New neuroimaging research published in Brain Structure and Function provides insight into why faces with threatening emotional expressions tend to be easier to remember than non-threatening faces. The findings indicate that neural systems involving the prefrontal regions of the brain play a key role.
“We were interested in whether the emotional face expression has an impact on long term memory,” said study author Benjamin Becker (@bn_becker), a professor and head of the neuSCAN Lab at the University of Electronic Science and Technology of China.
“Imagine you are in a subway and incidentally encounter a number of people – will you remember those that look angry at you better? Would you remember them better even after a very long time such as meeting them again after 1.5 years? Such a mechanism would also be advantageous from an evolutionary perspective. Angry or fearful face expressions often signal the presence of danger and thus their long-term recognition is vital to avoid potential threats in the future.”
In the study, 89 healthy, right-handed Chinese students viewed a series of 50 male and female Asian faces, which had angry, fearful, sad, happy and neutral expressions, as the researchers used functional magnetic resonance imaging to observe their brain activity. The participants were asked to indicate the gender of each face by pressing a button.
The participants then completed a surprise recognition memory test approximately 20 minutes after leaving the scanner. They completed yet another surprise recognition test one and a half years later. In both tests, the students viewed a series of faces that included both the 50 original faces and 50 new faces. They were instructed to indicate whether each face had been shown during the original task or was new.
The researchers found that participants were more likely to recognize faces with threatening (angry, fearful) versus non-threatening (happy, neutral) expressions one and a half years later. In addition, they observed that neural activity in the bilateral inferior occipital gyrus (IOG) and ventromedial prefrontal/orbitofrontal cortex (vmPFC/OFC) was related to differences in the ability to recognize threatening versus non-threatening faces.
“Although face recognition ability varies from person to person, face with threatening expressions i.e. angry or fearful faces can be maintained in our memory over years — even after a single incidental encounter — whereas neutral or also happy faces are forgotten,” Becker told PsyPost. “The initial evaluation of a potential danger and associated activity in prefrontal regions during the first exposure may determine the strengths of the memory advantage for threatening faces.”
Xiqin Liu, the first author of the study, added, “our study used an innovative approach to link between individual memory performance and brain activity. The multivariate method (behavioral pattern similarity analysis) allowed us to capture how individual differences in recognition patterns for five emotional face categories are associated with brain activity. This differentiates our study from most previous ones which only characterize the face memory for each emotion category separately.”
But the study, like all research, includes some caveats.
“Our findings underscore the long-lasting effect of threatening expressions on our face memory,” Becker explained. “Interestingly – and against our expectations – we didn’t find better recognition for threatening faces immediately after we presented the faces but only after 1.5 years. This suggests that the memory formation for threatening faces is enhanced during the consolidation stage that follows the exposure. Future studies are necessary to determine the onset of the memory advantage of the threatening faces and which brain regions underlie the differences during consolidation.”
The study, “Medial prefrontal and occipito-temporal activity at encoding determines enhanced recognition of threatening faces after 1.5 years“, was authored by Xiqin Liu, Xinqi Zhou, Yixu Zeng, Jialin Li, Weihua Zhao, Lei Xu, Xiaoxiao Zheng, Meina Fu, Shuxia Yao, Carlo V. Cannistraci, Keith M. Kendrick, and Benjamin Becker.
