What, you might ask, could the two possibly have in common? The answer is not so unusual: both have been used to test self-control in humans, and can tell us something about more fundamental aspects of our personalities.
In a now-famous study conducted at Stanford in the 1960's, children were put in separate rooms and given a marshmallow or another treat of their choice by a researcher. The researcher told them that after giving the instructions, he would leave the room for a short while, during which time the child would be left alone. (They would actually be observed by camera during that time.) If the child wanted to eat the treat, there were two official options: 1) ring a bell on the desk, at which point the researcher would come back immediately, and the child could eat the treat, or 2) wait for the researcher to come back on his own, at which point the child would be allowed to eat two treats. Once the researcher left, it became clear that there was a third, unofficial option: just eat the marshmallow.
While this was a fascinating experiment in its own right - in a video from a similar study, you can watch the children trying desperately to resist the third option - the follow-up study about a decade later made it even more interesting. The children who had succeeded in waiting for the two marshmallows turned out to be teenagers who were better adjusted, had fewer problems in school, and also had (wait for it, Princeton) higher SAT scores. In other words, there was a strong correlation between self-control seen at a very young ageand academic success that came years down the road. Another study using fMRI as well as behavioral measures, has linked self-control with intelligence.
Abstinence, in its own way, is the reverse of the "marshmallow." If we are in a situation where it is a live option to engage in sex or other forms of physical intimacy, we have a choice between "now" and "later." In today's culture of excessive self-affirmation, we often hear, "If it feels right, go for it." What this neglects to mention is that something which "feels right" at the time can often feel even better in the future. For those of us waiting for a stable, long-term relationship, such as marriage, to have sex with another person, choosing the "later" option can pay dividends by training us to, in the meantime, live without that instant pleasure. This is by no means masochistic; rather, it is a recognition that the delayed pleasure will be all the more meaningful when it does come.