The Stanford Marshmallow Test was “a study on delayed gratification…in the study, a child was offered a small immediate reward (1 marshmallow) or two small rewards (2 marshmallows) if they waited 15 minutes” (Wikipedia). Children who were able to delay gratification were found to later have better educational outcomes and SAT scores (Wikipedia).
We are conducting a national Marshmallow Test right now. We call it COVID-19. Our case counts look like this right now, according the The New York Times:

Remember in March when we spoke about “flattening the curve”? Flatten the curve meant “wait for 2 marshmallows”. Our current case counts now exceed 150,000 cases a day. For those of you who like to say “but it’s just the flu”, case fatalities on Tuesday were the highest in 6 months.

For those who like to say “it’s not that bad, it’s just the flu”-COVID-19 went from zero to the third leading cause of death in the U.S. in 9 months. More people have died from COVID-19 in 9 months than those U.S. soldiers who died in 20 combined years of Vietnam, Korea and World War 1.
There is some hope. A vaccine should be approved soon. What are we going to do when a vaccine is approved? This is the “how many” question. I’ll give you some choices:
1) Every person in the country is going to get vaccinated.
2) Three-quarters of the population will get vaccinated.
3) One-half of the U.S. population will get vaccinated
4) One-quarter of the U.S. population will get vaccinated
Now take your answer (no looking please), and answer the following “when” question, about when all of those people in your answer get vaccinated:
1) Everyone vaccinated in one month
2) Everyone vaccinated in three months
3) Everyone vaccinated in six months
4) Everyone vaccinated in nine months
5) Everyone vaccinated in one year
So what are your answers? If I show you my answer, you show me yours.
My answer: half the U.S. population gets vaccinated, and it takes 9 months to do that. My reasoning? Do you really think that the half of the U.S. that is protesting masks is going to rush out and get vaccinated? And what happens to mask wearing when a vaccine is approved? Do you think mask wearing will increase, stay the same, or decrease? (My answer is decrease).
Why am I asking these questions? Well let’s suppose a vaccine is approved today, November 19, 2020. When will it start being available? Let’s say January 1, 2021. Now let’s say that half the U.S. population gets vaccinated (half of 330 million is 165 million people). Let’s say it takes 9 months to vaccinate 165 million people. That means that about 18 million people a month would get vaccinated.
What do our COVID-19 case counts look like in March or April, if only 50-60 million people have been vaccinated, and most of the rest of us have given up on masks? Here is a hint:
We are about to hit the 13 million case count line (we are over 12 million cases, and adding more than 150,000 cases a day, so in a week or 10 days we will hit that). We are over 250,000 deaths. What will it look like in the U.S. if a vaccine is approved, and we let our guard down even more than we already have?

I had a periodontist appointment the other day, and we were talking about COVID-19. As I was leaving her office, she said “we have failed the Stanford Marshmallow Test”.
Yes indeed.