did this twice -- didn't notice much effect the first time (measurable effect was tiny). When I did it again, I was distracted a bit (mind wandering) and sure e

did this twice -- didn't notice much effect the first time (measurable effect was tiny). When I did it again, I was distracted a bit (mind wandering) and sure enough, when I switched back to the "normal" control, my performance was destroyed. Surprisingly effective.