Smiles perceived as genuine promote cooperation
"A smile gains more friends than a long face.” This Chinese saying has been scientifically validated by researchers of the Max Planck Institute for Evolutionary Biology in Plön and the Toulouse School of Economics in a study involving a behavioural experiment.
The researchers examined whether subjects could induce trust with their smiles and profit from this. The results show that a smile rated as honest and genuine induces trust, and rightly so: on average, those individuals are also more cooperative.
The study shows that genuine smiles are subconsciously produced more frequently when the stakes are higher and the smiler is “honest”. It seems, then, that smiling this way is costly, and the associated effort is made only when worthwhile. Smiles rated as genuine are strong predictors of the trustworthiness of the individual in question.
Smiling is a fundamental component of communication in every human society. Some scientists speculate that it arose during the course of evolution from a gesture of submission such as that observed among apes, when socially inferior animals draw back their lips and bare their teeth as a way of demonstrating their subservience to dominant members of their species. In humans, smiling may have developed as a kind of mimicry in which dominant individuals imitate a submissive gesture in order to signal that they are trustworthy.
It is still unclear, however, whether the human smile is actually a tool for communication or simply an involuntary expression of one's emotional state. Consequently, the Max Planck scientists and their colleagues developed a behavioural experiment to measure the impact of smiling on readiness to cooperate in trust situations. Darwin himself discussed the function of the "Duchenne smile", which is unconscious or involuntary in origin and is considered to be outside voluntary control.
In the experiment, two participants had to cooperate in order to obtain a small sum of four euros in the first wave, or eight euros in a second wave. The trustees (potential recipients) introduced themselves using a predetermined text in short video clips, asking their partners to send the money supplied by the researchers.
Based on the video, the sender then had to decide whether to send the money to the trustee. If the money was sent, the stake was tripled and the trustee could choose whether to return one third or half of the increased stake or simply keep it all, i.e. a maximum of 24 euros, leaving the sender empty-handed.
The scientists started by documenting how the senders and non-participating subjects assessed the video clips. They had to rate the person in the clip for attractiveness, intelligence and trustworthiness and whether they considered his/her smile to be genuine. "The people whose smiles were rated as genuine were also judged to be trustworthy. Senders could actually use the smile as a basis for predicting whether the trustee would share the stakes", explains Manfred Milinski from the Max Planck Institute for Evolutionary Biology.
For the senders, it was worth trusting the trustees who produced genuine smiles, because on average they sent more money back. "This means a smile perceived as genuine is an honest signal that displays a readiness to cooperate. It aims to encourage others to cooperate in situations that require justified trust", says Milinski.
In addition, in games with higher stakes of eight euros, trustees were more likely to produce smiles that were rated as genuine. This suggests that it is easier to produce an honest smile when a greater reward beckons. Since genuine smiles are unconscious in origin and outside voluntary control, it seems that they are costly and involve an effort that is only made unconsciously when it pays – and when the subject really means it. Gifted actors may be able to deliberately produce "genuine" Duchenne smiles. Either way, in the research lab and in daily life, smiling is a frequently used signal that induces trust and promotes cooperation.
Prof. Dr. Manfred Milinski
Max Planck Institute for Evolutionary Biology, Plön
Phone: +49 4522 763-254
Fax: +49 4522 763-310
Centorrino, S., et al.
Honest signaling in trust interactions: smiles rated as genuine induce trust and signal higher earning opportunities
Evolution and Human Behavior 2014, http://dx.doi.org/10.1016/j.evolhumbehav.
Prof. Dr. Manfred Milinski | Max-Planck-Institute
Exploring how herpes simplex virus changes when passed between family members
23.10.2017 | Penn State
Key discoveries offer significant hope of reversing antibiotic resistance
23.10.2017 | University of Bristol
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
23.10.2017 | Event News
17.10.2017 | Event News
10.10.2017 | Event News
23.10.2017 | Physics and Astronomy
23.10.2017 | Earth Sciences
23.10.2017 | Health and Medicine