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Of two minds: Listener brain patterns mirror those of the speaker

The views expressed are those of the author and are not necessarily those of Scientific American.


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two women talkingA new study from Princeton University reports that a female student of lead investigator, Uri Hasson, can project her own brain activity onto another person, forcing the person’s neural activity to closely mirror that in her own brain. The process is otherwise known as speech.

There have been many functional brain-imaging studies involving language, but never before have researchers examined both the speaker’s and the listener’s brains while they communicate to see what is happening inside each brain. The researchers found that when the two people communicate, neural activity over wide regions of their brains becomes almost synchronous, with the listener’s brain activity patterns mirroring those sweeping through the speaker’s brain, albeit with a short lag of about one second. If the listener, however, fails to comprehend what the speaker is trying to communicate, their brain patterns decouple.

Previously, most brain-imaging studies of language used repetition of simple sounds to stimulate a listener’s brain to locate regions mediating listening or they involved a speaker repeating simple words to examine cerebral areas involved in speech production. This disjointed approach was necessary because analyzing fMRI (functional magnetic resonance imaging) data requires repeating a stimulus many times during successive brain scans to average the responses and find regions exhibiting heightened or depressed activity. Also, the imaging machines are noisy, which makes it difficult to have a normal conversation. These past approaches, however, are not adequate studies of communication, which requires that the recipient is attentive and comprehends what the speaker is saying. If, for example, a teacher is lecturing and a student who is listening intently has become lost, there is a failure of communication.

In order to find out what happens in the brain when the speaker and listener communicate or fail to connect, Hasson, an assistant professor in Princeton’s Department of Psychology, and his team had to first overcome both technical problems using new analytical methods as well as special nonmagnetic noise-canceling microphones. He asked his student to tell an unrehearsed simple story while imaging her brain. Then they played back that story to several listeners and found that the listener’s brain patterns closely matched what was happening inside the speaker’s head as she told the story.

   

The better matched the listener’s brain patterns were with the speaker’s, the better the listener’s comprehension, as shown by a test given afterward. There was no mirroring of the speaker’s brain activity patterns if the listeners instead heard a different story recorded previously by the same speaker and played to them as a control experiment. English speakers listening to a story told in Russian did not show higher-level brain coupling. In other words, there is no mirroring of brain activity between two people’s brains when there is no effective communication (except for some regions where elementary aspects of sound are detected.  When there is communication, large areas of brain activity become coupled between speaker and listener, including cortical areas involved in understanding the meaning and social aspects of the story.).

Interestingly, in part of the prefrontal cortex in the listener’s brain, the researchers found that neural activity preceded the activity that was about to occur in the speaker’s brain. This only happened when the speaker was fully comprehending the story and anticipating what the speaker would say next.

"Communication is a joint action, by which two brains become coupled," Hasson explained in an e-mail. "It tells us that such coupling is extensive, [a property of the network seen across many brain areas]."

The team is interested in determining if nonverbal communication similarly causes mirrored brain activity in the recipient’s brain, and whether communication in the animal world may have similar properties. "We are thinking about fly courtship song and bird songs. In a fly courtship song, only the male can sing. It was discovered however, that females have the capacity to sing, but it is inhibited," Hasson says. This fits with the new findings, because if the female’s brain could not mirror activity in the male fly’s brain they would not be able to communicate. Language binds brains together and in this melding of minds forms societies.

The results are detailed in the July 26 issue of Proceedings of the National Academy of Sciences.

 

ABOUT THE AUTHOR 

R. Douglas Fields, Ph. D. is the Chief of the Nervous System Development and Plasticity Section at the National Institute of Child Health and Human Development and Adjunct Professor at the University of Maryland, College Park. Fields, who conducted postdoctoral research at Stanford University, Yale University, and the NIH, is Editor-in-Chief of the journal Neuron Glia Biology and member of the editorial board of several other journals in the field of neuroscience. He is the author of the new book The Other Brain (Simon and Schuster), about cells in the brain (glia) that do not communicate using electricity.   His hobbies include building guitars, mountain climbing, and scuba diving.  He lives in Silver Spring, Md.

The views expressed are those of the author and are not necessarily those of Scientific American.

Top image: iStockphoto

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Comments 29 Comments

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  1. 1. Flynow32 3:24 pm 07/27/2010

    What about reading? Does the readers brain activity couple with the writers while they were writing?

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  2. 2. Flynow32 3:34 pm 07/27/2010

    Or music?

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  3. 3. dougfields 4:23 pm 07/27/2010

    I wondered about music and reading as well. The analytical approaches used in this study should permit studies of these and other kinds of communication.

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  4. 4. dstallma 4:53 pm 07/27/2010

    Would an autistic brain react the same way?

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  5. 5. egghead1619 5:05 pm 07/27/2010

    I wonder if the same would be true for cases where separate species have developed a rudimentary language understood by both. It would explain why I feel like my dog and I know what each other are thinking. Sometimes it even seems like she’s screaming at me (with only non-verbal cues) to let her out, get some food, or play with her. The same type of study could even be done in regards to sign-language and other forms of communication.

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  6. 6. jtdwyer 6:08 pm 07/27/2010

    The article states:
    "When there is communication, large areas of brain activity become coupled between speaker and listener, including cortical areas involved in understanding the meaning and social aspects of the story."

    Intended or not, stating that ‘brain activity become coupled between speaker and listener’ can imply to many readers that there is some unknown, perhaps even mystical or supernatural form of nonverbal communications in effect, producing synchronous electrical activity in the brain.

    I think obviously, the similar electrical activity is produced by the elementary verbal communications: envisioning someone ‘walking down the street’ produces similar brain activity in both the speaker and listener.

    Does the author really intend that the reader envision that some mystical process has been discovered here? I think further testing would be necessary to establish such a extraordinary claim.

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  7. 7. dougfields 9:23 pm 07/27/2010

    Thank you for your question. No, Im sure the author of the study did not intend to imply a mystical process couples two brains when they communicate. Rather that it is a necessary to control the recipients cognitive and perceptive brain function to have effective communication. It goes to the essence of language, which is quite amazing when you consider it. Information, personal feelings, and intentions get transformed into thoughts, and we then execute precise and very complex motor functions to generate utterances; the listener must analyze these sounds and decode them into words, sentences, paragraphs, and extract meaning. To convey thoughts, information, and emotions by sound (and I would imagine by the pattern of ink on a page) requires that the sender can control appropriate parts of the listeners brain to make them match the patterns of activity in his own brain. This enables perception to occur so that the intended meaning is evoked inside the recipients brain. Not mysticism, but other issues of perception are raised. Considering the recent popularity of movies like Avatar and Inception, fictions that involve getting inside another persons brain and controlling it, I thought this study was interesting in revealing that humans have already achieved this in the form of language and the evolution of brain circuitry that makes it all possible.

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  8. 8. jtdwyer 10:01 pm 07/27/2010

    dougfields – Thanks very much for explaining. However, IMO any listener that engages in perceiving thoughts, information and emotions communicated by a speaker is doing so voluntarily and cooperatively, in the interest of their own needs. Otherwise, one could control an uncooperative listener by speaking to them. If you’ve ever tried to communicate with an unruly child, and ex-spouse or traffic cop to convince them of something against their will, you must agree that cooperation is necessary to achieve control through communication.

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  9. 9. Johnay 10:13 pm 07/27/2010

    I wonder if in the far future students and teachers might wear brain imaging caps connected to a system that would identify which students didn’t quite get it (and what parts) and which were totally not "there". Could make for more efficient use of tutors and study time.

    @jtdwyer: Some might read that into it, if they were to ignore the fact that the listeners were hearing not live but recorded speech, and that a difference in language was sufficient to spoil the effect. (Some will, of course, ignore those facts, as they do others that would otherwise falsify what they want to believe.)

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  10. 10. jtdwyer 10:57 pm 07/27/2010

    IMO, there is no actual ‘remote control’: this may be evidenced in any case in which the listener can successfully anticipate the speaker’s story. If the speaker was controlling the listener’s brain, the ‘matching’ or similar brain patterns could only occur after receiving the speaker’s ‘commands’.

    In the case of animals that have less sophisticated brain functions, there may be less conscious choice involved, but the listener is still most likely actively cooperating in the faithful reproduction of the message sent.

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  11. 11. dougfields 12:30 pm 07/28/2010

    You raise an interesting point. I suppose there would be a divergence in brain patterns in this situation where there is a failure to communicate, just as in the other situations where communication breaks down. However, the divergences would probably be in somewhat different areas of the brain.
    What I could not describe in my brief article were the interesting results of phase shifting the correlations in time between the brain patterns in the speaker and listener brain from 6 second delays to 6 second advances. Brain processing takes time. Different parts of the brain coupled at different times relative to the moment of vocalization. That is how the researchers discovered that activity in part of the listener’s brain actually preceded activity in the speaker’s brain. These anticipatory responses take time to process and they show that some higher-order brain areas (the parietal lobe for example) have the capacity to accumulate information over many seconds. What this means, though, is that our perceptions will be affected by what we expect to hear.

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  12. 12. jtdwyer 1:47 pm 07/28/2010

    dougfields – Yes, I hadn’t really considered the uncooperative or non-participating listener’s brain activity, but it must be expected to diverge.

    This is very interesting. As I understand, the reproduction of brain activity patterns occurred even when listing to a recording. This indicates to me that all the ‘control’ information is contained withing the sounds patterns and its language encoded information.

    It also occurs to me that the cooperative process could perhaps be best described as empathy – the process of reproducing the speaker’s brain patterns is successful to the extent that the listener actively empathizes with the speaker. I’m considering empathy here to mean imaginatively envisioning the story events being described.

    If you’ve indicating that the sequence of brain area activation varied between speaker and listener, I’d guess that the process of producing an imaginary story environment may vary somewhat between individuals, as opposed to the simpler serial decoding of verbal messages. This asynchronous processing may be considered as evidence that the more complex process of empathetic listening is occurring.

    The anticipatory process is interesting. Computer architectures implement similar capabilities called ‘instruction pre-fetch’, which may involve guessing which instruction path will be followed, to reduce processing time. The variability of brain pattern reproduction delay may be a measure of the processing complexity required for the message. That may vary, along with the success rate of brain pattern reproduction for more complex less agreeable stories.

    I think that the brain pattern reproduction is a voluntary action of the listener to invoke high level empathetic and imaginative processes to more faithfully receive the message content, rather than a manifestation of speaker control over the listener, Adolph Hitler notwithstanding.

    Hopefully my language has been close enough to the specialized terminology of your scientific discipline to effectively communicate. I think that’s very important to establish ‘street cred’ and compatible communication protocols and message encoding. But then, I’m just guessing.

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  13. 13. Dr.d 7:20 pm 07/28/2010

    This finding is part & parcel of our BPS Model of consciousness where we have analyzed how, as mediated by premotor ‘mirror neurons’, an observer focusing on a person about to execute an adaptive response can anticipate the probable behavior of the subject being observed. See http://pulse.yahoo.com/_VHN6HSYWK3LTKWCTZZFCKR2C3U/blog/articles/186981?listPage=index Dr.d

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  14. 14. Razausman 2:26 am 07/29/2010

    That should be obvious. The thought is a pattern which is ‘decoded’ as the same pattern on the receiver.
    In essence specific thoughts have particular patterns in the human brain

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  15. 15. e-llas 2:32 am 07/29/2010

    In the WEB 2.0 world it will be interesting to know if it works for online conversations, where the sound and mimics are absent.

    Is that the difference between a good writer and a bad one?

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  16. 16. bill benzon 9:30 am 07/29/2010

    These results are both exciting and not surprising. Back in the late 60s and early 1970s William Condon did high-speed video taping of people interacting with one another. He found, for example, that the listener’s head and body movements tracked the intonation patters of the speaker’s language. Interestingly enough, this was true even for neonates, their body motions tracked speech patterns of nearby speakers.

    I made such interactional synchrony the conceptual centerpiece of my 2001 book on music, Beethoven’s Anvil. I also reprise and extend some of those ideas in my essay-review of Steven Mithen’s The Singing Neanderthals:

    http://www.human-nature.com/nibbs/05/wlbenzon.html

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  17. 17. Manos 1:06 pm 07/29/2010

    I have two remarks, and would be grateful if you could comment on them.
    1. "Prefrontal cortex activation precedes the speaker’s brain activations". Does that mean that the listener was able to predict (by activating its own symbolic representations) the future of the story? Were aspects of the story anticipated by the listener?

    2. Are your findings related to other studies on mirror activations (e.g. the mirror neurons in the Ventral Premotor of the Macaque) and possibly the Theory of Mind? Or they describe how speaking and listening can transform thought in similar ways?

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  18. 18. jtdwyer 3:33 pm 07/29/2010

    As a lay reader, IMO, it has been established that ‘mirror neurons’ fire both when an individual physically takes action and the individual observers the same action taken by other individuals. It seems to be mostly involved in physical mimicry, imitation and repetition. While this mirror processing may be involved in language acquisition, it does not appear to be involved with language comprehension.

    As I understand, mirror processing has been detected by MRI studies in humans to occur specifically in the inferior frontal cortex, thought to be involved in language processing.

    In this experiment, it seems that the speaker must imagine a simple story to tell. It seems that both imagining a story as it is being told and, and imagining the story upon hearing it, similar disperse areas of the brain are activated. I suggest that these areas being activated are primarily related to the act of imagining the story.

    That similar areas are activated upon voluntary, cooperative imagination of a simple story as its imagination and telling should not infer that the speaker exerts any kind of control over the listener, especially since the listener is contacted only through an audio recording, with ‘no strings attached’.

    Often the simplest explanation is all that’s necessary – any more is embellishment…

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  19. 19. Trelligan 10:51 am 07/30/2010

    This opens up a fascinating possibility for education. First, record the neural output of a lecturer, along with the lecture itself.
    Next, monitor the neural activity of a listener, comparing it on-the-fly with the lecturer’s.
    Significant decoupling would indicate lack of understanding. This could open the way to a measure of lecture effectiveness, and even perhaps interactive lectures, switching to an amplified explanation of areas not properly understood.

    Naturally, this would require significant improvement in the technology. This might be realized (at least partly) by learning which are the best indicators, and creating monitors optimized for those particular indicators.

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  20. 20. jtdwyer 11:50 am 07/30/2010

    Trelligan – Yeah, monitoring employees’ comprehension of management communications in the workplace would be great fun, too…

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  21. 21. dougfields 5:50 pm 07/30/2010

    jtdyler–The authors do discuss mirror neurons in their article. "The production/comprehension coupling observed here resemble the action/perception coupling observed within mirror neurons. Mirror neurons discharge both when a monkey performs a specific action and when it observes the same action performed by another. Similarly, during the course of communication the production-based and comprehension-based processses seem to be tightly coupled to each other. " Have a look at the Discussion section of their paper.

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  22. 22. jtdwyer 7:04 pm 07/30/2010

    dougfields – I’d be happy to take a look at the paper, but I can’t find it. A link would have been nice, but the only hint I found was the mention of Uri Hasson and the statement:
    "The results are detailed in the July 26 issue of Proceedings of the National Academy of Sciences." I didn’t even find a title…

    I don’t find anything in the PNAS July 27, 2010 archives by
    Uri Hasson. Did I miss something?

    Wikipedia’s Mirror Neuron entry states:
    "A mirror neuron is a neuron that fires both when an animal acts and when the animal observes the same action performed by another.[1] Thus, the neuron "mirrors" the behavior of the other, as though the observer were itself acting. Such neurons have been directly observed in primates, and are believed to occur in humans and other species including birds. In humans, brain activity consistent with that of mirror neurons has been found in the premotor cortex and the inferior parietal cortex."

    I’m not sure why we’d be discussing mirror neurons in monkeys in relation to this study, but I’ll be happy to review the paper, if I can only find it.

    If the brain patterns reproduced involve regions outside of the premotor cortex either non-mirror neurons are involved or Wiki (certainly less than a definitive, authoritive source of information) is in conflict regarding potential human mirror neurons.

    Thanks in advance.

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  23. 23. jtdwyer 4:15 pm 07/31/2010

    By the way, does the listener’s brain activity patterns mirror those of the speaker if the speaker is given a story to simply read? I predict not, as the brain pattern being produced in the original experiment primarily reflects the process of imagining the story.

    I predict that a story reader who is instructed to not imagine the story being read will not produce all of the brain activities as a speaker contemporaneously making up an original story.

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  24. 24. cgraves 9:29 am 08/3/2010

    Is there any evidence or reason to believe the actual narrative structure affects the mirroring? In other words, while it was clearly stated something incomprehensible did not create neural coupling, are there degrees of effectiveness caused by more highly-descriptive narrative versus sparse plot summary? This would indicate the need not just to tell a story but to tell a good one in order to be effective. I am not a scientist, but assume the areas of the brain would indicate whether the listener is recreating movies or pictures in their own brain while the speaker is narrating.

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  25. 25. hfpsycho 1:15 pm 08/11/2010

    Further comments on the Mirror Neuron Commentary…Mirror Neuron Systems in Humans are also posited (see http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0030079 work by Marco Iacoboni on emotions and mirror neurons). In a related discipline called embodied psychology, the perceptual coupling between perceiver and world would and could exist between two percievers and each other as each perciever would be an aspect of the given context of the situation.

    Also addressing the question of whether we could predict the future of a persons story based on all of the aforementioned factors in this discussion, it is also my opinion that this is likely possible due to mirror neurons, pattern recognition and anticipatory neural response. If the person is empathizing with the other via the use of mirror neurons and recognizing the patterns (physical and psychological) in their language and body movements, and the person has had a similar experience to which is being described by the other then yes, it then becomes conceivable that people could predict what happened next in the story (Unless it was a really crazy story, like the flight attendant out of control).

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  26. 26. Notlostintranslation 10:18 pm 08/30/2010

    "In other words, there is no mirroring of brain activity between two people’s brains when there is no effective communication (except for some regions where elementary aspects of sound are detected." That explains why when language interpreters are tested they score low or fail. There are three testing components: sight translation, consecutive and simultaneous interpretation. Almost everyone aces sight translation. In consecutive translation, a script is read making pauses for the translation. There’s also a script for simultaneous interpretation. This is much harder, the interpreter is decoding and encoding with a lag of approximately four seconds. This is a must read for those who specialize in interpreter’s testing. I bet the scores will be different should the testing be done in a real communication setting.

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  27. 27. verdai 6:33 pm 09/12/2010

    I could only wish and pray that this were always true.
    there are just Too many times and places when the listener is already outside the circle of the speaker before any communication can be even attempted, and it is something like mindset.

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  28. 28. eflood91 8:47 am 09/23/2010

    The author of this study by no means believes that the matching brain patterns of speaker and listener are of a magical nature. This is a scientific experiment, and therefore has the pursuit of explaining all things through research and rational explanations. Being a student, I find the idea of my brain activity matching and following that of my professor (when I am listening, that is) fascinating. Communication is such a vital link between humans in our world, and it seems this study is just the tip of the iceberg in a whole new realm of how we process what others are saying. In our bustling world, slowing down and studying how and what someone is saying and how it affects their and the listeners brains is such a different idea, and the results of matching patterns is astounding. I for one can’t wait to read what this scientist comes up with next. And I am positive it will have nothing to do with mystics and magic.

    Link to this
  29. 29. mchllsmth15 9:04 am 10/27/2010

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