If you’ve ever tried to tune into one conversation and tune out others in the din of a crowded room, you know it can be challenging — but definitely doable for most of us. There’s even a name for the phenomenon: the cocktail party effect.
But just how does our brain pull off this trick? It’s not as if we can physically focus our ears the way we can our eyes, points out Israeli cognitive neuroscientist Elana Zion Golumbic. She was part of a team whose study on selective attention was reported in the March 6 issue of the Cell Press journal Neuron.
“We have so much information coming into our senses all the time, and we are challenged to choose what to pay attention to and what to ignore,” Golumbic said. “This is such a relevant and important aspect of our lives.
“All sounds in the environment come into your ears, so selection has to be done internally,” said Golumbic, 34. “Engineers have been trying for decades to amplify important parts and reduce background noise, and it’s quite challenging computationally. Yet human beings apparently do this well. That’s why I find it fascinating.”
The research provides the first clear evidence of brain locations where there is exclusive representation of attended speech, while ignored conversations get filtered out.
Golumbic conducted the “cocktail party effect” study in New York at Columbia University with Dr. Charles Schroeder and colleagues from other universities. They recorded electrical brain activity of patients who were shown simultaneous videos — one with a woman speaking, one with a man speaking and another with both speaking simultaneously. When asked to concentrate on the male speaker, they automatically focused their eyes on him.
The subjects’ brains had registered both attended and ignored speech, but not in the same regions of the brain.
“There was an ‘aha’ moment the first time I saw that switching attention between two speakers causes a dramatic change in the way the brain is responding, despite the fact that the sensory input to the ears was identical,” Golumbic said. “To see it manifested in the brain was what we were looking for, and it was very dramatic.”