What is it about?
We showed volunteers pictures of faces that changed from one emotional expression to another. At the same time, we recorded their brains' electrical activity using an EEG cap. We found that changing from neutral to emotional faces gave a much bigger response than changing from emotional to neutral. However, a neutral-happy transition was similar to a neutral-frightened transition in the size and shape of the brain's response. Changing the size of the face (bigger versus smaller) showed no difference. We conclude that an increase in the intensity of an emotional facial expression has the greatest effect on the brain.
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Why is it important?
It is important for everyone to be able to understand each others' emotions and facial expressions are one of the main channels for nonverbal communication. Most previous research on the brain's response to emotional facial expressions was based on showing stationary pictures. However, facial expressions are continuously changing, and all expressions arise from a previous expression, so surely that is what we should study. As a first step, we have shown that increases in intensity of facial expression have more effect on the brain than decreases, and that the emotion present in an increasing picture pair is more recognisable than in a decreasing picture pair.
Perspectives
It is perhaps surprising that the EEG response (an average event-related potential, ERP) we measured did not differentiate strongly between different emotions, although the participants themselves could identify the emotions quite easily. A different EEG method (multivariate pattern analysis) should be able to do the identification. The raw data is there on a link to Figshare when you look up the article in PLOS ONE - if anyone wants to try.
Michael Wright
Brunel University London
Read the Original
This page is a summary of: Event-related potentials to changes in facial expression in two-phase transitions, PLoS ONE, April 2017, PLOS,
DOI: 10.1371/journal.pone.0175631.
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