Have you ever noticed that there are times when you know your eyes see a lot of things, but you don’t actually ‘see’ them because they didn’t register in your brain? This usually happens when you are in a rather chaotic situation or if you are preoccupied with thinking about other things.
A study conducted by a team of neuroscientists from Georgetown University finally found the reason why this happens.
Published on scientific journal, “Journal of Vision”, the study explains that though the brain can process as many as 70 images per second, there’s also what they call as a “crash in visual processing”. When this happens, there is a bottleneck between the signals being sent to and from the brain, making us not aware of what the brain actually recognized.
Neuroscientist Maximilian Riesenhuber, PhD, a professor of neuroscience at Georgetown University Medical Center leads the study.
The study’s senior investigator explained that during this moment, the neurons are still too busy processing one image but are already given more tasks to finish too quickly. This results in either one or both the images to not reach the person’s conscious awareness.
This means that though the eyes see the image and the brain processed the outcome, the image/s still doesn’t ‘register’ in your conscious awareness due to the “crash in visual processing”.
“Prior studies have shown that people are rather poor at detecting objects of interests that appear close together in time, even though the human brain can process up to 70 images per second. Our study shows a specific limitation of the visual system and explains why our consciousness cannot keep up,” Riesenhuber explained.
“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.”
To test their hypothesis, participants were asked to undergo a series of EEG experiments wherein they are shown images of natural scenes, streamed in short bursts at a rate of 12 per second. The participants were asked how many of the images they viewed contained animals; they were also asked to identify the animals they saw in the pictures.
The results of the study showed that the crash in visual processing happens when the brain is stimulated again with a second image, even if it did not have enough time to process the feed forward and feedback loop needed for the first image to be completed, Riesenhuber further explained.
“The feedback wave appears to be crucial for participants to actually become conscious of the stimuli their brains had processed in the ‘feedforward’ pass,” he added.
According to the scientists, this only proves that the brain has a limitation in what it could process within a select time period. They believe that this has a useful impact in how we view learning and attention.
“In addition to introducing a theory that explains the underlying reason for the lack of awareness, our study also shows how to avoid the neuronal signal ‘crash’ and increase awareness. When we experimentally reduced the interference between the feedforward and feedback portions of the two stimuli, we observed improved detection and categorization performance,” added the study’s lead author, Jacob G. Martin, PhD.
“Such findings are exciting because they could lead to novel methods for accelerating cognitive processing and learning in humans.”
How Do People See?
The eyes, specifically the cornea and lens, form an upside-down image of the object you see, putting this at the retina, the part of your eyes that’s located at the back. Once the image reaches the retina, it will be forwarded to the brain through the optic nerve.
For the image to be correct and processed right, the eye then rotates it another 180 degrees so the brain could see it right-side up.