Having
evolved with storytelling as a means to pass information across
generations, our brains are powerfully attuned to narratives, so much so
that we can recall well-told stories better than basic facts.
Stories
play a powerful role in shaping the world we've created for ourselves,
and it turns out they may even be able to dictate the rhythm of our own
heartbeats.
Your heart rate fluctuates, naturally, even when you are just sitting there, doing nothing, maybe listening to a story on the radio.Guess what, you are not alone!Some one else listening to the same story will have the same heart rate fluctuations: https://t.co/A5O55JvLTv
"Why does your heart rate go up and down like that?" asks study co-author and biomedical engineer Lucas Parra on Twitter.
"We
think it is because you need to be ready to act, at a moment's notice.
And for that, you need to know what is going on around you. In other
words, you need to be conscious of what is happening. Even if it is just
a story."
Paris
Brain Institute neuroscientist Pauline Pèrez and colleagues monitored
volunteers' heart rates during a series of experiments, using an
electrocardiogram.
Listening to a 1-minute snippet of 20,000 Leagues Under the Sea in
one experiment, or a few minutes of instructional videos in another,
heart rates were seen to synchronize between study participants,
regardless of where they were.
The instructional video showed this phenomenon was not tied with emotion, which is something previous studies have theorized after observing this synchrony in people watching the same movie.
But
disrupting the volunteers' concentration – by making them count
backwards or subjecting them to distracting sounds – diminished their
heart's synchronicity, and their ability to recall the narrative.
Memory
retention has been shown to align with conscious perception, so this
suggests our hearts play a beat in time with our mind's conscious
processing of the narrative, the researchers explain.
"What's important is that the listener is paying attention to the actions in the story," says Paris
Brain Institute neuroscientist Jacobo Sitt. "It's not about emotions,
but about being engaged and attentive, and thinking about what will
happen next. Your heart responds to those signals from the brain."
In
a final experiment, the researchers even tested this on 19 unconscious
patients along with 24 healthy volunteers. As predicted, most of the
patients failed to synchronize their heart rates, all except for two.
One of these went on to regain full consciousness.
"These
results suggest that the patients' [synchronized heartbeats] might
carry prognostic information with a specific emphasis on conscious
verbal processing," the team writes in their paper.
Aside
from changes from physical activity and other stressors, the rhythms of
our hearts fluctuate naturally all the time. This has been attributed
to autonomic processes – the automatic, unconscious parts of our bodies'
regulation, but this study shows conscious processes play a role too.
"There's
a lot of literature demonstrating that people synchronize their
physiology with each other. But the premise is that somehow you're
interacting and physically present in the same place," says Parra.
"What
we have found is that the phenomenon is much broader, and that simply
following a story and processing stimulus will cause similar
fluctuations in people's heart rates. It's the cognitive function that
drives your heart rate up or down."
Pèrez
and team suspect that individual words (as well as the overall meaning
of the narrative and the emotions they inspire) drive the synchronicity,
and they note a cohesive narrative is crucial to create synchronized
activity seen in brain scans.
But
they caution that this is a very small study, with each of the
experiments consisting of only 20-30 subjects, so the results will need
to be verified with larger groups of people. Comparisons with brain
scans could possibly help determine if narratives are indeed the cause
of the heartbeat synchronicity too.
"Neuroscience is opening up in terms of thinking of the brain as part of an actual anatomical, physical body," says Parra.
"This
research is a step in the direction of looking at the brain-body
connection more broadly, in terms of how the brain affects the body."
"People think they react to the world in their particular way,'' adds biomedical
engineer Jens Madsen from the City College of New York. "[But] even our
hearts react in a very similar way when we listen to short stories.
That makes me smile. We're all human."
This research was published in Cell Reports.