A study by the University of Barcelona (UB) has analysed which facial features our brain examines to identify faces. Our brain adapts in order to obtain the maximum amount of information possible from each face and according to the study the key data for identification come from, in the first place, the eyes and then the shape of the mouth and nose.
The objective of this study, undertaken by researcher Matthias S. Keil from the Basic Psychology Department of the UB and published in the prestigious US journal PLoS Computational Biology, was to ascertain which specific features the brain focuses on to identify a face. It has been known for years that the brain primarily uses low spatial frequencies to recognise faces. "Spatial frequencies" are, in a manner of speaking, the elements that make up any given image.
As Keil confirmed to SINC, "low frequencies pertain to low resolution, that is, small changes of intensity in an image. In contrast, high frequencies represent the details in an image. If we move away from an image, we perceive increasingly less details, that is, the high spatial frequency components, while low frequencies remain visible and are the last to disappear."
As a result of the psychophysical research carried out prior to the publication of this study, it was known that the human brain was not interested in very high frequencies when identifying faces, despite such frequencies playing a significant role in, for example, determining a person's age. "In order to identify a face in an image, the brain always processes information with the same low resolution, of about 30 by 30 pixels from ear to ear, ignoring distance and the original resolution of the image," Keil says. "Until now, nobody had been able to explain this peculiar phenomenon and that was my starting point".
What Matthias S. Keil did was to analyse a large number of faces, namely those belonging to 868 women and 868 men. "The idea was to fi
FECYT - Spanish Foundation for Science and Technology