Back in the 19th century, a French criminologist named Alphonse Bertillon invented a technique for recognizing repeat offenders by precisely measuring convicts’ facial features. Fingerprinting eventually supplanted his system, but new research done on macaques shows primate brains can naturally keep track of faces thanks to a kind of bertillonage.
The discovery, reported in June in Cell, completely breaks with the standard model of facial recognition, which claims each face you recognize is represented by a single neuron (one cell firing when you see your grandmother, another when you see Jennifer Aniston). Instead, Caltech neuroscientist Doris Tsao showed that individual primate neurons respond to specific facial qualities, such as bone shape and skin color.
Inserting electrodes into the brains of two macaques, Tsao worked out which aspects of a face were mapped onto each neuron. Then she validated her findings by showing the macaques additional faces, and accurately reconstructing what they’d seen using only neural recordings.
Tsao predicts that, with advances in human brain-monitoring technology, “the ability to decode faces by neuronal activity can be used in forensics, such as reading out a criminal’s face from a witness’ mind.” Are you watching, Monsieur Bertillon?
