04.03.2019 change 04.03.2019

The brain recognizes faces without the participation of consciousness

Even objects as complex as your own face can be recognized by the brain without the participation of consciousness, showed the scientists from the Nencki Institute. Photo based on Dr. Michał Bola's materials Even objects as complex as your own face can be recognized by the brain without the participation of consciousness, showed the scientists from the Nencki Institute. Photo based on Dr. Michał Bola's materials

Even objects as complex as your own face can be recognized by the brain without the participation of consciousness, showed the scientists from the Nencki Institute. The capabilities of our "unconscious mind" are bigger than we thought, they comment.

At any moment, our senses receive a vast number of various stimuli: sounds, sensations, objects in the field of view. Because the capacity of our attention is limited, we consciously process only a small part of them. What happens to the stimuli that reach our senses but do not gain access to consciousness? Can they affect our behaviour without our knowledge and control?

Research currently carried out at the Nencki Institute of Experimental Biology is aimed at exploring the capabilities of our "unconscious minds". The latest results concerning subconscious recognition of one`s own face appeared in the journal Psychological Science. One of the authors of the article, Dr. Michał Bola presented the results in a release sent to PAP.

"The processes we study are often referred to as +subliminal+, because they take place before the threshold of consciousness. We have known for a long time that our brain is able to subliminally process and analyse various types of simple stimuli. In our research, we try to answer the question whether more complex objects can also be effectively processed and influence our behaviour beyond consciousness" - explains the first author of the publication, Michał Wójcik, currently a PhD student at Oxford.

A face can be an example of such a complex object. Although all faces are quite similar, through the simultaneous analysis of many elements - eyes, lips, nose - our brain is usually able to accurately recognize the faces of people we know. Fast and reliable face recognition is important from the point of view of survival, so it was promoted in the course of evolution. Because of this, there are special areas in the brain that are responsible solely for face recognition. Are brain facial recognition mechanisms so effective that they can work even without the participation of consciousness? The scientists decided to find out.

"Both intuition and previous research dictate that our own face is a very strong and important stimulus for everyone, it evokes various types of feelings or associations, and therefore it effectively attracts our attention. That is why in our study we decided to use pictures of the subjects` our own faces (...). We made a hypothesis that the brain would recognize and react to own face, even if the subjects were not aware that they had seen it" - explains Prof. Anna Nowicka, specializing in the study of mechanisms responsible for processing information about ourselves.

During the experiment, subjects looked at a cross displayed in the centre of the screen. At the same time, pairs of face images were displayed - the subject`s own face appeared on one side of the screen, a stranger`s face on the other side. The subjects were asked to ignore the faces that appeared and not focus on them. The most important part of the whole study was that in half of the presentations the faces were clearly visible and easy to recognize, but in the second half the faces were invisible to the subjects.

How can you display a face photo but at the same time make it invisible? Researchers used the well-known "masking" procedure. The faces were displayed for only 32 ms (one frame of a 30 fps video), and immediately after them, "masks" appeared on the screen- meaningless patterns whose only purpose was to disrupt facial recognition. Additional tests confirmed the effectiveness of this procedure - even with such short presentations, the respondents recognized faces without any problems, but after adding the "mask" they were no longer able to tell if the given picture showed their own face. "This technique allows us to do laboratory studies of the influence of stimuli that reach our senses, but are not strong enough to get into the consciousness" - says Dr. Michał Bola, specializing in the study of unconscious processes.

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Diagram of the face recognition experiment; source: Michał Bola and team

To test whether the brain subconsciously recognized the face, the brain activity of the subjects was recorded with EEG. "It has been known for years that directing attention to one side causes asymmetry of brain activity between the hemispheres. By analysing this asymmetry, we were able to say whether at the given moment the subject`s attention was directed to the face presented on the left or the right side" - explains Maria Nowicka from the Nencki Institute and co-author of the study.

In the published study, the researchers showed that when we see our own face, we direct attention to it without thinking, even if we are instructed not to. "This confirms earlier results of our and other teams` research. Once again we have shown that stimuli referring to +self+, for example your own name or face, are processed preferentially" - Prof. Anna Nowicka comments.

The most important result is proving that the brain automatically directs attention to the face, even when the subjects are not aware that they have seen it. "Even though the subjects did not know that a picture of their own face was being displayed, their brain focused on that side of the field of vision. That means that the brain must have recognized both faces without the participation of consciousness and reacted to the familiar face. It appears that consciousness is not necessary for face recognition" - adds Michał Wójcik.

"We have known for a long time that certain types of simple and expressive visual stimuli attract our attention automatically, without will or conscious decision. One red object among many green objects is an example of such a stimulus. In our study, we show that much more complex objects - such as the face, which consists of many elements and requires a more detailed analysis - may unconsciously attract attention. Our experiment is part of the research trend showing that the capabilities of our +unconscious mind+ are much larger than we thought "- concludes Dr. Bola.

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Authors of the study: Michał Wójcik, Maria Nowicka, Dr. Michał Bola, Prof. Anna Nowicka.

In further studies, scientists want to answer the question why own face attracts attention so effectively and whether the same applies to the faces of relatives. Researchers also want to find out if other complex objects can be effectively processed by our brain without the involvement of consciousness.

The project was financed with the National Science Centre grants.

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