher 2. The shift in expectations has been going on all along – and might well continue until technology is good enough to fool us.
This trend sets up a roboticist’s ultimate challenge: to be the first person to build a robot that is indistinguishably human to other humans. It is a challenge that Hiroshi Ishiguro, one of the world’s leading humanoid roboticists, believes he will one day meet. Some of his humanoid robots already interact with people, and some robot designers treat them as if they were human.
When one roboticist named Peter Kahn visited Karl MacDorman’s human-computer interaction lab at Indiana University and wanted to take apart Ishiguro’s Repliee Q1Expo, a petite Japanese humanoid-woman in a pink blazer, he first turned to his wife and asked, “May I touch her?”
But not everyone is convinced that we'll engineer our way out of the uncanny valley, or that it is a good thing if we do. While what makes us uncomfortable is likely to shift, the presence of discomfort won't, they argue. Potentially, it could get worse.
"You can imagine cases, for example, maybe 50 years down the road, someone might be in a relationship with an android and not know it," says MacDorman. “But if there were an accident and some of the mechanical underpinnings are exposed, that would be uncanny. It would be uncanny in a different way.”
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