Three Kinds of Human Smiles

By Neuroskeptic | July 28, 2017 2:30 pm

There are three basic types of human smile: “reward”, “affiliative” and “dominance” smiles. That’s according to a new paper by psychologists Magdalena Rychlowska and colleagues.

Here’s the authors’ illustration of the types, as posed by actors:

three_smile_typesReward smiles, the authors say, are used to signal enjoyment:

Reward smiles are displayed to reward the self or other people and to communicate positive experiences or intentions… the reward smile may have evolved from the play face of primates and canids.

Affiliative smiles have a more conciliatory purpose:

Affiliative smiles facilitate social bonding by communicating approachability, acknowledgment, and appeasement and thus may be functionally similar to the silent baredteeth display in chimpanzees that occurs during grooming, sexual solicitation, and submission.

Dominance smiles have a rather darker nature:

Dominance smiles serve to maintain and negotiate social or moral status and are associated with superiority or pride, defiance, derision, and contempt. Unlike reward and affiliative smiles, dominance smiles are assumed to elicit negative feelings in observers. No homologous primate facial expression is known; however, some facial expressions displayed by high-status animal aggressors involve smile components.

This trichotomy of smiles isn’t an entirely new idea, having been proposed by some of the current authors back in 2010. In the new study, Rychlowska et al. studied exactly what makes up these smiles in terms of facial muscle movements.

A group of volunteers were shown 2,400 randomly generated facial expression animations, built using a computer model of the human face. For each random expression, the participants had to say whether it was a reward, affiliative, or dominance smile, or none of the above. All of the expressions were constrained to be somewhat smile-like because they all involved the “Lip Corner Puller” muscle action.

This image shows the muscle movements most characteristic of each smile type:

smiles_FACS

The reward and affiliative smiles were fairly similar, but only the affiliative smile involved keeping the mouth closed and pressing the lips together. This is hard to see in the virtual faces, but can be seen in the actor photos. The dominance smile was very different from the others. In particular, it was a one-sided smile, with only one lip corned pulled up.

Further experiments showed that people were able to correctly tell apart (virtual) smiles of different types, although reward and affiliative smiles were the hardest to distinguish.

The authors conclude on a poetic note, writing that “our results highlight the versatile nature of the human smile, which can be used for multiple social tasks, including love, sympathy, and war.”

This study has a big limitation, however: all of the participants were white American college students, and all the virtual faces were white too. Does the three-smile model apply to other countries and cultural groups around the world? That remains to be seen.

Rychlowska et al. did publish a paper in 2015 that found three main “reasons for smiling” as reported by 726 people from 9 countries. These three factors matched theĀ “reward”, “affiliative” and “dominance” model. However, I don’t think this establishes that people from every country would recognize all three types of smile, nor can we assume that the facial muscle patterns are the same everywhere.

CATEGORIZED UNDER: faces, papers, select, Top Posts
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  • smut clyde

    the reward smile may have evolved from the play face of primates and canids
    Perhaps we have different ancestors.

    • OWilson

      What about knowing smiles, satirical smiles or sarcastic smiles or chagrined smiles, resigned smiles or smiley smiles? :)

      • http://www.facebook.com/Kieseyhow KieSeyHow

        They all seem sub-categorized under one of the three noted in this article. I have looked into this before when researching the psychology of the subconscious. These are more akin to non-verbal communication that our subconscious picks up, rather than the conscious. But, as with most aspects of psychology, one can train to notice them consciously for an element of control over others. The conscious mind is limited in bandwidth, and is unaware of these aspects of human communication for most people.

  • https://llordoftherealm.wordpress.com/ Lord

    These could probably be faked as well.

    • June

      Right!

  • http://stephan-zielinski.com/ Stephan Zielinski

    Dominance smile, AKA “DreamWorks Face”: http://tvtropes.org/pmwiki/pmwiki.php/Main/DreamworksFace

  • Bernard Carroll

    I’ll spend more time observing Donald Trump’s smiles… mostly some variant of dominant/smug/sneering.

  • Erik Bosma

    And when they smile in your face all they want to do is take your place.

  • PLauren

    The ‘Dominance ‘ Smile isn’t a smile at all ; it’s an expression from one who can’t smile .

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      Interestingly Rychlowska et al. did consider whether the dominance smile was truly a smile. They say most people do consider it one, but less so than the other smiles:

      “Fifteen experienced actors encoded the smiles after being
      coached about the appearance of the smiles as indicated by the present findings… participants were significantly more likely than chance to categorize reward, affiliative, and dominance smiles as smiles (estimated probabilities: 98%, 86%, and 69%, respectively). Neutral and disgust facial expressions were not
      categorized as smiles (estimated probabilities: 6% and 2%,
      respectively).”

    • http://www.facebook.com/Kieseyhow KieSeyHow

      It is a smile mostly expressed subconsciously, rather than consciously. like expressions of fear and disgust. It is a subconscious display of dominance, and very useful to learn to spot in business and marketing situations. Also watch for this in situations when you meet strangers, as it may indicate criminal intent.

  • Florida Limey

    What about the “I don’t know WTF you are talking about” smile? And what about the “You’re a f-ing idiot” smile? You know, the ones we all do when listening to or watching the current Dear Leader Of The Free World!

    Interesting article as far as it goes. However, I think Sapiens are a little more complicated than just three variations of lip corner pulling. How are the eyes implicated in smiling, for instance? Life seems replete with characters who smile with their mouths but not with their eyes. Which to believe, mouth corner pulling or eye squints?

  • 31007 – TANSTAAFL

    The Dominance Smile would be better described as a smirk

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Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.

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