A new study has revealed yet another dimension of "face recognition". They say that the emotions a person's face displays are key to recognizing the same face at a later date.
Researchers in the Netherlands and at Massachusetts General Hospital, led by Beatrice de Gelder, say their study suggests that using naturalistic emotional faces and bodies in studies- aimed at determining why some people find it difficult to recognize those whom they have met before- may be very helpful in understanding face blindness.
They have come to this conclusion after finding that the presence of emotional information in the face increases neural activity in the fusiform face area (FFA) of the brain that is associated with face recognition, something that can be used to design novel assessment and training programs.
During the study, the researchers used functional magnetic resonance imaging to compare the ability to process faces in a group of individuals reporting life-long problems in recognizing people and with particular difficulties when meeting familiar people unexpectedly-developmental prosopagnosics-with a control group matched for age, sex and education level.
Their aim was to determine how the neural underpinnings of face and body processing in prosopagnosia are influenced by emotional information in the face and the body.
For that purpose, they ran a series of tests on the participants, assessing abilities such as object and face recognition and perception, face matching and face memory.
The researchers found that compared to the control group, the developmental prosopagnosia group displayed a similar activation level in FFA for the emotional faces, but a lower activation in the area for neutral faces.
They say that their findings are consistent with the view that there is a higher threshold for the recognition of neutral faces in prosopagnosics.
According to them, the relative difficulty with neutral faces is based on the idea that faces are more difficult stimuli than many of the other categories with which they are routinely compared.
The researchers also observed during the study a higher activity level of activity in the amygdala-the brain region associated with emotional reactions-for emotional faces compared to neutral ones.
The results of this study demonstrate the importance of emotional information in face processing and the researchers urge future imaging studies to take into account the modulatory effect of emotion, in order to further untangle the complex nature of developmental prosopagnosia.
A research article describing the study has been published in the open-access journal PLoS ONE.