Ruhr-Universitaet-Bochum
The world around is complex and changing constantly. To put it
in order, we devise categories into which we sort new concepts. To do this we
apply different strategies.
A team of researchers at the Ruhr University Bochum (RUB) led by
Prof. Dr. Boris Suchan, department of neuropsychology, and Prof. Dr. Onur
Güntürkün, department of biopsychology, wanted to find our which areas of the
brain regulate these strategies.
The
results of their study using magnetic resonance imaging (MRI) show that there
are indeed particular brain areas, which become active when a certain strategy
of categorisation is applied.
When
we categorise objects by comparing it to a prototype, the left fusiform gyrus
is activated. This is an area, which is responsible for recognising abstract
images.
On the other hand, when we compare things to particular examples
of a category, there is an activation of the left hippocampus. This field plays
an important role for the storage or retrieval of memories.
Categories
reduce information load
Thinking
in categories or pigeonholing helps our brain in bringing order into a
constantly changing world and it reduces the information load. Cognitive
scientists differentiate between two main strategies which achieve this: the
exemplar strategy and the prototype strategy.
When
we want to find out, whether a certain animal fits into the category
"bird" we would at first apply the prototype strategy and compare it
to an abstract general "bird."
This prototype has the defining features of the class, like a
beak, feathers or the ability to fly.
But when we encounter outliers or exceptions like an emu or a
penguin, this strategy may be of no use. Then we apply the exemplar strategy
and compare the animal to many different known examples of the category. This
helps us find the right category, even for "distant relations."
Complex
interaction
To
find out where our brain is activated, when it is ordering the world, the
neuroscientists in Bochum performed an MRI scan, while volunteers were
completing a categorisation task. The functional imaging data showed that both
strategies are triggered by different areas of the brain.
The
scientists believe that there is a complex interaction between both learning
patterns.
"The results implicate that both strategies originate from
distinct brain areas. We also observed that, during the learning process, the
rhythm of activation in the two areas synchronised. This shows that both
cognitive processes cannot be neatly separated," explains Boris Suchan.
Further modelling and research must now clarify this
interaction.