If you were hoping I’d find a neuroscientist who’d say that standardized tests, like the MCAS or PARCC, are a bunch of bunk—I’m sorry to disappoint you.

John Gabrieli, a neuroscientist at the McGovern Institute for Brain Research at MIT, says that, like them or not, standardized tests are pretty good when it comes to measuring a student's abilities.

"We and other researchers have consistently found academic achievement tests of the kind given by states in the United States correlate considerably with other independent measures of cognitive ability," Gabrieli said.

But they can’t do everything.

"These kind of tests test academic knowledge," Gabrieli said.

That’s known as "crystallized intelligence"—the knowledge and skills you learn in the classroom. But measuring “fluid intelligence”—applying reasoning skills in an unfamiliar context—is trickier.

"You can’t use your knowledge of math, history, [you] have to think on the spot with something that’s novel, something you haven’t seen before," he said.

To better understand this, Gabrieli and his colleagues looked at a group of Boston students who went to schools that had significantly improved their MCAS scores. What they found surprised him.

Some schools managed to "boost" test performance considerably— and a lot of the other good things that go along with test performance—without boosting core cognitive skills, such as fluid reasoning or working memory capacity.

"That’s not the sort of thing we’ve asked schools to prepare students for," Gabrieli said.

Now before you get mad at schools for not teaching kids fluid intelligence, consider this:

"There are no known practices that promote those kinds of abilities," Gabrieli said. There’s a lot of research going on, some promising studies here and there, but there is no curriculum or training program that can be offered to schools

That regularly increase these kind of cognitive skills.

But what about how the brain itself reacts to—as critics put it—high-stakes standardized tests?

Po Bronson and Ashley Merryman explored that for their book

“Top Dog: The Science of Winning and Losing.”

"The most innovative and landmark study in this area was done in Taiwan, where children coming out of 9th grade have to test into high schools," Bronson said. "It’s an incredibly hard two-day test, only 40 percent of kids pass the test."

A stressed-out brain is flooded with higher levels of dopamine, which can cloud thinking. The study in Taiwan examined how that played out with the students taking the exam.

The stress and pressure floods the synapses with too much dopamine, and half of kids brains are equipped to clear that, such that they actually perform better under stress," Bronson said.

They found it was almost like the A students trade places with the B students at test time. The kids with the genotype that helps them perform better did eight points better on average.

But that doesn’t have to mean that half of all kids are doomed by their biology to be bad test-takers.

"No one likes to hear, 'I’ve got the bad gene, I suck at this,'" Bronson said. "What you can do is unwind that narrative."

Bronson says reading a simple statement at the beginning of a test, that frames the experience in a less stressful way, has been shown to work wonders.

Back at MIT, Gabrieli says that there are other ways to get the brain in optimum shape for test days.

"Everything from nutrition you’ve had, and the long run the morning of the test, the quality of sleep can have a huge influence on how you express your potential, the orderliness of chaos of home environments or school environments will all contribute," he said. "For all us to express our best ability on a test, we need to be at our strongest, positive mode."

Just don’t get all stressed out trying to stay positive.