Twitter algorithm prefers slimmer, younger, light-skinned faces

The pattern held true for images of former US President Barack Obama and senator Mitch McConnnell - and for stock images of businessmen belonging to different ethnicities.

Twitter's own subsequent analysis showed a "4% difference from demographic parity, in favour of white individuals".

And director of software engineering Rumman Chowdhury said Twitter had concluded "how to crop an image is a decision best made by people".

Twitter's algorithm favors younger, slimmer and lighter faces over those who have bigger, older and darker features, a student in Switzerland discovered. Bogdan Kulynych, a graduate student at Switzerland's EFPL university, revealed the algorithm's bias during a competition at a security conference in Las Vegas.