Role of ordinal contrast relationships in face encoding
Name
Gilad-2009-Role of ordinal cont.pdf
Size
1.29 MB
Format
Adobe PDF
Checksum (MD5)
5883e3324f8abf335f9581923e3fccaa
Author(s)
Gilad, Sharon
Meng, Ming
Sinha, Pawan
Date Issued
March 2009
Journal
Proceedings of the National Academy of Sciences of the United States of America
Publisher
National Academy of Sciences
Citation
Gilad, Sharon, Ming Meng, and Pawan Sinha. “Role of ordinal contrast relationships in face encoding.” Proceedings of the National Academy of Sciences 106.13 (2009): 5353-5358.
Version
Final published version
Abstract
What aspects of facial information do we use to recognize individuals? One way to address this fundamental question is to study image transformations that compromise facial recognizability. The goal would be to identify factors that underlie the recognition decrement and, by extension, are likely constituents of facial encoding. To this end, we focus here on the contrast negation transformation. Contrast negated faces are remarkably difficult to recognize for reasons that are currently unclear. The dominant proposals so far are based either on negative faces' seemingly unusual pigmentation, or incorrectly computed 3D shape. Both of these explanations have been challenged by recent results. Here, we propose an alternative account based on 2D ordinal relationships, which encode local contrast polarity between a few regions of the face. Using a novel set of facial stimuli that incorporate both positive and negative contrast, we demonstrate that ordinal relationships around the eyes are major determinants of facial recognizability. Our behavioral studies suggest that destruction of these relationships in negatives likely underlies the observed recognition impairments, and our neuro-imaging data show that these relationships strongly modulate brain responses to facial images. Besides offering a potential explanation for why negative faces are hard to recognize, these results have implications for the representational vocabulary the visual system uses to encode faces.
MIT Department
Massachusetts Institute of Technology. Department of Brain and Cognitive Sciences
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
http://dx.doi.org/10.1073/pnas.0812396106
