University of Arizona doctoral degree candidate Jay Sanguinetti has authored a new study, published online in the journal Psychological Science, that indicates that the brain processes and understands visusal input that we may never consciously perceive. The finding challenges currently accepted models about how the brain processes visual information.
A doctoral candidate in the UA's Department of Psychology in the College of Science, Sanguinetti showed study participants a series of black silhouettes, some of which contained meaningful, real-world objects hidden in the white spaces on the outsides. Saguinetti worked with his adviser Mary Peterson, a professor of psychology and director of the UA's Cognitive Science Program, and with John Allen, a UA Distinguished Professor of psychology, cognitive science and neuroscience, to monitor subjects' brainwaves with an electroencephalogram, or EEG, while they viewed the objects.
"We were asking the question of whether the brain was processing the meaning of the objects that are on the outside of these silhouettes," Sanguinetti said. "The specific question was, 'Does the brain process those hidden shapes to the level of meaning, even when the subject doesn't consciously see them?"
The answer, Sanguinetti's data indicates, is yes.
Study participants' brainwaves indicated that even if a person never consciously recognized the shapes on the outside of the image, their brains still processed those shapes to the level of understanding their meaning.
"There's a brain signature for meaningful processing," Sanguinetti said. A peak in the averaged brainwaves called N400 indicates that the brain has recognized an object and associated it with a particular meaning.
"It happens about 400 milliseconds after the image is shown, less than a half a second," said Peterson. "As one looks at brainwaves, they're undulating above a baseline axis and below that axis. The negative ones below the axis are called N and positive ones above the axis are called P, so N400 means it's a negative waveform that happens approximately 400 milliseconds after the image is shown."
The presence of the N400 peak indicates that subjects' brains recognize the meaning of the shapes on the outside of the figure.
"The participants in our experiments don't see those shapes on the outside; nonetheless, the brain signature tells us that they have processed the meaning of those shapes," said Peterson. "But the brain rejects them as interpretations, and if it rejects the shapes from conscious perception, then you won't have any awareness of them."
"We also have novel silhouettes as experimental controls," Sanguinetti said. "These are novel black shapes in the middle and nothing meaningful on the outside."
The N400 waveform does not appear on the EEG of subjects when they are seeing truly novel silhouettes, without images of any real-world objects, indicating that the brain does not recognize a meaningful object in the image.
"This is huge," Peterson said. "We have neural evidence that the brain is processing the shape and its meaning of the hidden images in the silhouettes we showed to participants in our study."
The finding leads to the question of why the brain would process the meaning of a shape when a person is ultimately not going to perceive it, Sanguinetti said.
"The traditional opinion in vision research is that this would be wasteful in terms of resources," he explained. "If you're not going to ultimately see the object on the outside why would the brain waste all these processing resources and process that image up to the level of meaning?"
"Many, many theorists assume that because it takes a lot of energy for brain processing, that the brain is only going to spend time processing what you're ultimately going to perceive," added Peterson. "But in fact the brain is deciding what you're going to perceive, and it's processing all of the information and then it's determining what's the best interpretation."
"This is a window into what the brain is doing all the time," Peterson said. "It's always sifting through a variety of possibilities and finding the best interpretation for what's out there. And the best interpretation may vary with the situation."
Our brains may have evolved to sift through the barrage of visual input in our eyes and identify those things that are most important for us to consciously perceive, such as a threat or resources such as food, Peterson suggested.
In the future, Peterson and Sanguinetti plan to look for the specific regions in the brain where the processing of meaning occurs.
"We're trying to look at exactly what brain regions are involved," said Peterson. "The EEG tells us this processing is happening and it tells us when it's happening, but it doesn't tell us where it's occurring in the brain."
"We want to look inside the brain to understand where and how this meaning is processed," said Peterson.
Images were shown to Sanguinetti's study participants for only 170 milliseconds, yet their brains were able to complete the complex processes necessary to interpret the meaning of the hidden objects.
"There are a lot of processes that happen in the brain to help us interpret all the complexity that hits our eyeballs," Sanguinetti said. "The brain is able to process and interpret this information very quickly."
Sanguinetti's study indicates that in our everyday life, as we walk down the street, for example, our brains may recognize many meaningful objects in the visual scene, but ultimately we are aware of only a handful of those objects. The brain is working to provide us with the best, most useful possible interpretation of the visual world, Sanguinetti said, an interpretation that does not necessarily include all the information in the visual input.
Sanguinetti's study was funded by a grant to Mary Peterson from the National Science Foundation.
Daniel Stolte | University of Arizona
New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)
Reusable carbon nanotubes could be the water filter of the future, says RIT study
30.03.2017 | Rochester Institute of Technology
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences