Contour Bias And The Uncanny Valley: Anthropomorphic Forms Part II

Human beings are programmed to like things similar to themselves. When something looks and acts like us, we tend to be biased in its favor. The thing need not be human. When inanimate objects take on human appearance, act like humans, or otherwise take on human characteristics and qualities, we can’t help but feel more of a connection to them.

Mushroom drawing exhibiting anthropomorphic form

However there’s a limit to how much an object can look and act like us before we feel the opposite effect. When a thing looks too much like us while being clearly artificial we can feel revulsion toward that object. Still the use of anthropomorphic forms can be a great way to convey qualities about a design element and make an emotional connection with your audience.

Last week we looked at the different types of anthropomorphic forms and how and why you might use them in a design. This week we’ll take a look at contour bias which can give cues for how to design your forms to communicate different kinds of messages. We’ll also look at the uncanny valley, which tells us to be careful about how realistic we make out anthropomorphic forms and why abstract is probably the better way to go.

Sharp curves ahead road sign

Contour Bias

Contour bias is a tendency to favor objects with curved contours over objects with sharp angles or points. If you think about it on a subconscious level this makes a lot of sense. Sharp and pointed objects can be used to stab and cut. They are potential threats to us physically. They lead to an subconscious processing of fear in a region of the brain called the amygdala.

In contrast softer curves aren’t seen as a threat and so are preferred. They aren’t going to hurt us. There is no fear associated with them, no defense mechanism activated when viewing them. We like curves.

Think of most road signs. Often they exist to alert us of potential danger. They need to grab out attention. You may notice most road signs are angular. Take the image above warning of steep grades and sharp curves. In fact think about how when a curve becomes dangerous we call it a sharp curve.

The angularity or lack of angularity of features in an element or object influences how that element or object is perceived. Studies have shown that subjects strongly prefer rounded objects over angular ones (PDF). A round watch is preferred to a square one for example.

Studies also show the degree of amygdala activation is directly proportional to the amount of sharpness or angularity an object has. The sharper it is, the more we fear it. Consequently there’s an inverse proportional relationship in preference. The less sharpness or angularity the greater the preference. These effects have been observed in both men and women suggesting that there is some kind of innate contour bias in all human beings.

Labradour puppy 'Nala'

There’s an important caveat. The above holds true for emotionally neutral objects, but not necessarily for objects that carry emotion. Consider a puppy. Puppies are cute and adorable. We melt in their presence. Who doesn’t love a puppy? If you draw an angular puppy it’s unlikely that viewers will fear it. Our positive emotional associations with a puppy outweigh our fear of sharp, angular objects.

Additionally studies have shown there is a deeper processing in the brain when viewing sharp and pointed forms. Again this makes sense given the idea of their being a potential threat. We need to pay more attention when sharp objects are around. This suggests we find them more interesting and that they attract our attention quicker.

Contour bias isn’t about avoiding angularity, sharpness, and pointedness. It’s about understanding how we perceive round objects in contrast to sharp objects. And again it’s important to remember the bias is strongest in emotionally neutral objects and designs.

Still it gives us some practical guidelines

  • use contoured forms to make a more positive first impression and to set a positive frame.
  • use sharp, angular, and pointed forms to attract attention, interest, and to provoke thought.

Both types of forms can and should be used in designs where appropriate. Don’t fear using sharp objects because you…well because you fear them. Use them in places where you want to attract the viewer’s attention and use rounded forms where you need to set a positive mood.

The Uncanny Valley

In 1970 roboticist, Mashiro Mori, coined the phrase the uncanny valley, in response to an observation that as robots approached humans in look and actions, there was a considerable drop off in our preference for them.

The theory is that as robots are made more human-like our emotional appeal to them increases until a certain point is reached, where there is a strong negative emotional response. If we continue past this point and make the robot more and more realistic we again increase the emotional appeal. This sharp decline is easily seen in the graph below and makes it easy to understand why the concept is referred to as the “uncanny valley.”

Graph of The Uncanny Valley

Researchers at Princeton have even shown the uncanny valley is not solely limited to human beings. They found that macaque monkeys also fall into the valley when looking at computer-generated images of monkeys that are similar, but not quite perfect representations.

We can generalize the uncanny valley to say that anthropomorphic forms are appealing when they are dissimilar or identical to human being beings, but unappealing when they are very similar to, though just short of human beings. When the form is close, but not quite identical to a healthy human being, the form tends to be distinctly unappealing.

For example take store mannequins or computer generated rendering of people. Both feel off when they’re close to looking like us, but don’t quite get there. When they’re abstracted some so they appear similar, but not too similar we find them easier to look at and watch.

Train conductor from ThePolar Express

A common example of the uncanny valley in action is the movie, The Polar Express, which used a high degree of realism in the CG characters. While the effect was impressive, it was also somewhat off putting. We have these characters, which are very similar to us in their human-like qualities, but we know they’re artificial. We’re in the uncanny valley watching the movie.

Here’s a quote from a review on the movie’s listing at IMDB, which shows how some felt watching the movie

This movie is void of any emotion, any soul

The reviewer, while not necessarily aware of the phrase, is describing the uncanny valley in action.

Avatar: Jake Scully

On the other hand a movie like Avatar may have pushed through to the other side of the valley in its use of animation and 3D, which may help explain part of the movie’s success. It’s also possible that because the characters aren’t human there was never going to be an uncanny valley where they were concerned.

Now consider store mannequins. Retail stores often think they should be creating more realistic mannequins. However the uncanny valley suggests they should actually be more abstract if they want us to find the mannequins and by consequence the clothes on the mannequins more appealing.

The next time you’re out shopping take a look at the store mannequins and ask your self how they make you feel. Are they realistic looking? More abstract in form? Which do you prefer?

Abstract mannequin and realistic mannequin in the uncanny valley

Mannequin in a window, Downtown St. Paul. Mannequin 12

Some dispute the existence of the uncanny valley as unfamiliarity with artificial and rendered likeness, but recent empirical evidence suggests the phenomenon is real. It’s possibly the result of a subconscious avoidance of people who are sick or dead. Once again a self protection mechanism.

When the object is close, but not quite, we see how it fails to resemble us. The negative is emphasized. When it’s somewhat less similar we see the similarities between us and it and an emotional appeal is created. The positive is emphasized.

The uncanny valley can be triggered by:

  • abnormally proportioned or positioned facial features
  • asymmetry of facial features
  • subtleties of eye movement
  • unnatural skin complexion
  • jerky or unnatural movements

The strength of the negative reaction corresponds to the fidelity of the likeness. When the object is highly realistic and identified as artificial it evokes a stronger negative feeling than if the object was less realistic. This suggests we may want to use more abstract anthropomorphic forms in our designs.

Robots at Next Fest at the Los Angeles Convention Center

While generally observed most by animators and roboticists (as the negative reaction is more sensitive to motion than appearance), visual designers should keep the ideas of the uncanny valley in mind when working with anthropomorphic forms. You probably want to err on the side of the abstract in order to gain the most acceptance for your forms, to create the strongest positive emotional response.

The Uncanny Valley and Interface Design

A few years ago Bill Higgins posted, the Uncanny Valley of user interface design, in which he states

We must ensure that we design our applications to remain consistent with the environment in which our software runs. In more concrete terms: a Windows application should look and feel like a Windows application, a Mac application should look and feel like a Mac application, and a web application should look and feel like a web application.

The idea further abstracts the idea of the uncanny valley as one where object and environment need not be anthropomorphic and human. It’s important to remember that the principle only holds for forms approaching human-like qualities, but it makes intuitive sense that designing an element consistent with its environment is a good thing.

This is design unity. This is creating harmony between design elements so all elements are working to convey the same central message or messages. It’s how a design becomes something greater than the sum of all its elements.

Richard Monson- Haefel challenges Higgins assertion stating the uncanny valley theory doesn’t apply to desktop UI. He’s right to challenge, since again this is a phenomenon that relates to objects approaching human beings. However I’ve always noticed a preference in myself to favor software where the interface matches the aesthetics of the underlying operating system or at least matches the aesthetic of the majority of programs developed for the OS.

Perhaps it’s not the uncanny valley at work in interface design, but something is at work. I can’t say that my degree of liking an application fell off when it didn’t quite match the operating system. I will likely pay more attention though having now researched the topic.

Thinking about the uncanny valley in relation to user interface and website design is definitely something to consider even if the concept is meant to apply to human-like qualities and may not be applicable to interfaces.

Additional Resources

Here are a few more resources I collected in researching this article.

Boy in The Polar Express


Due to survival and preservation instincts human beings are prone to fear sharp and pointed objects. By contrast we’re prone to like softer more rounded objects and this tendency is known as contour bias.

Through the use of contours we can help get our audience on our side from the start. We can create designs that appeal to them on an unconscious level. We should’t however avoid the use of sharp objects. Angular lines are an important element in design. Our survival instinct makes us take notice of them and they can add interest to a design.

Remember that contour bias has the greatest impact when the element in question is emotionally neutral.

As mentioned last week, anthropomorphic forms can be a great way to make an emotional connection with your audience. Again we like things that remind us of us.

However when moving from the abstract form to the more realistic form there’s a point where we don’t like what we see. There’s a point where we feel a negative reaction to the object that tries to be like us, but doesn’t quite get there. We’re left with an eerie feeling we don’t much care for.

This uncanny valley can be triggered by a variety of things, but they all come down to being close, but not quite. These triggers help emphasize how the element is not like us more than they emphasize how it is like us.

Your best bet is to favor the abstract anthropomorphic form or to make sure you push through the valley to achieve something truly realistic. Since we’re likely trying to be subtle in our designs lean toward the abstract and save the realism for photographs.

I hope these two posts have helped you understand anthropomorphic forms and why and how to use them in your designs. Keep the ideas of the waist-to-hip ratio and contour bias in mind when creating anthropomorphic forms, though I don’t think you need to do the math. Remember that if you get too close to human without actually being human your forms will have an opposite effect than what you desire.

Avatar: Neytiri

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One comment

  1. “In fact think about how when a curve becomes dangerous we call it a sharp curve.”
    I think that’s probably because of the angle being closer to a sharp angle, not necessarilly because we associate sharpness with danger.

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