Delay of gratification is defined as a cognitive and motivational mechanism that leads to the choice of a later or more distant reward when a person is confronted with an immediate or close reward. Delay of gratification is one of the most important regulatory processes determining successful self-regulation. Neuroimaging studies proved that the ability to delay has biological foundations, and high-delayers revealed much better inhibitory control; i.e. a more active prefrontal cortex in tasks demanding inhibition, than low-delayers. Delay of gratification measured in childhood predicts life outcomes, because it assesses the ability to self-regulate, rather than intelligence.