[Editors] MIT: Insights into face recognition

[Elizabeth Thomson]

======================================
MIT: Why we have difficulty recognizing faces in photo negatives
--Work could impact computer vision, autism studies
======================================

For Immediate Release
WEDNESDAY, MAR. 18, 2009

Contact: Elizabeth A. Thomson, MIT News Office
E: thomson at mit.edu, T: 617-258-5402


NOTE TO REPORTERS: the photos available for this story include  
“contrast chimeras” of famous people

CAMBRIDGE, Mass.--Humans excel at recognizing faces, but how we do  
this has been an abiding mystery in neuroscience and psychology. In an  
effort to explain our success in this area, researchers are taking a  
closer look at how and why we fail.

A new study from MIT looks at a particularly striking instance of  
failure: our impaired ability to recognize faces in photographic  
negatives. The study, which appears in the Proceedings of the National  
Academy of Sciences this week, suggests that a large part of the  
answer might lie in the brain's reliance on a certain kind of image  
feature.

The work could potentially lead to computer vision systems, for  
settings as diverse as industrial quality control or object and face  
detection. On a different front, the results and methodologies could  
help researchers probe face-perception skills in children with autism,  
who are often reported to experience difficulties analyzing facial  
information.

Anyone who remembers the days before digital photography has probably  
noticed that it’s much harder to identify people in photographic  
negatives than in normal photographs. “You have not taken away any  
information, but somehow these faces are much harder to recognize,”  
says Pawan Sinha, an associate professor of brain and cognitive  
sciences and senior author of the PNAS study.

Sinha has previously studied light and dark relationships between  
different parts of the face, and found that in nearly every normal  
lighting condition, a person’s eyes appear darker than the forehead  
and cheeks. He theorized that photo negatives are hard to recognize  
because they disrupt these very strong regularities around the eyes.

To test this idea, Sinha and his colleagues asked subjects to identify  
photographs of famous people in not only positive and negative images,  
but also in a third type of image in which the celebrities’ eyes were  
restored to their original levels of luminance, while the rest of the  
photo remained in negative.

Subjects had a much easier time recognizing these “contrast chimera”  
images. According to Sinha, that’s because the light/dark  
relationships between the eyes and surrounding areas are the same as  
they would be in a normal image.

Similar contrast relationships can be found in other parts of the  
face, primarily the mouth, but those relationships are not as  
consistent. “The relationships around the eyes seem to be particularly  
significant,” says Sinha.

Other studies have shown that people with autism tend to focus on the  
mouths of people they are looking at, rather than the eyes, so the new  
findings could help explain why autistic people have such difficulty  
recognizing faces, says Sinha.

The findings also suggest that neuronal responses in the brain may be  
based on these relationships between different parts of the face. The  
team found that when they scanned the brains of people performing the  
recognition task, regions associated with facial processing (the  
fusiform face areas) were far more active when looking at the contrast  
chimeras than when looking at pure negatives.

Other authors of the paper are Sharon Gilad of the Weizmann Institute  
of Science in Israel and MIT postdoctoral associate Ming Meng, both of  
whom contributed equally to the work..

The research was funded by the Alfred P. Sloan Foundation and the Jim  
and Marilyn Simons Foundation.

--END--

Story available online at: http://web.mit.edu/newsoffice/2009/brain-photo-0313.html

Written by Anne Trafton, MIT News Office
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.mit.edu/pipermail/editors/attachments/20090318/f1e48e2a/attachment.htm