Art of Conversation

As imaging techniques improve, we are approaching the point where we can peer into human brains as they work. Among the most successful of these techniques is functional magnetic resonance imaging (fMRI) that tracks changes in blood flow in the brain. Using this technique, scientists have now been able to understand what happens in the minds of a speaker and listener while a conversation is going on.

Using fMRI, Uri Hasson and her team at Princeton recorded the brain images of one of their students telling a simple story. They then erased the background sound of the machine (which could lead to difficulties in comprehension) and played a recording of the story to a set of listeners. Before Hasson’s work, our understanding of speaking and listening focused on the areas of the brain used for speech and for hearing, but to understand what is going on in the act of comprehending spoken speech it was necessary to treat the conversation as a dynamic interaction between two people.

What the team found should not come as a surprise: the pattern of brain activity in listeners closely mirrors what was going on in the brain of the speaker. This is not limited to activity just in the speech or hearing centres, but concerns what occurs over the entire span of brain activity.

Through much of the conversation, there is expectedly a one second lag between the pattern in the speaker and listener’s brain as the thoughts conveyed in the communication are registered. But at times, a portion of the listener’s brain actually lights up even before what is said is heard, suggesting that the listener is anticipating what is to follow in the story—a true meshing of minds. The researchers also recorded a student relating a story in Russian and played it to listeners who didn’t understand the language. No such coupling of brain activity was observed, a clear indication that the meshing of minds was about understanding a conversation, not about processing speech.