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Why Brain Activity Doesn’t Reveal Our Minds

There is poor correlation between different scans of even the same person’s brain, experienced researchers say

At one time, we were told that, one day, machines will read our minds. But, now researchers say, the more we know about the brain (set aside the mind for a moment), the more reasons we have for doubt:

But a new analysis by some of the researchers who have done the most work in this area finds that those measurements are highly suspect when it comes to drawing conclusions about any individual person’s brain.

Karl Leif Bates, “Studies of brain activity aren’t as useful as scientists thought” at Duke Today

Brain scanning—functional MRI (fMRI)—tells us about general brain structures, says Duke University neuroscientist Ahmad Hariri, who led a team that reanalyzed the data. It doesn’t say much about the details of what is happening:

“Scanning 50 people is going to accurately reveal what parts of the brain, on average, are more active during a mental task, like counting or remembering names,” Hariri said

Functional MRI measures blood flow as a proxy for brain activity. It shows where blood is being sent in the brain, presumably because neurons in that area are more active during a mental task.

The problem is that the level of activity for any given person probably won’t be the same twice, and a measure that changes every time it is collected cannot be applied to predict anyone’s future mental health or behavior.

Karl Leif Bates, “Studies of brain activity aren’t as useful as scientists thought” at Duke Today

When Hariri’s team reexamined 56 published papers based on fMRI data, they found that “the correlation between one scan and a second is not even fair, it’s poor.” Here’s the paper.

Maybe we have got it backwards. Our minds read things but it doesn’t follow that we can read our minds. We can’t even read brains. Which is not even the same thing.

Neuroscientist Matthew Cobb has written a book that addresses the basic problem, The Idea of the Brain (April 21, 2020). In an extract published at The Guardian, he confesses,

Every day, we hear about new discoveries that shed light on how brains work, along with the promise – or threat – of new technology that will enable us to do such far-fetched things as read minds, or detect criminals, or even be uploaded into a computer. Books are repeatedly produced that each claim to explain the brain in different ways.

And yet there is a growing conviction among some neuroscientists that our future path is not clear. It is hard to see where we should be going, apart from simply collecting more data or counting on the latest exciting experimental approach. As the German neuroscientist Olaf Sporns has put it: “Neuroscience still largely lacks organising principles or a theoretical framework for converting brain data into fundamental knowledge and understanding.” Despite the vast number of facts being accumulated, our understanding of the brain appears to be approaching an impasse.

Matthew Cobb, “Why your brain is not a computer” at The Guardian (February 27, 2020)

Cobb points out that the brain has been compared to a telegraph, a telephone exchange, or hydraulic system, according to whatever technology was changing people’s lives. But images are imagination, not information. Our brains, like our lives, are unique, and are always reinventing themselves (neuroplasticity). Our goals for research must take these facts into account.

Further reading:

We will never “solve” the brain. A science historian offers a look at some of the difficulties we face in understanding the brain

How far has AI mindreading come? Further than we may think. And some trends are troubling


Elon Musk’s myths about the mind. According to Musk, everything in the brain is an electrical signal. That’s pretty naive

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Why Brain Activity Doesn’t Reveal Our Minds