PITTSBURGH - Recognizing a familiar face accurately and almost instantly — despite the frown or smile, the new wrinkles, or beard, or added hat or glasses — involves a mysterious brain process, especially given the many thousands of highly similar faces in a world of billions.
A Carnegie Mellon University study in the Proceedings of the National Academy of Sciences takes important steps in describing the mystery of face recognition, one of the brain's most impressive accomplishments.
"That we are able to recognize tens of thousands of faces with accuracy and rapidity continues to be a scientific mystery," said study leader Marlene Behrmann, who holds an endowed professorship in cognitive neuroscience at CMU. "The question is how this is done, and this study is an attempt to understand that question.
"If we can answer it and lay bare how the brain achieves this, it also offers the possibility that other visual recognition processes may follow the same pattern, including reading, with different type and handwriting."
Cascading brain signals confirming identity "feels effortless," said Behrmann. "It's not like this is hard work. No one is sweating over it. But the speed and lack of effort belies the complexity of the brain computations taking place."
What seems "almost magical," she said, actually involves two complicated brain processes.
The first is appearance-based or image-based, with the brain making literal observations of the face including the shape of nose, mouth or eyes, size of cheeks or type of eyebrows.
Next the brain uses those image-based details in a more abstract, "identity-based" process with neural signals traveling throughout the brain in a give-and-take, back-and-forth process, to analyze and link those facial characteristics to a particular person in memory.
