By Christian Jarrett

In the adverts for anti-ageing skin products, everyone is smiling, positively blooming with youthfulness. A canny move by the marketeers you might think – after all, past research has found most of us believe smiling makes people look younger. It’s just that actually, it doesn’t. It makes you look older. That’s according to a new paper in Psychonomic Bulletin and Review that explores an intriguing mismatch between our beliefs and perceptions.

Tzvi Ganel at Ben-Gurion University of the Negev and Melvyn Goodale at the University of Western Ontario began by asking 40 participants (23 women; average age 24) to estimate the age of 35 women and 35 men from photographs of their faces. Participants saw one of two versions of each model’s face, in which they were either smiling or had a neutral expression. On average, the participants rated the faces as older, by about a year, when they saw them smiling compared with when they had a neutral expression.

Despite this, most of the participants (33/40) stated afterwards that they believed smiling makes you look younger. Also, when asked to estimate the average age they’d given for all of the smiling faces they’d viewed and the average age they’d given to the neutral faces, they thought erroneously that they’d rated the smiling faces as younger (presumably in keeping with their belief that smiling makes you look younger).

These new results are consistent with an earlier series of studies by Ganel in which he presented evidence that the ageing effect of smiling (on this occasion of one to two years) is due to the way it increases wrinkles around the eyes. For instance, the ageing effect disappeared when he filtered out eye wrinkles or presented only the lower half of smiling faces.

In the this latest research, Ganel and Goodale followed up with a second experiment in which 42 more participants estimated the ages of faces that were either smiling, neutral or looking surprised. Again, the same person’s face was estimated to be older when smiling compared with when holding a neutral expression. Meanwhile surprised faces were rated as younger than neutral faces, perhaps because the facial expression of surprise acts to smooth out eye wrinkles.

When asked to estimate the average age they’d guessed for smiling, neutral and surprised faces, the participants again mistakenly thought that they’d rated smiling faces as younger than neutral faces. On the other hand, they estimated that they’d given the surprised faces the same average age as the neutral faces, seemingly unaware that they’d actually rated them as younger (presumably due to the lack of any specific beliefs about the effects of a surprised expression on appearance).

“The findings show, for the first time, that people can erroneously believe that smiling makes one appear younger, while at the same time rating smiling faces as older than neutral faces,” the researchers concluded.

Unfortunately, we can’t tell from these findings what part memory plays in the effects, if any. Did participants mistakenly think they’d estimated a younger average age for smiling faces because of the influence of their belief that smiling faces look younger or because they actually remembered the smiling faces as younger? Also, I wonder whether it makes any difference whether a smile is genuine or not – genuine or “Duchenne” smiles are known to involve more crinkling of the muscles around the eyes, so perhaps they have a greater ageing effect than feigned smiles.

These unresolved issues aside, the results suggest that if you’d like to present a more youthful version of yourself on your Twitter or Facebook page, you should delete that grinning selfie and switch for a neutral pose or even a look of surprise. Or you could just dig out an old photo of a younger you!

—The effects of smiling on perceived age defy belief

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest