> So what they did was they had these listeners, while they were listening to songs were a wearable device, sort of like an Apple Watch, or a Fitbit, something

> So what they did was they had these listeners, while they were listening to songs were a wearable device, sort of like an Apple Watch, or a Fitbit, something that can track your cardiac activity. So your your heart rate, for instance. And they collected this cardiac data, and use it as a proxy for brain activity by putting it through this commercial platform immersion neuroscience, which claims to be able to measure emotional resonance and attention by using cardiac data.