How your brain recognizes faces
Have you ever wondered how the brain can single out a recognizable face in a crowd full of so many other faces and extraneous visual stimuli? Well, now, neuroscientists from the Massachusetts Institute of Technology (MIT) have found some answers.
In a new study, the team discovered two types of attention that explain how the brain is able to focus on someone’s face or other objects when so much other visual stimuli is competing for the brain’s attention.
This first type is focused attention, also known as "object-based attention". In the past, researchers have not explored object-based attention as much as they've studied the second type of attention called “spatial attention”, which has more to do with focusing on a specific location.
However, the MIT neuroscientists found that these two types of attention are actually intertwined, using similar mechanisms and related brain regions, whether the focus of attention is on a recognizable face or on a particular location.
Senior author Robert Desimone, a Professor of Neuroscience and director of MIT's McGovern Institute for Brain Research, said that the interactions “are surprising similar to those seen in spatial attention,” adding that it appears similar to "a parallel process involving different areas."
The prefrontal cortex controls both spatial and object-based attention, as well as many other regions of the brain involving cognitive functions, including which portions of the visual cortex receive sensory input.
Professor Desimone and his colleagues report on their findings in the journal Science, revealing that when it comes to object-based attention, such as when the brain focuses on a face in a crowd, a part of the prefrontal cortex (the inferior frontal junction or IFJ) adjusts the visual processing areas of the brain to recognize certain types of objects.
For the study, participants took part in an experiment where they were shown a series of overlapping images of faces and houses, with the researchers instructing them to look only for faces or only for houses.
The experiment was created to measure object-based attention, instead of spatial attention. This was accomplished because the faces and houses were in the same position; thus, the brains of the participants were unable to use spatial information to distinguish the difference between them.
The MIT neuroscientists are now looking into how the brain is able to shift focus from one type of sensory input to another. For example, how does the brain distinguish between sound and vision, two different types of sensory input?
The goal of this investigation is to find out if people can be trained to control brain interactions in a manner that would help them better focus their attention.
SOURCE: Neural Mechanisms of Object-Based Attention, DOI: 10.1126/science.1247003, Robert Desimone et al., published in Science, 10 April 2014.