Making Sense of Nonsense

"I really like wearing this new lipstick!" Coming from your sister, this comment probably wouldn't sound strange, but if your brother said it, you'd likely do a double-take. New research helps explain why.

We all notice when someone says something we don't expect. The surprise arises, linguists believe, because the brain uses information about people to make sense of what they say. Some scientists have assumed that the brain processes the meaning of a sentence first, then worries about who said it. Psychologist Jos van Berkum of the University of Amsterdam in the Netherlands and his colleagues were curious about whether this sequence actually held true.

The research team attached 12 men and 12 women to an electroencephalograph (EEG) that measures brain electrical activity with high temporal resolution. Then the volunteers listened to sentences that were made nonsensical by an out-of-place word. These semantically incorrect sentences, such as "I wash my hands with horse and water" caused a big spike in brain activity 200 to 300 milliseconds after the misplaced word occurred. No spike occurred during the control: "I wash my hands with soap and water."

The same spike in brain activity occurred when the speaker said something unexpected, even if it was grammatically correct. When a male voice said, "I wish I looked like Britney Spears in her latest video", for example, the EEG spiked 200 to 300 milliseconds after the onset of the word that made the sentence unexpected, in this case, "Britney." There was no spike in brain activity when a woman spoke those words. The team also found that the shape of the recorded brain waves in response to semantically and contextually incorrect sentences was the same, implying that the same region of the brain may be involved in recognizing both types of information.

The results show that the brain takes into account the speaker and what that person is saying at the same time, says van Berkum, whose team reported its findings 9 July at the 5th Forum of European Neurosciences in Vienna, Austria.

This work is "interesting and well presented," says cognitive neuroscientist Lorraine Tyler of the University of Cambridge in the United Kingdom. The development of newer techniques, such as magnetoencephalograpy, which measures the magnetic fields produced by electrical activity in the brain, will help localize the source of the brain signals, she says. Researchers might then be able to pin down exactly which parts of our brains send us into shock when dad says he wants to be Britney Spears.

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Posted in Brain & Behavior