How the brain processes language – Professor Ina Bornkessel-Schlesewsky
October 31, 2019
Imagine a world without language.
Communication in both our personal and professional lives would be profoundly different.
Society as we know it could not exist. Language is an ability that comes so naturally
to us that we mostly – take it for granted. We tend to only consider its impact and its
complexity when something “goes wrong”. For example, when an elderly relative has
a stroke and has difficulty speaking OR when a child struggles to read and is diagnosed
with dyslexia OR when we find it difficult to learn a foreign language.
In our study, we examined whether – in brain terms – natural language processing in context
can be traced back to a very fundamental mechanism of information processing in the brain: prediction.
Cognitive neuroscience research over the past 20 years has revealed that the human brain
is essentially a prediction machine. This is important as it allows us to interact
with the world around us. For example, think about action-planning and
motor control. If I want to carry out a very simple movement,
such as reaching out and picking up a bottle of water, my brain does two things in parallel
One, it sets up the required motor program for the action and two, it computes what the
world would be like if the action were carried out successfully. If there is a mismatch, for example if the
bottle is slipping away and I don’t get the expected tactile feedback, my brain can
use this to correct the motor program in an instant.
There is a brain signature of this “predictive coding”: brain activity to the same sensory
input differs depending on whether it is predicted or not
There is essentially a deactivation of relevant brain areas when the stimulus is predicted
as opposed to when it is not. Our study showed that this aspect of information
processing in the brain is also operative when we understand complex linguistic input.
In our research, we had 20 young, healthy adults listen to short stories while they
were lying in an MRI scanner – a machine which allows us to measure activity changes
in the brain during a certain task. Within each story, we introduced certain characters,
for example an engineer, and then mentioned this character again, later in the story.
We then compared changes in brain activity when the characters were mentioned again,
depending on how predictable their re-mention was.
When we did this, we saw a deactivation of a range of regions in the brain for more predicted
versus less predicted re-mentions of a story character.
One of the main regions showing this pattern was the inferior parietal lobe, a part of
the brain which is known to be important in integrating information from a wide range
of sources –such as processing of a language in context.
This study is the first to show that prediction – as a fundamental mechanism of information
processing in the brain – is also in operation when we process language
We hope that this research will also eventually allow us to address real-world challenges
such as language rehabilitation after brain injury or how to optimise foreign language