When Your Brain is Dumbest

Go to Bed

Researchers at the University of Michigan have discovered a new kind of discrimination: alphabetical discrimination. It turns out that teachers give lower grades to students whose last names are later in the alphabet.

“What’s more,” U-M’s report described the research, “those alphabetically disadvantaged students get comments that are more negative and less polite, and show lower grading quality measured by complaints from students.” The data covered 30 million grades from U-M’s Canvas course management system.

What’s going on here? Why would teachers give lower grades and less tactful comments to students whose names trend toward Z?

It’s because grading is tiring, and tired people are mentally clumsy. If teachers are grading alphabetically, the later students are getting an exhausted grader. Having personally graded what feels like 30 million papers in my 20-year education career, I can attest to this. When you’re tired, you’re more irritable. Your willpower is weaker. You don’t have as much of a filter.

We see that tiredness can also affect the quality of student work in the first place. One recent study found that homework is helpful for student learning, but only in small doses. The study reports, “Daily homework benefitted mathematics achievement the most, while three to four days per week was most effective for science. Short-duration assignments proved equally as effective as longer ones in both subjects. Notably, students from advantaged socioeconomic backgrounds did not gain more from homework.” Students get the point of the work with practice, but they lose steam if the assignments are too long.

Some of the best marriage advice I’ve heard is “don’t talk about important things after 10pm.” We call this the Gallagher Principle, after our friends that taught it to us. This advice has saved Sarah and me a lot of grief. (The second best marriage advice I’ve heard is “remove the words ‘always’ and ‘never’ from your vocabulary.”) If teachers give lower grades and more, ahem, candid feedback when they’re sleepy, think about how the love of your life hears what’s been bugging you all day by the time it makes its way through your enervated brain at 10:15.

The point is: don’t make important choices when you’re tired. 

You can be physically clumsy, too. I see this in my children. The other night we let our kids stay up too late. When I finally sent them upstairs to get ready for bed, two out of the four children somehow injured themselves in between downstairs, the bathroom, and their beds. That's a 50% casualty rate. One of them whacked his foot against the bedframe while launching himself into bed, and another simply walked into a doorframe. By the time she climbed into bed she had a bump on her poor little head. Both were crying and whimpering as we tried to get them settled in. 

Stress and hunger have a similar effect. One study looked at the connection between test scores and the amount of calories in school lunches. They found that on days in which the school lunch had more calories, students got better test scores. Kids who come to school hungry are a step behind.

In still another study, people were asked to choose between fruit salad (healthy) or cake (less healthy). An unlucky subset was given a math quiz before they were allowed to choose their snack, and these people were more likely to choose cake. In my view they deserved cake, since they had to take a math quiz even though they weren’t even in school.

Of course, that’s just the problem. We feel we deserve to unleash our emotions when we’re tired, hungry, angry, or stressed. Your dumb brain runs rampant while your smart brain is left in the dust, muttering “maybe don’t do that.”

Here are some takeaways:

• Enforce your children's bedtimes. They need it.

• Invoke the Gallagher Principle. No important conversations after 10:00 p.m.¹

• Give yourself and your kids snacks before grocery shopping, as I discuss in How to Stop Your Kids From Bugging You to Buy Stuff.

• Randomize the papers you are grading 

• Cramming for a test late into the night won’t work

It can be difficult to avoid making decisions when you're tired. You may even feel like you’re always tired, especially if you’re the parent of a preschooler. But it's wise to make some rules for yourself about when you make important choices. Sort of like the cerebral version of “don't drink and drive.” When you know you’re not at your best, confiscate your mental keys and get to sleep.

“You need to have an end in sight. Set limits,” Sarah just now told me.

“Stop typing.”

1. There is an exception to the Gallagher Principle in the case of late-night theorizing on the front porch with friends. Somehow these ideas are all brilliant and we should make a podcast, bro.