Replaced by

Sherief Abdallah, Jean-François Bonnefon, Manuel Cebrian, Jacob W. Crandall, Fatimah Ishowo-Oloko, Mayada Oudah, Iyad Rahwan, Azim Shariff, and Tennom, “Cooperating with Machines”, Nature Communications, vol. 9, n. 233, January 2018.