Sciam article on the effects of believing (or having been recently exposed to the idea that) free will is in some sense illusory.
Equally disturbing for social cohesion, diminished belief in free will also seems to release urges to harm others. One of the admittedly odd ways that psychologists measure aggression in the laboratory is by giving people the opportunity to add hot sauce or salsa to a snack that they know will be served to someone who hates spicy food. Roy F. Baumeister of Florida State University and his colleagues asked a group of volunteers to read arguments for or against the existence of free will before preparing plates of tortilla chips and clearly labeled hot salsa for another volunteer who had rebuffed each group member earlier, refusing to work together with that person. This same aloof individual, the subjects knew full well, was not a fan of spiciness, and the person would have to eat everything that was handed out. Those who had read texts doubting free will’s existence used nearly double the amount of salsa.