Very interesting test.
What would you do? Would you eat or wait?
And you can read more about it, following these links below:
http://www.newyorker.com/reporting/2009/05/18/090518fa_fact_lehrer
http://en.wikipedia.org/wiki/Marshmallow_experiment
This one has a Portuguese translation version…
http://braziliancoffee.wordpress.com/tag/marshmallow-experiment/