In the subsequent experiment Bailenson ran, students stood in the virtual reality version of a forest where they heard wind rustling and birds chirping as they flew past. The participants held a device meant to represent a chain saw, and felt resistance as they passed it back and forth through a tall tree.

The wood cracked, then crashed to the ground with a thunderous boom. The forest fell silent, birds no longer singing.

Before the student left the lab, a woman there knocked over a glass of water on a desk and asked the participant to help her clean it up. The people who had gone through virtual reality used 20 percent less paper than those who had watched a video of a tree being cut down, Bailenson said.

Bailenson said he gets emails months after that experiment from people telling him they can’t walk down the toilet paper aisle of a store without thinking about the falling tree.