How we change what others think, feel, believe and do

Smiling

Techniques > Using body language > Smiling

The physiology of the smile | The genuine smile | False smiles | See also

When you smile in a genuine way, it happens using the unconscious brain where emotions are controlled - you are genuinely happy in some way.

Why smile

Smiling has a range of benefits, including:

• You will feel better as endorphins, the brain's natural opiates, are released, as are dopamine and seratonin. (Lane, 2000)
• Release of the stress hormone, cortisol, is reduced, also making you feel better.
• Smiling sends a 'safe' signal, that you are not a threat (unless it's a false smile).
• Smiles are infectious. As people feel good about you, they will smile back. (Hatfield et al, 1992)
• People will find you more attractive (Reis et al, 1990)
• People will trust you more when you smile more. (Schmidt et al, 2012)
• People are less likely to judge you based on such as gender or race.
• Even if you fake it, you'll feel better as your heart rate decreases and you recover from stress quicker. (Kraft and Pressman, 2012)
• You may well even live longer! (Abel and Kruger, 2010)

The physiology of the smile

There are various parts of the face that change when someone smiles:

• The mouth stretches and may well show teeth.
• The muscles that move the cheeks contract, making the eyes crease up and eyebrows dip slightly.
• Lines appear around the eyes.
• The eye cover fold (the bit between the eyebrow and the eyelid) moves downward.
• The end of the eyebrows dip very slightly

The genuine smile

The genuine smile, also known as Duchenne smile indicates real happiness or amusement. In particular it is different from the false smile in the use of the cheeks and the muscles above the eyes (the orbicularis oculi). Eyelids may fold more and the outer ends of the eyebrows may dip.

It is not the entire orbicularis oculi, actually, that is involved, only the outer portion, the orbicularis oculi, pars lateralis.

A genuine smile tends to last for 0.5 to 4 seconds (so believe a quick smile over a longer one). It may be asymmetric and larger on the right side of the face. It may also cover the whole face and so make asymmetry less obvious. Happy expressions tend to be more symmetrical than sad expressions.

Genuine smiles are smooth and natural, quickly or steadily spreading and then gradually fading after the initial maximum stretch.

In the brain, the genuine smile is associated with left frontal EEG activation, which is also associated with positive emotions.

False smiles

False smiles can be remarkably difficult to detect, especially when done by a 'pro'. Yet they are distinctly different.

Watch for excessive symmetry and missing lines around the eyes as the orbicularis oculi are not used, although these can sometimes be forced with strong muscle movement.

Watch for the eye cover fold: it is very difficult to control this. Also the ends of the eyebrows dipping is difficult to fake.

False smilers may lower the jaw to create a D-shaped open-mouthed smile. This is easier to do and pulls attention away from the eyes.

The false smile tends to appear suddenly and disappear suddenly, making it seem less natural. It may be held for too long (more than four seconds).

False smiles may be lop-sided but can also be symmetrical due to the greater cognitive effort involved. When we are paying attention to our muscles, we try to ensure they are all working in the right way.

A false smile does not necessarily mean malevolent deception as people often use false smiles simply to be polite. False smiling is also used to placate other people who may be a threat to us.

Duchenne himself said:

You cannot always exaggerate the significance of this kind of smile, which often is only a simple smile of politeness, just as it can cover a treason. … We politely smile with our lips at the same time as being malcontented or when the soul is sad.

See also

Deceptive body language, Lying

Abel E. and Kruger M. (2010) Smile Intensity in Photographs Predicts Longevity, Psychological Science, 21, 542–544.

Duchenne de Boulogne, G-B. (1862). Me?canisme de la physionomie humaine. Paris: Jules Renouard, Libraire.

Lane, R.D. (2000). Neural correlates of conscious emotional experience. In R.D. Lane & L. Nadel (Eds.), Cognitive neuroscience of emotion (pp. 345–370). New York: Oxford University Press.

Hatfield, E., Cacioppo, J.T., Rapson, R.L. and Clark, M.S. (Ed), (1992). Emotion and social behavior. Review of personality and social psychology, Vol. 14., (pp. 151-177). Thousand Oaks, CA, US: Sage Publications, Inc, xi, 311 pp.

Kraft, T.L. and Pressman, S.D. (2012). Grin and bear it: the influence of manipulated facial expression on the stress response. Psychological Science. 23, 11, 1372-8.

Reis, H.T., Wilson, I.M., Monestere, C., Bernstein, S., Clark, K., Seidl, E., Franco, M., Gioioso, E., Freeman, L. and Radoane, K. (1990). What is smiling is beautiful and good, European Journal of Social Psychology, 20, 3, 259-267

Schmidt, K., Levenstein, R. and Ambadar, Z. (2012). Intensity of smiling and attractiveness as facial signals of trustworthiness in women. Perception and Motor Skills. 114, 3, 964-78.