Not sure I totally get this, and from the below quote it seems far less ominous than at first glance. Still, imagine the implications…

“Researchers led by Elizabeth Phelps carried out a conditioning experiment in which 20 volunteers sat in front of a computer screen on which squares of different colours appeared. When blue squares flashed on the screen, they received an electric shock to the wrist.

The next day, the volunteers were shown blue squares again to reactivate the memory. Sensors placed on their skin showed that the images caused the participants to sweat as their stress levels rose.

To erase the memory that linked blue squares with pain, the volunteers were put through “extinction training” which involved flashing blue squares on the screen without the accompanying electrical shocks.”