Business World

Let’s talk about trust.

Do you trust strangers? 

Look at the following picture, who would you trust among them? Who would you give the keys to your house for a night to, for example? Or your car? 

Photo by August de Richelieu from Pexels

The answer actually doesn’t matter. I don’t even know who these people are, it’s just a random picture that I found on the Internet. 

The fact that you would have answered somehow, however, is actually very interesting per se. Why did you give the answer that you gave? 

Why did you choose that person and not the one to their right (or their left)? 

What happened was that in a very short time, perhaps even less than a second, you formed an idea about the people you were looking at, on the basis of …. well, just their appearance. You managed to form an opinion on the likelihood that they would return your keys in case you lent them to them, even if you’ve never even met them, you don’t know their names, their stories, and so on. Is that choice correct? Who knows. The first impression doesn’t always correspond to the truth. 

The reason why we create these opinions about people even before getting to know them is that we (humans) hate not having data about something. We constantly seek ways to fill those gaps of information, and we do so by retrieving clues from past experiences, for example by attributing the characteristics of people we already know that resemble the unknown ones, creating prejudices and stereotypes, and by building context on our own such that it is sufficiently coherent with what we see. 

As Professor Kahneman explained in “Thinking, Fast and Slow”, our mind is a machine for jumping to conclusions. We continuously assess reality and jump to conclusions about what we cannot know on our own, and the “slow thinking” will eventually take care of rectifying biased and erroneous ideas coming from first impressions, if the resulting image is not coherent enough to be believed. When the available information is scarce, or absent, we adopt the WYSIATI (What You See Is All There Is) method, as Kahneman defined it. 

Going back to our judgment about the folks in the picture above, it has been demonstrated that we can infer two main characteristics from one’s face, namely how dominant and how trustworthy they are (at least in our opinion). We do so from the shape of the face and the facial expression mainly. From these characteristics, we form our evaluation about the competences and personality of the individual in question, but it is often not the case that the external characteristics of someone are actually correlated with how they really are. The evolutionary roots of this ability of ours lie in the fact that we used it to determine rapidly whether the guy in front of us is a threat or not; hopefully, this is not necessary anymore. 

But this is not the only way in which our judgement is often biased. Take for example the ingroup bias, the tendency to prefer the people belonging to our same group, being it determined by shared characteristics or interests or even created at random (see, for example, this article). If we recognize that the people we are trying to judge are part of our same social group, we will automatically treat them better, trust them more and judge them less harshly when they behave in a negative way. When the social group is determined by ethnicity, the ingroup bias becomes ethnocentrism

Sharing economies and trust

Go back to my initial questions now:

“Who would you give the keys to your house for a night to, for example? Or your car?” 

Why would you ever give your house or car’s keys to a complete stranger? Or on the other hand, why would you, as a complete stranger, accept the keys and access to some stranger’s house or car? 

You probably already guessed where I am going with this, but think about Airbnb or Uber. 

The business idea seems simple (you have a good, being it a place to sleep or a car, and you offer it to complete strangers through a common marketplace as a service in exchange for some money), but if you think about it, it is also crazy. Why? Because it is based on trust between two complete strangers, on two sides simultaneously (the provider of the service and the user). 

The marketplaces need to build the trust needed for the two ends of the process to actually end up on the platform and meet. Let’s look closer to one of the biggest players in the field: Airbnb. 

Photo by cottonbro on

Airbnb example: how do they design for trust? 

Airbnb was born almost by chance. The two founders, Joe Gebbia and Brian Chesky, were short of cash and decided to try to rent a place in their apartment in form of an air bed and some breakfast during a period in which hotels were full because of a huge design conference taking place in San Francisco at the time. 

The experience was so good, both for the couple and for their guests, that the two decided to take the idea even further and transform it into a real business. 

They soon realized, however, that asking people to share with strangers the most intimate spaces of theirs, and even post pictures of those rooms on the Internet, was not as easy as it sounds. Also, the people looking for a place to stay were literally accepting to sleep in a complete stranger’s bed. Not exactly what a parent or carer would recommend to their kid. 

The first thing they did was to remove anonymity, so that both guests and hosts had an identity on the platform. The profile pages are filled with personal information, a description of themselves and feedbacks from past trips. Uploading a profile picture is now mandatory and strongly relied upon especially by the guests deciding where to book. 

Providing the information about the individual limits the number of ways in which the users can distort the perception of their host\guest, both for the good and for the bad. 

Example of an empty profile. Source:
Example of a complete profile. Source:

The role of Airbnb itself is also pretty strong in building trust between the two strangers. They act as a protection net in case of negative experiences, such as the host cancelling the reservation of one guest just right before the trip and also take care of the payments, a topic that is too delicate to be left to trust only. The hosts are also taken care of by Airbnb in case they have a negative experience with their guests. 

By keeping high the retention rate of the guests, Airbnb gives another reason for new users to take the leap and trust the service, as positive experiences from an increasing number of users will persuade them to give it a try too. 

The reputation system is another tool that Airbnb uses to encourage trust between guests and hosts. A good reputation is perhaps the best argument for trust. It is therefore an incentive for hosts to make their best to have a positive reputation, and the majority of trips are actually voluntary reviewed by the travellers, meaning that they also recognize the value of their review for the hosts. 

Having a sufficiently high number of reviews has been shown also to reduce the homophily effect, meaning the tendency of guests to look for hosts similar to them. This results in more potential guests for the hosts, and an even more enjoyable experience for the travellers. 

To avoid having biased reviews, due to the fact that both hosts and guests can see each other’s review, a process was put in place, according to which the two reviews are left unpublished for a certain period, so that also bad reviews can be written without fear that the other will retaliate with an even worse comment. 

Airbnb’s case is an excellent example of how knowing about people’s biases can help providing great services and constantly improving experiences for the users. It is also a great proof of what we might be missing when relying only on first impressions and socially taught distrust against others. My suggestion is therefore to constantly tickle your “slower thinking” and keep it active to recognise timely what is due to preconception in judgement and what is actually truthful about others. 


Kahneman, D. (2011). Thinking, fast and slow. Farrar, Straus and Giroux. See our book review here

TED Talk: How Airbnb designs for trust.

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