There's the famous marshmallow experiments that have been done with human children where they learn that there's a marshmallow put in front of them on a plate, but if they don't eat this marshmallow for a certain number of minutes, they'll get a second marshmallow as well.
Hay los famosos experimentos de malvaviscos que han sido realizado con niños humanos donde descubren que hay un malvavisco delante ellos en un plato pero si no comen este malvavisco por tal número de minutos, recibirán además un segundo malvavisco.