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Why do we sometimes not see what is directly in front of us? Researchers at the Georgia Institute of Technology and University of California Berkeley studied the role of the frontal cortex in perceptual decision-making by utilizing transcranial magnetic stimulation. The study was published in the peer-reviewed journal Proceedings of the National Academy of the Sciences of the United States and later discussed in a recent article in Medical Xpress:  

A sportscaster lunges forward. "Interception! Drew Brees threw the ball right into the opposing linebacker's hands! Like he didn't even see him!"

The quarterback likely actually did not see the defender standing right in front of him, said Dobromir Rahnev, a psychologist at the Georgia Institute of Technology. Rahnev leads a research team making new discoveries about how the brain organizes visual perception, including how it leaves things out even when they're plainly in sight.

 

Rahnev and researchers from the University of California, Berkeley have come up with a rough map of the frontal cortex's role in controlling vision. They published their findings on Monday, May 9, 2016 in the journal of theProceedings of the National Academy of Sciences.

 

Thinking cap

 

The frontal cortex is often seen as our "thinking cap," the part of the brain scientists associate with thinking and making decisions. But it's not commonly connected with vision. "Some people believe that the frontal cortex is not involved," said Rahnev, an assistant professor at the School of Psychology. The new research adds to previous evidence that it is, he said.

 

The lack of association with that part of the brain may have to do with the fact it's other parts that transform information coming from the eyes into sight and others still that make sense of it by doing things like identifying objects in it.

 

But the thinking cap of the brain controls and oversees this whole process, making it as essential to how we see as those other areas, Rahnev said. How that works also accounts for why we sometimes miss things right in front of us.

 

A camera it's not

 

"We feel that our vision is like a camera, but that is utterly wrong," Rahnev said. "Our brains aren't just seeing, they're actively constructing the visual scene and making decisions about it." Sometimes the frontal cortex isn't expecting to see something, so although it's in plain sight, it blots it out of consciousness.

 

To test out the fontal cortex's involvement in vision, the researchers ran a two-part experiment.

 

First, they observed which regions of the brain—in particular the frontal cortex—lit up with activity while healthy volunteers completed visual tasks corresponding to three basic stages of conscious visual perception.

 

Second, they inhibited those same regions using magnetic stimulation to confirm their involvement in each visual stage.

 

Believing is part of seeing

 

The first stage of the visual perception the researchers tested for was selection, Rahnev said. That's when the brain picks out part of the vast array of available visual stimuli to actually pay attention to.

 

In the case of the football quarterback, this might mean focusing on the route the receiver takes.

 

The second stage is combination, he said. The brain merges the visual information it processed with other material. "The quarterback's brain is putting what he actually sees together with expectations based on the play he called," Rahnev said.

 

Then comes evaluation. The quarterback needs to decide whether to release the ball given everything he has processed.

 

Expecting a blocker to stop the defending player (which didn't happen), he may have blotted him out of perception and thrown the ball right at him. Interception.

 

"The frontal cortex sends a signal to move your attention onto the object you select," Rahnev said. "It does some of the combining with other information, and then it's probably the primary evaluator of what you think you saw."

 

Simple vision brain map

 

In experiments, during a functional MRI scan, different parts of the frontal cortex of the participants lit up, corresponding to each vision function.

 

The back of the frontal cortex activated during selection; its midsection lit up during combination, and the front, or anterior, part cranked up during evaluation.

 

That's how the researchers arrived at a kind of vision map of the frontal cortex. "It's a rudimentary map," Rahnev said. "A very simple one that just says, 'This is the back. This in the middle. This is the front.'"

 

The critical evidence

 

The critical evidence for this map came from the use of magnetic stimulation. When the researchers used it to inhibit the back and middle of the frontal cortex separately, subjects became less able to complete the corresponding functions of selection and combination.

 

When they stimulated the front, the opposite happened. Subjects were slightly but significantly better able to evaluate the accuracy of what they think they saw.

 

"This is a really clear demonstration of the role that the frontal cortex, which is usually seen as the seat of thought, plays in controlling vision."

 

Sorry officer!

 

And there is a practical takeaway for health and safety. Instead of the quarterback telling the coach, "I swear I didn't see that coming," often it's motorists telling police officers the same thing after a car accident.

 

Distraction is often the culprit, because it overtaxes the organization of perception, Rahnev said. These three functions are going on all the time in multiple scenarios in our brains while it processes the world around us.

 

But add too much to the pile, like texting behind the wheel, Rahnev said, and "you can run right into a parked car without ever seeing it."

Read the original Here

Mirror neurons are thought to be the switching point between visual and motor centers in the brain. Mirror neurons help our brain to interpret the actions of others. When someone raises a fist toward us do they mean to give us a friendly greeting (fist bump) or do they mean to attack us? Researchers at the Max Plank Institute studied the role of mirror neurons in action recognition. The study was discussed in a recent article in Medical Xpress: 

It is suspected that mirror neurons enable us to empathize and put ourselves 'in other people's shoes'. When we see that someone has been injured, we also experience internal suffering: these special neurons cause what we see to be simulated in our brain in a way that makes us feel as though we are experiencing it in our own bodies.

 

In perception research, it is assumed that mirror neurons enable people go through a movement they have seen in their own motor system. This internal recreation of what we have seen probably enables us to infer the meaning of the observed action. The mirror neurons act as the switching point between the motor and visual areas of the brain. Conversely, when the motor system is supposed to be the determining factor in the classification of an action, it means that the perception can also be manipulated by our own implementation of an action.

 

Attack or greeting?

 

In their study, the researchers analyzed the mechanism by which the brain recognizes an action. To do this, they showed the test subjects two different movements: a punch and a greeting gesture known as the 'fist bump', practised by young men in particular. The researchers arranged the scenario as realistically as possible. A life-sized avatar was shown on a screen facing the test subjects. Using 3D glasses, the subjects were able to see their virtual partners in three dimensions – the avatar's movements appeared as though they were unfolding within the test subjects' reach.

 

All the test subjects were required to do was to decide whether they were being presented with an aggressive punch or well-intentioned greeting. However, the scientists made the conditions more difficult by combining the two gestures in a single movement. The avatar's intentions were thus a matter of interpretation.

 

The question behind the experiment then was whether people allow themselves to be influenced by their own motor system when interpreting the actions of others. The test subjects were manipulated in different ways in the experiment: they could observe a clearly identifiable action played in a continuous loop on a screen. They became active at the same time themselves by carrying out air punches, for example. They were then asked to assess how the indefinable movement of the avatar should be interpreted.

 

I only believe what I also see

 

When the two sensory stimuli were played out against each other – that is the test subjects saw a fist bump in front of them while carrying out a punch movement themselves – the visual impression was the clear winner. The subject's own movement did not have any influence on the perception. Contrary to what was previously assumed, the motor system had little or no influence on the participants' assessment of the movement. To the astonishment of the scientists, the mirror neurons associated with the motor system clearly did not have any major role to play in the action recognition process.

 

With their experiment set up, the team was able to study the contribution of the motor system to action recognition during social interaction for the first time and, thereby also the existing theory on the interaction between mirror neurons and stimulus processing. "Contrary to what was previously assumed, the mirror neurons do not have a particularly significant influence on the interpretation of an action. Visual perception is namely far more important for our brain – in social situations, we rely almost exclusively on what we see," says the head of the study, Stephan de la Rosa, summarizing the study findings.

Read the original article Here