The study’s lead author, Christoph Dahl, from the Max Planck Institute for Biological Cybernetics (Germany), explained that humans get used to other people’s faces from the earliest childhood. “We learn to recognize the small facial differences that help distinguish individuals”, for example a large nose or bushy eyebrows. Monkeys are also capable of distinguishing each member of their group in a similar way to humans thanks to the processing of information that they receive directly from each individual’s face. But thisability common to humans and monkeys only serves to recognize individuals of the own species.
This recognition of members of the same species is achievedin a holistic way, that is, processing the face as a perceptual whole and not as a series of independent characteristics. However, facial features such as the mouth, nose and eyes as well as the proportion of the face are still important. “Despitefirst we look at the eyes, our neural functions assimilate the entire face, “explains Dahl.
In the referred study, the scientists used the so-calledthatcher effectto study the mechanisms of facial recognition in macaques and humans. The Thatcher effect consists of inverting the eyes and mouth in a portrait. The alteration of the faces is obvious if the image on the right is observed, but it is barely distinguishable if the face is inverted.
In the experiment, 22 humans and 3 rhesus macaques were shown 40 digital color photos of neutral faces of humans and rhesus macaques. These faces were cut out and placed on a gray background. The stimuli had undergone two manipulations: a photo with eyes and mouth turned and turned upright and another simply turned upright. Both images were then rotated 180 degrees.
Humans and primates coulddetect even the slightest changes in facial features when faces were presented from the right. However, thisabilityit looked considerablydepletedWhen the faces were turned upside downThe scientists also found that the mechanisms are not completely effective when dealing with the faces of other species, as neither the humans nor the macaques participating in the study paid much attention to the extremely grotesque faces of the other species. “It must have been aevolutionary advantageIt is very great both for us and for our fellow monkeys to be able to specifically recognize the faces of our species “, the researchers conclude.
