Tuesday, January 31, 2012

Left Brain, Meet the Right Brain!

Our first program of the new year was Dr. Shelia Kennison, "This is Your Brain on Words!"

If you really think about it, it's an amazing thing that we can get lost in a book the way we humans often do. I mean, look at a page and what do you see? Black squiggles on a white background. Somehow we turn those squiggles into words and those words into sentences and those sentences into stories that envelop us like waking dreams. What exactly are our brains doing to make that happen?

I performed a new song called "Left Brain" in which Left Brian thinks he can read on his own but in the end he has to admit that Right Brain helps. 
Lisa and Evalyn joined me on the stage for the ending which involves three overlapping musical parts for the left brain, right brain, and corpus callosum. Thanks to Dr. Kennison for sending this photo!!

If brain scanners were faster, we might be able to just watch a person's brain light up as they read. But we decode words way too quickly for any current brain scanning technology to record the process. Dr. Kennison uses an ingenious method that brings us baby-steps closer to understanding what goes on inside when we read. She peeks into the workings of our brains - with grammar. 

When we see a singular noun that might not make sense in a sentence, this doesn't bother us much because singular nouns are often used as adjectives. 

For example, "Sally married the computer..." might not seem so weird once you read the entire sentence: "Sally married the computer repairman."

However, if we make the noun a plural, that's different!

"Sally married the computers..."

There's really no way to finish that sentence so that it makes good sense. 

Dr. Kennison investigates whether these types of grammar glitches can tell us anything about how the brain is working, and she has uncovered some very intriguing patterns.

Dr. Kennison
To understand what Dr. Kennison discovered we need to know about the corpus callosum. This is the part of the brain that connects the left and right sides together. It's the only pathway by which the left side of the brain can "talk to" the right side, and visa versa. 

Just like an internet connection has a particular data transfer rate (or speed), so does a corpus callosum. We call that speed the interhemispheric transfer time, or IHTT. We can measure a person's IHTT at a given moment by having them respond to flashes on a computer screen.

Here our first volunteer measures the speed of his corpus callosum.
For a long time we've known that various different language functions are handled by the left brain. However over the past ten years or so the role of the right brain in language has become more apparent. Dr. Kennison believes that the two halves of our brains are probably always working together to decode language.

She gave her subjects a whole bunch of sentences to read. Some of them had trick plural nouns in them that didn't make sense. Others had weird singular nouns. Others were just regular sentences. She measured if and when each reader slowed down, and by how much. (We're talking about milliseconds here - very small differences in time!)

Here our second volunteer measures his reading speed. He was a quick - I couldn't keep up!
This is what the reading software looks like (projected on our screen). We only get to see one or two words at a time as we move through a sentence. This way the computer can measure our reading speed at each word, and can tell exactly where we might slow down. The software is less detailed than tracking eye movements, but much easier, and gives essentially the same results for the purpose of this experiment.

Then Dr. Kennison measured each of her subject's interhemispheric transfer time. Remember, that's the speed of their corpus collasum. And guess what she found?

The speed of a person's corpus callosum corresponds to the amount they slowed down when reading weird singular nouns. 

What this might suggest is that when we come to an unexpected singular noun in a sentence, the left brain consults with the right brain (via the corpus callosum) to try to make meaning out of the strange word combination. Maybe the right brain is telling the left brain to go ahead and consider the next word because this unexpected noun might make sense as an adjective.

Of course as with any new study, the results are tentative. Dr. Kennison plans to run many more experiments to see if she will continue to observe this interesting effect! And hopefully many more similar experiments will help us better understand how we make meaning out of all those squiggles on a page!

No comments:

Post a Comment