Machine learning models are trained on data. So anything that falls outside of that data is considered an “outlier”. When a researcher tested an AI model for autonomous vehicles, she showed herself footage of a friend who liked to roll backwards on a wheelchair. These models then chose to run over the friend. On later, more sophisticated models that were “trained to recognize people in wheelchairs”, the models ran over her friend with “greater confidence”, because they assumed that all wheelchair users would always be moving forward rather than backwards.