Brain detects happiness more quickly than sadness
Wednesday, June 17, 2009
People make value judgements about
others based on their facial expressions. A new study, carried out be Spanish
and Brazilian researchers, shows that – after looking at a face for only 100
milliseconds – we can detect expressions of happiness and surprise faster than
those of sadness or fear.
Our brains get a first impression of people's
overriding social signals after seeing their faces for only 100 milliseconds
(0.1 seconds). Whether this impression is correct, however, is another question.
Now an international group of experts has carried out an in-depth study into how
we process emotional expressions, looking at the pattern of cerebral asymmetry
in the perception of positive and negative facial signals.
The
researchers worked with 80 psychology students (65 women and 15 men) to analyze
the differences between their cerebral hemispheres using the "divided visual
field" technique, which is based on the anatomical properties of the visual
system.
"What is new about this study is that working in this way
ensures that the information is focused on one cerebral hemisphere or the
other", J. Antonio Aznar-Casanova, one of the authors of the study and a
researcher at the University of Barcelona (UB), tells SINC.
The results,
published in the latest issue of the journal Laterality, show that the right
hemisphere performs better in processing emotions. "However, this advantage
appears to be more evident when it comes to processing happy and surprised faces
than sad or frightened ones", the researcher points out.
"Positive
expressions, or expressions of approach, are perceived more quickly and more
precisely than negative, or withdrawal, ones. So happiness and surprise are
processed faster than sadness and fear", explains Aznar-Casanova.
The
two faces of the brain
This research study adds to previous ones,
which had revealed asymmetries in the way the brain processes emotions, and
enriches the international debate in cognitive-emotional neuroscience in terms
of how to define the exact way in which human beings process these facial
expressions.
People make deductions from the expressions on people's
faces. "These inferences can strongly influence election results or the
sentences given in trials, and have been studied before in fields such as
criminology and the pseudoscience of physiognomy", the neuroscientist tells
SINC.
Two theories are currently "competing" to explain the pattern of
cerebral asymmetry in processing emotions. The older one postulates the
dominance of the right hemisphere in the processing of emotions, while the
second is based on the approach-withdrawal hypothesis, which holds that the
pattern of cerebral asymmetry depends upon the emotion in question, in other
words that each hemisphere is better at processing particular emotions (the
right, withdrawal, and the left, approach).
"Today there is scientific
evidence in favour of both these theories, but there is a certain consensus in
favour of the lateralisation of emotional processing predicted by the
approach-withdrawal hypothesis", concludes Aznar-Casanova.
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FECYT - Spanish Foundation for Science and Technology