Most people can fake a genuine "Duchenne" smile

For years, the literature on the psychology of smiling has claimed that fake smiles can be easily and reliably distinguished from genuine smiles by the absence of crinkling around the eyes. The eye crinkling of a supposedly real "Duchenne smile" (named after a Dutch physician with a fondness for electrodes) is caused by activation of the orbicularis oculi muscles, which raises the cheeks. The traditional view is that this muscle is not within voluntary control, unlike the zygomatic major muscle that bends the mouth upwards into a smile. Fake smiles therefore feature the upturned mouth but there's something missing in the eyes, or so it was long claimed.

Doubts first emerged in a 2009 paper, in which Duchenne smiles were produced just as often when participants pretended to be amused, as when they were genuinely amused. Now a research team led by Sarah Gunnery has provided more evidence that undermines the old beliefs about Duchenne smiles being a reliable sign of true positive emotion.

Gunnery and her colleagues had 96 student participants (49 men) pull smiling faces into a camera while role-playing genuine positive emotion (e.g. pleasure at a good exam grade) or while role-playing fake positive emotion (e.g. smiling in response to a gift that's not really liked).

Overall, 28 per cent of the smiles were rated by two experienced coders as Duchenne smiles, with the characteristic crinkling around the eyes. This broke down as 31 per cent for positive situations and 24 per cent in the fake positive situations. When naive viewers rated these smiles, they tended to say the Duchenne smiles were more genuine, but this was largely because eye crinkling tended to go hand in hand with more expressive smiling around the mouth.

Next, the participants were presented with a photograph of a person pulling a Duchenne smile and another showing a "fake" smile with no eye crinkling, and their task was to imitate both. Seventy-one per cent successfully imitated the Duchenne smile, and 69 per cent successfully imitated the fake smile.

These results explode the myth that it's not possible to fake a "genuine" Duchenne smile. They also hint at this being a skill that varies from person to person. It was the same participants who tended to display Duchenne smiles in the various conditions of the experiment. Moreover, these Duchenne participants reported feeling that they'd done a good job in the tasks, and they said they were able to pull fake expressions in their daily lives, all of which suggests they have good insight into their facial abilities.

A weakness of the study is its reliance throughout on staged emotion. While the evidence is clear that many people can fake the Duchenne in neutral conditions (albeit while imagining emotional scenarios), we don't know how easy it is for people to do this under conditions in which they truly are experiencing negative emotion. On the other hand, because there were no explicit instructions in the role-playing tasks to pull a Duchenne smile, nor were there any consequential outcomes to provide extra motivation, the prevalence of the ability to fake Duchenne smiles in neutral conditions may actually have been underestimated.

"Findings from the present study strengthen the argument that people can volitionally activate their cheek raiser muscle and put on a Duchenne smile," Gunnery and her team concluded. "Future research will further investigate individual differences, and will use behavioural outcomes to measure similarities in people who deliberately produce the Duchenne smile."

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Gunnery, S., Hall, J., and Ruben, M. (2012). The Deliberate Duchenne Smile: Individual Differences in Expressive Control Journal of Nonverbal Behavior DOI: 10.1007/s10919-012-0139-4

Post written by Christian Jarrett for the BPS Research Digest.

Are 3D films more psychologically powerful than 2D?

The revival of 3D movies in recent years has prompted much debate among fans and critics. Some say it's gimmicky and too expensive. Others have heralded the return of the technology as the industry's saviour. A key claim in favour of 3D technology is that it makes for a more realistic, immersive experience. But does it really?

Brendan Rooney and his colleagues at University College Dublin showed 8 different movie clips (ranging from 13 to 68 seconds in length) to 27 participants (13 males; average age 27). The gory clips were chosen deliberately for their disgusting content and were taken from Bugs 3D, Friday 13th, Jaws 3-D and Frankenstein.

Each participant watched the clips alone in a mini-cinema on campus featuring a 2.5m x 2.5m screen. Crucially, half the participants viewed the clips in 3D, the others in 2D. To ensure any effects of the 3D format were not due to novelty, all the participants watched an abridged version of Journey to the Centre of the Earth in 3D, at least 24 hours prior to the study proper.

Participants in the 3D condition reported finding the film clips more realistic. They also had a higher heart rate whilst watching the clips compared with participants in the 2D condition. However, there was no difference in amount of skin conductance (another measure of arousal) between the two groups, and no difference in how much they said they enjoyed the clips.

Rooney and his colleagues explain that skin conductance - that is, the skin's sweatiness - is influenced only by the sympathetic nervous system (which triggers the fight or flight response) and not by the parasympathetic nervous system (which calms us down). By contrast, heart rate is influenced by both. This suggests to them that the calming parasympathetic nervous system is less active in viewers of 3D. Why? Well, one theory for how we calm our emotions during films is by reminding ourselves that they're not real. The 3D viewers said they found the viewing experience more realistic and it's possible that this made it more difficult for them to step outside of the experience, leaving their emotional response relatively unchecked. The researchers concede that the causal direction could also run the other way - the 3D viewers raised heart rate could cause them to perceive the experience as more realistic. Most likely the influences are bi-directional.

Is it a good thing that the 3D clips were rated as more realistic and triggered more physiological arousal? The 3D viewers didn't rate the clips as any more enjoyable, but then they only gave these ratings afterwards, which means they were relying on their memory of the experience. Also, they had no baseline to measure their ratings against. Finally, perhaps "enjoyment" is the wrong word when it comes to disgusting movie clips. If the study were repeated with a different genre, perhaps 3D viewers would give higher enjoyment ratings.

Rooney's team stressed that this was an exploratory study and that more research is clearly needed. For now they concluded the "suspension of disbelief is ... assisted by stereoscopic depth, with associated increases in reported perceived apparent reality and in heart-rate ... ".

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Rooney, B., Benson, C., and Hennessy, E. (2012). The apparent reality of movies and emotional arousal: A study using physiological and self-report measures Poetics, 40 (5), 405-422 DOI: 10.1016/j.poetic.2012.07.004

--Further reading--
Right-handers sit to the right of the movie screen to optimise neural processing of the film.

Post written by Christian Jarrett for the BPS Research Digest.