A crash in visual processing can occur when the brain is overwhelmed with more information than it can handle and visual stimuli do not make the full journey to and from the front of the brain, according to a study published by Georgetown University neuroscientists Oct. 23.
The study aimed to explain why humans sometimes forget images they just saw, a phenomenon the researchers dubbed a “crash in visual processing.” Georgetown neuroscience professor Maximilian Riesenhuber was the senior investigator who conducted the study along with investigators Patrick Cox (COL ’08, MED ’17), Clara Scholl (MED ’15) and lead author Jacob Martin, a Georgetown postdoctorate fellow.
The human brain can process up to 70 images per second, according to an Oct. 23 Georgetown University Medical Center news release. However, prior studies have shown that people are rather poor at detecting objects that appear close together in time, a contradiction the study sought to reconcile, according to Riesenhuber.
“Our study shows a specific limitation of the visual system and explains why our consciousness cannot keep up,” Riesenhuber said in a GUMC news release. “When someone tells you they didn’t see something that occurred in a chaotic situation, maybe they did, but they didn’t know that they did.”
The researchers displayed a series of 12 images per second and recorded the participants’ memory of the contents of the images using electroencephalography tests, which record electrical activity in the brain.
The study determined that visual crashes ultimately result from an interference of the feedback wave, otherwise known as the process of image recognition and understanding.
When the human eye detects something, the visual signal travels along a pathway that starts at the back of the brain and moves towards the frontal cortex, according to the report. This is known as a feedforward wave.
After reaching the frontal cortex, the signal is sent back to the back of the brain, making the brain conscious of the processed stimulus. This is known as a feedback wave. However, if an individual sees another image before the signal processing is complete, a visual crash occurs.
Besides identifying where cognition can falter, the study’s findings also shed light on methods for improving cognition, according to the news release.
“The researchers say their conclusions not only are relevant to how, when and where capacity limits in the brain’s processing abilities can arise, but also have ramifications that span consciousness to learning and attention,” the news release said.
Understanding how the feedforward and feedback signal loop work could ultimately help facilitate learning and cognitive processing. Changing the manner in which images are presented increases people’s ability to detect successive images by 73%, according to the report.
This finding shows the possibility of improving the brain’s ability to process visual stimuli, according to Martin.
“We were able to improve participants’ detection and categorization performance by presenting the animal images so that the feedback process of one avoided the feedforward process of the other,” Martin wrote in an email to The Hoya. “Taken together, the results paint a picture that describes human visual processing as a dynamic system in which multiple items (e.g. animals) can potentially coexist and intermingle together in different parts of the brain.”
Neurotechnology can be used to highlight the connection between neural processes and human consciousness and awareness, Riesenhuber wrote.
“We want to understand how the three pounds of fat between our ears do these amazing things that allow us to survive in a complex world, and to see how our brain function can be improved,” Riesenhuber wrote. “The study advances our understanding of how the brain relates to the mind.”