📷 McMaster University
Journalist: Emily O’Halloran
Interviewer: So, we're joined today with doctor Laurel Trainor the director of the McMaster University's live lab welcome.
Dr. Laurel: Thank you.
Interviewer: So, as director of live lab what are some of the most ground-breaking studies that you have encountered?
Dr. Laurel: Well we have done a lot of things in the life lab it's a very flexible space, we have active acoustics in there so we can change in an instant the reverberation and how where sounds are coming from in someone we can also measure EG and multiple musicians as I play together or in audience members we can do detailed analysis of their movements measured heart braid other physiology so it's an incredibly flexible space and so there's quite a few projects that are are pretty interesting that we've done in there. Some of the ones that are most interesting to me have to do with music and nonverbal communication, yeah so we all know that music affects us emotionally it can make us feel better when we're sad but it also can have more therapeutic effects so in development music actually can help the brain get wired up for language and for perception in general but we really don't understand a lot of the social aspects of music. So we have music at parties we have music at weddings, funerals, at sporting events, so we basically have music anytime we want people to come together and feel a common bond. So we've been sort of investigating things around this this topic and so one of the sort of the big puzzles is how do people even play music together so when you when you play music if you're playing an instrument you have to you know play your own notes and be anticipating what's coming up so you're fingers and someone in the right place at the right time but when you play with other people you also have to anticipate what they're going to do and if sort of wait to hear what they do it's too late you're not going to be with them and so the tempo can change, the dynamics can change, the phrasing all that stuff and people feed off each other so we've been investigating just how these these nonverbal cues ex get executed in behavior and in the brain and so one of the things we've done is looked at motion capture of body sway. So when musicians play they have to move their fingers or whatever to play their instrument but they also move their bodies and they really don't have to move their bodies to play their instrument but if they don't move their bodies it's actually hard for them to play and largely they're not even conscious that they're doing these movements it's a little bit like gesturing with your hands when you talk if you prevent someone from gesturing it actually makes it harder for them to talk. So there's something about that motor connection with perception and action that helps us organize our perception and our motor plans about how we're going to execute things. So we measure body sway in musicians as they played together and we found that we could predict from the way one person swayed their body at one moment in time how another musician was going to sway their body next so that means that there's communication and so one musician is affecting the other musician and the second position is also affecting the first musician and so then we've done a series of experiments where we've sort of manipulated this in various ways so we've manipulated in a string quartet who is the leader so normally the first violin but said okay on one trial maybe the viola is now the leader and then we measure how much communication is there for more musician to another and we can actually change the communication patterns among the string quartet by who they think is leading and who they think is following. We've also looked used it to look at emotional expression, so when musicians play emotionally there's a lot more communication that goes on between them and when they just play dead brand.
Interviewer: Yeah yeah.
Dr. Laurel: So it's also reflecting their communication as one of the most interesting things to me is that even when we set up a situation where the musicians can’t see each other the way one is moving is still affecting how another one moves. So we think that this movement is not just the body's way is not just movement but it's actually reflecting their brain processes it's reflecting how they're thinking and how they're planning and phrasing and what they're going to do, so it's sort of a proxy for what's going on in their brain.
Interviewer: So how like how do you think they are picking up on each other’s body language or body movement without actually seeing them?
Dr. Laurel: Yeah so I don't believe in mental telepathy so it’s got to be through the sound. Interviewer: Right.
Dr. Laurel: So the way the sound that a musician produces is actually telling how they gonna play next so there might be some subtle thing they might be slowing down a little bit and that telling you oh you know maybe were coming to the end of the phrase in their mind here so the sound itself is communicated and they can pick up on those cues in the sound And predict how each other going to play over the next bit and that enables them to play together.
Interviewer: So would you say that like in professional musicians that's probably a lot more prevalent than in like people who haven't been playing as long, or do you think that anyone no matter their musical level like could pick up on those cues like you think that's just inherent to people?
Dr. Laurel: Yeah that's a great question and it's probably homed in professional musicians but I think we all have it and one of the things about music that's really interesting is its timing structure so it's rhythm right and if you think about it rhythms are so powerful because they are they enable prediction. So if you have a steady beat you know so you have you know exactly when the next beat right is going to be expected right so we know that the brains and other studies that we've done we know that the brain is constantly predicting what is gonna happen next and when it's gonna happen next and so this timing rhythmic timing structure music really enables that and you don't have to be a musician to feel that right. So if you think about it you couldn't really dance to music at all if you weren't able to predict when the next beat was going to occur 'cause if you wait to hear oh there's a beat and now I'm now I should move my foot or whatever it's it's too late so your brain has to predict ahead of time when you should do those movements so we all have these these very strong predictive capacities.
Interviewer: But probably musicians have honed them actually in the situation of playing music and other experts in different fields probably have honed them to different.
Dr. Laurel: For sure you know people who are you know say soccer players or hockey players the best players are the ones you know not only that can kick the ball the best or whatever but are also the ones that are best at predicting where the other players are going to go because in those specially those teams forced you know basketball, soccer, hockey, you have to predict where in the next few seconds other people are going to be on the field so that if you're going to pass the ball or whatever you know your teammate is going to be there and you know you try to predict another someone from the other team is not going to be there so these predictive processes are found everywhere and they're also in our social interaction so another study that we did in the life lab was on actually speed dating an so in just communication with someone you've never met before and you have 3 minutes to have an interaction with them we measured again using this the same idea we measured their body sway and we measured how predict if the bodies wave one person was with their partner and vice versa an we found that we could actually predict who was going to match at the end of the evening from how communicate if they were in terms of their body swing.
Interviewer: Ouu interesting.
Dr. Laurel: So it's not just some esoteric thing that happens in music and we're kind of using music as a model for understanding social interaction in general.
Interviewer: Right right, so have you ever encountered results that you just didn't expect at all like you you know you made your hypothesis and then they just something totally different happened.
Dr. Laurel: Yeah well I guess initially in the study I described earlier where when they couldn't see each other body sway was still predictive
Interviewer: Okay.
Dr. Laurel: We didn't expect that at all we thought okay we'll be able to eliminate body sway because it's a visual cue so if they can't see each other then they they shouldn't show communication by body sway and they did, and so that made us really think again about what is body sway reflecting.
Interviewer: Right.
Dr. Laurel: And so we thought well now we think it's actually reflecting thought processes. Which is which is pretty cool and so we've also now moved to doing EEG studies where we measure brain responses between groups of musicians as they play an also between audience members as they experience a concert.
Interviewer: Right.
Dr. Laurel: So with the brain measures we have a more direct sort of measure what's going on in people's brains and we can show there as well that there's communication between musicians and it's not just that their brains are going to do similar things at similar times so synchrony there is synchrony that that happens but what sort of more interesting to me is that there's also predictive processes going on so you can look at the same brain state that's going on in one person and from that you can predict what another person in the musical group what their brain is going to be doing moments later.
Interviewer: Wow okay.
Dr. Laurel: So so you can actually measure we call that communication or in theoretically is called information flow but it really is communication from one signal to another in this case the brain signal of 1 person to the brain signal of another person.
Interviewer: Wow very cool, so is there any way I guess just body sway I know you said it reflects thought process is is there any way to kind of have almost a quantitative measure based on some sort of body movement or sum like an EEG or something of human emotion or is that more so you have to ask people about it and it's just up to the individual to say what they were feeling at that time?
Dr. Laurel: Yes, you can get you will get certain activation of certain areas in the brain so the limbic system when people are experiencing emotions those measures are more easily gained with techniques like MRI.
Interviewer: Oh.
Dr. Laurel: than with the EEG because the limbic system is quite deep in the brain so we don't get as good a signal from the from those areas of the brain when we do EEG however that said emotional experiences will also show up in other physiology. So for example something that we measure is galvanic skin response and basically it's tiny increases in sweating.
Interviewer: Oh.
Dr. Laurel: So for example we can put a couple of sensors on your finger and we can measure how the conductance basically, so how much sweat there is how much water there which affects the conductance between those two probes and from that we can measure really subtle changes in emotional responses and generally that mostly reflects arousal so if someone becomes more emotional they'll accept these and they can be very small they might not even be aware that they're sweating a little bit more but we can we can pick that up.
Interviewer: Right and so that indicates higher emotion but it probably doesn't indicate you know whether it's more sadness or happiness or excitement or-
Dr. Laurel: That's right and it turns out that it's much easier for us to measure arousal so emotion has two basic dimensions one is valent so is it positive or negative and the other one is arousal so are you just feeling calm or you feeling very excited and a lot of these measures actually it's the arousal that's easier to measure physiologically.
Interviewer: That makes sense, yeah I actually think that's all the time that we have but it was so nice to talk to you thank you so much very very interesting and mind-blowing they are able to measure all these thought processes with music wow.
Dr. Laurel: My pleasure.