People in London look the most miserable in their selfies while "strong smiles" are found in Sao Paulo and Bangkok, says a researcher involved in setting up a London show about selfies. For its new exhibition Big Bang Data, Somerset House commissioned Selfiecity London, a spotlight on 640 selfies selected out of a total of 152,462 public Instagram images taken in a single week in September in a 5sq km radius around the museum. The show opened on 3 December.

Selfiecity's eight-person lab compiles and analyses selfies from around the world, the five other cities so far being Bangkok, Berlin, Moscow, New York and Sao Paulo. On a touchscreen, visitors to the Selfiecity display can introduce filters and criteria – "people from London over 35" or "very small children" – and observe patterns and trends within that chosen subgroup. Globally, the findings showed that every city was unique in its own way, according to researcher Moritz Stefaner.

People taking selfies in London smiled the least and closed their eyes the most, Stefaner said. By contrast, the highest percentages of "strong smiles" were to be found in Bangkok and Sao Paulo, whereas the ratios in Moscow and New York were significantly lower.

"If we look to Sao Paulo, for instance, we can see that people have quite cheerful faces," he said. "And they tend to tilt their heads quite strongly when taking selfies. And in the software that we built we can find all these patterns. If we jump to London again, faces are much more composed, much more serious and sometimes straight up angry. We don't know why that is, it might be a weather thing, it might be some other cultural difference."

London selfie takers included more older men than elsewhere: the average male was 28 years old, versus 26.3 for other cities. The youngest selfie takers of all were to be found in Bangkok, where the average age for females was 20.3 and males 22.7.

"We use automatic image analysis to detect a few things about the selfies so how angry are people, how calm are they, how much do they smile," Stefaner said. Moscow had by far the highest proportion of female selfie takers – 82% of them were women.