Studying Face Blindness Requires Naturalistic Emotional Stimuli

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Main Category: Eye Health / Blindness
Also Included In: Neurology / Neuroscience
Article Date: 19 Sep 2008 - 0:00 PDT

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Face blindness is a condition that affects about 2% of the population's ability to do what many consider an effortless task - to recognize faces of family, friends, and other acquaintances. A small number of people find it difficult to identify the person with whom they are meting or remembering people that they have previously met. Some, in fact, cannot recognize the faces of spouses, children, or even their own faces. To better understand developmental face disorders, recent research on face blindness stresses the importance of using naturalistic emotional faces and bodies.

A study published in the open-access journal PLoS ONE and written by researchers from the Netherlands and Massachusetts General Hospital discusses an interesting finding about how the brain interprets face information. Beatrice de Gelder (Tilburg University, Tilburg, The Netherlands) and colleagues demonstrate that increased neural activity in the fusiform face area (FFA, the area of the brain associated with face recognition) is associated with the presence of emotional information in the face. The researchers believe that this finding can assist the design of new assessment and training programs. In addition, the study reveals that people with face blindness do not have body and face sensitive processes are that are as categorically segregated, which suggests cortical specialization as a potential cause of the disorder.

Faces offer information on a person's gender, age, emotion, familiarity, and attractiveness. Depending on the context, these details can be called upon and used either quite rapidly or after full recognition of facial attributes, including a name. In order to evaluate face recognition problems and to understand it neuro-functional basis and potential deficits, the contextual requirements and the task settings are very important.

De Gelder and colleagues used functional magnetic resonance imaging (fMRI) to assess how well a group of individuals could process faces. The participants all suffered developmental prosopagnosics; that is, they reported life-long problems in recognizing people and particular difficulties when meeting familiar people unexpectedly. These people were compared with a control group that was matched for age, sex and education level. The aim of the research was to find out how the neural underpinnings of face and body processing in prosopagnosia are changed by emotional information in the face and the body. The participants received a series of tests that assessed their ability to recognize objects and faces, their perception, and their ability to match and memorize faces.

The analysis by De Gelder and colleagues revealed that the developmental prosopagnosia group displayed a similar activation level as the control group in FFA for the emotional faces, but the developmental prosopagnosia also displayed a lower activation in this area for neutral faces. Therefore, there is a higher threshold for the recognition of neutral faces in these prosopagnosics. Neutral faces are believed to be more difficult because these faces are more difficult stimuli than the other categories with which they are usually compared.

Faces that are showing emotion contain an additional feature that provides important communicative information and thus the emotional stimuli trigger a higher level of arousal. The researchers also observed that when prosopagnosics looked at emotional faces, there were high activity levels in the amygdala - the region of the brain that deals with emotional reactions - than when looking at neutral ones.

The authors conclude that: "The results from the present study clearly demonstrate the importance of emotional information in face processing and urge (future imaging) studies to take the modulatory effect of emotion into account, in order to further untangle the complex nature of DP [developmental prosopagnosia]."

Neural Correlates of Perceiving Emotional Faces and Bodies in Developmental Prosopagnosia: An Event-Related fMRI-Study
Van den Stock J, van de Riet WAC, Righart R, de Gelder B
PLoS ONE (2008). 3(9):e3195.
doi:10.1371/journal.pone.0003195
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About PLoS ONE

PLoS ONE is the first journal of primary research from all areas of science to employ both pre- and post-publication peer review to maximize the impact of every report it publishes. PLoS ONE is published by the Public Library of Science (PLoS), the open-access publisher whose goal is to make the world's scientific and medical literature a public resource.

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Written by: Peter M Crosta
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