People were given a page from a technical manual and told to cross out every "e" they could find. Half of the group were given more difficult rules: don’t cross out any "e" that appears next to another vowel, or that is separated from another vowel by only one letter. Their page of text had also been lightened to make it more difficult to read.
eeee eeee
eeee eeee
Next, people were told to watch a video until they felt they could answer some questions about the content. The video had been chosen because it was extremely boring. Each person was given a box with a button on it. Half of the people were told to push the button when they wanted to stop watching the video. The other half were told to hold down the button while watching the video, and release it when they wanted to stop.
Release to Stop
Press to Stop
When confronted with the need to make an active choice (press the button) to end the boring video, people who had worn their willpower out trying to find the "e" that didn’t violate the difficult rules spent almost a full minute longer watching than did those same ego depleted people when all they had to do was lift their finger off the button (125 seconds vs. 71 seconds).
Release to Stop
71 sec
vs.
Press to Stop
125 sec
People who had the easier "e" task of stopped the video about as quickly in either condition - whether it required an active or a passive choice.