uh... because it's an action that was not previously being done that (hypothetically) is now being done.
http://www.washingtonpost.com/wp-dyn/content/article/2007/12/13/AR2007121301303.html
Any evidence to the contrary?
And while the latter is certain to have happened at some point, it seems flatly stupid to think it's the standard.
Really? So how much money would you bet that
1) The verbal portion of the brain consistently comes up with justifications independently of the actual mechanisms which motivate a person.
2) That people predictably are wrong about how they would act in general, even if they are rewarded or threatened with pain?
And unrelated to the two above
3) That people can be manipulated by entirely random and arbitrary factors such as What was the last number they heard/saw?
After all, you must be fairly confident that what you're saying is true, and not, in fact, a guess made without even trying to look at the literature involved, hm?
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Eh? You Serious? Easy Mode? How Disgusting!
Only Elementary School Kids should play on Easy Mode.