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STOP THE PRESSES: New Evidence Against Adult Neurogenesis
Andrew Watson
Andrew Watson

For many decades, neuroscientists believed that adult brains don’t generate new neurons. Once childhood is over, the neurons you have are all the neurons you’ll get.

Theadult neurogenesisn, in the 1960s, we started seeing evidence that adult brains DO INDEED create more neurons.That evidence got even stronger in the 1980s — believe it or not by studying songbirds.

When you go to Learning and the Brain conferences, you doubtless hear about adult neurogenesis. It is, we thought until this morning, one of the reasons you can learn new things.

Today’s Headline: No Adult Neurogenesis?

This article has been cropping up all over my newsfeed. It’s headline: “Birth of New Neurons in the Human Hippocampus Ends in Childhood.”

The article is easy to read, and I encourage you to give it a look. It offers a helpful historical context, and digs into the implications of these findings.

The findings are so new that I haven’t yet seen much response to them. I’ll post updates as scholars start to grapple with this research.

In the meanwhile, you can take confidence from this research that skepticism never flags. Even so “well-established” a finding as adult neurogenesis can be overturned when we get better data.

As Arturo Alvarez-Buylla, one of the researchers, say:

“I always try to work against my assumptions in lab,” he said. “We’ve been working on adult neurogenesis so long, it is hard to see that it may not happen in humans, but we follow where the data leads us.”

Omega 3 Fish Oil Doesn’t Help, but Research Does
Andrew Watson
Andrew Watson

In 2012, researchers in Britain found that Omega 3 fish oil benefited students who struggled in schools. In fact, it helped students both concentrate better and learn more.

omega 3 fatty oilThat was exciting news, because we can provide those dietary supplements relatively easily. It sounded like an easy way to fix to a real problem.

However, other studies didn’t confirm this result. For that reason, the original lab decided to try a replication study. In other words: they repeated what they had originally done to see if they got the same results.

Omega 3 Fish Oil: The Bad News

Nope, they didn’t help.

You can review the study here. Most impressive — and most discouraging: chart after chart and graph after graph showing no meaningful difference between the students who got Omega 3 supplements and those who didn’t.

(By the way: nobody knew who got the supplements until after the study. It was, as they say, “blind.”)

In the muted language of research, the authors conclude:

In summary, this study did not replicate the original findings of significant, positive effects of omega-3 DHA on either learning or behavior. No systematic adverse effects from the supplementation were observed. As such the study does not provide supporting evidence for the benefits of this safe nutritional intervention.

Alas, this easy solution simply doesn’t pan out.

The Good News

The system worked.

When researchers come across a positive finding, they should both spread the news and double check their work.

That is, they should let us know that omega 3 fish oil might be beneficial, and run the study again to be sure.

Of course, replicating a study is expensive and time consuming; it’s easy to decide that other research priorities are more important.

In this case, however, the researchers did what they ought to have done. As a result, we know more than we did before. And, we’re not wasting time and money stuffing our children with needless dietary supplements.

We should all tip our hats to this research team for doing the right thing. I don’t doubt they’re disappointed, but they’ve shown themselves to be a real model for research probity.

(For another example of researchers sharing conflicting results, see this story from last October.)

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PS: After I finished writing this post, I came across another article about fish. It might not help with working memory, but it just might help prevent MS.

Despite the Skeptics, a Champion of Direct Instruction
Andrew Watson
Andrew Watson

In the debates between “progressive” and “traditional” educational theories, few arguments rage hotter than the battle between project based learning and direct instruction.

PBL’s proponents take a constructivist perspective. They argue that people learn by building their own meaning from discrete units of information.benefits of direct instruction

In this view, teachers can’t simply download conclusions into students’ brains. We can’t, that is, just tell students the right answer.

Instead, we should let them wrestle with complexities and come to their own enduring understanding of the material they’re learning.

An Alternative Perspective: The Benefits of Direct Instruction

In a recent meta-analysis, Jean Stockard’s team argues that direct instruction clearly works.

Looking at 300+ studies from over 50 years, they conclude that DI benefits students in every grade, in a variety of racial and ethnic groups, with a variety of learning differences, from every socio-economic background.

Of course, this research conclusion challenges some often-repeated assurances that direct instruction simply can’t help students learn.

(The recent meta-analysis is, unfortunately, behind a paywall. You can, however, see some impressive graphs in an earlier white paper by Stockard.)

Another Alternative Perspective: Reinterpreting “Constructivism”

Interestingly, Stockard doesn’t disagree with a constructivist understanding of learning. Instead, she sees direct instruction as a kind of constructivism.

“DI shares with constuctivism the important basic understanding that students interpret and make sense of information with which they are presented. The difference lies in the nature of the information given to students, with DI theorists stressing the importance of very carefully choosing and structuring examples so they are as clear and unambiguous as possible.”

(This quotation comes from a brief pre-publication excerpt of the meta-analysis, which you can find here.)

In other words: in Stockard’s view, the difference between PBL and DI isn’t that one is constructivist and the other isn’t.

Instead, these theories disagree about the kind of information that allows students to learn most effectively.

Simply put: PBL theorists think that relatively more, relatively unstructured information helps students in their mental building projects. DI theorists think that relatively less, relatively tightly structured information benefits students.

Stockard makes her own views quite plain:

“It is clear that students make sense of and interpret the information that they are given–but that their learning is enhanced only when the information presented is explicit, logically organized, and clearly sequenced. To do anything less shirks the responsibility of effective instruction.”

You might mentally add a “mic drop” at the end of that passage.

Other Sources

Of course, lots of people write on this topic.

John Hattie’s meta-meta-analyses have shown DI to be quite effective. This Hattie website, for example, shows an effect size of 0.60. (For Problem based learning, it’s 0.12; for Inquiry based teaching, it’s 0.35.)

If you like a feisty blogger on this topic, Greg Ashman consistently champions direct instruction.

And, I’ve written about the difficulties of measuring PBL’s success here.