Study: Your brain sees things you don't

November 13, 2013
Davi Vitela dons the cap used to take EEG scans of her brain activity while she views a series of images in Sanguinetti's study. Credit: Patrick McArdle/UANews

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 was processing the 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."

Study: Your brain sees things you don't
Sanguinetti showed study participants images of what appeared to be an abstract black object. Sometimes, however, there were real-world objects hidden at the borders of the black silhouette. In this image, the outlines of two seahorses can be seen in the white spaces surrounding the black object. Credit: Jay Sanguinetti

"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.

Substantial previous research has linked the N400 waveform from EEG scans with brain processing of meaning. It's appearance in EEG scans of participants in Sanguinetti's study indicates that their brains recognized hidden silhouettes in the images the participants were shown, even if the subjects themselves were never consciously aware of them. Credit: Jay Sanguinetti

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.

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1 / 5 (3) Nov 13, 2013
Olfaction spontaneously highlights visual saliency map http://www.ncbi.n...23945694 ""...we reason it was spontaneous binding between congruent olfactory and visual information [25] that formed a multimodal saliency map where the visual object with added olfactory presence gained increased perceptual saliency."

Like any other animal, olfactory/pheromonal input is paired with visual and other sensory input from before birth, and unconscious associations are made throughout life. To understand the relative salience of sensory input in experiments like this, the researches need only pair an incongruent odor with the visual stimulus and measure the increase in the time of the measured unconscious response.

See for example: http://www.jneuro...abstract
1 / 5 (2) Nov 14, 2013
I consider my brain among other body parts to be me, so the title of the article is nonsensical. What "my brain" is doing is simply what I am doing, and even that is redundantly expressed because what I am is just the doing.

The separation of mind and the "hardware" of the mind so to speak, is simply a dualist argument, and under such ideas the mind escapes out of reach until finally you have to conclude that there is no mind in a person - just unthinking unfeeling non-understanding physical phenomena and the "you" is nowhere to be found. There is no intelligence, there is no will, and there is no you.

If on the other hand you understand that what you are is what you is, then there is no problem. It doesn't matter where you draw the line, because whatever you include in the doing that is you, it's all there. It's just a matter of practicality.
3 / 5 (2) Nov 14, 2013
The Mind's Eyes: Human pheromones, neuroscience, and male sexual preferences is available as an archived author's copy at

"The across-species genetic conservation of intercellular and extracellular chemical communication enables unicellular and multicellular organisms to functionally distinguish between self and non-self. Non-self olfactory/pheromonal input from the social environment elicits a vertebrate neuroendocrine response. The organization and activation of this neuroendocrine response modulates the concurrent maturation of the mammalian neuroendocrine system, the reproductive system, and the central nervous system during the development of sexual preferences that may be expressed in sexual behavior. Psycho-physiological mechanisms for the development of these sexual preferences include focus on unconscious affects that are detailed in reciprocal cause and effect relationships."

None of this matters to Eikka.
3.7 / 5 (3) Nov 14, 2013
In layman's terms, we have evolved a sense of focus, or attention, that allows us to process input that is relevant to both our survival and the task at hand. We subconsciously receive a lot of information, but consciously only use what is pertinent. For example, you can carry on a conversation at a large party while never bothering to process large amounts of the extraneous audible input you are hearing around you.

To truly experience how much you might be ignoring, you might try ingesting a psychoactive substance such as LSD or Psilocybin. Focus will give way to periods of total input. It is both overwhelming and insightful.

Charlie Rose conducted an excellent series of interviews with prominent neuro-specialists, titled the "Brain Series", where he discusses the latest findings and advancements in their fields. It is amazing and a worthwhile look-up.
1 / 5 (2) Nov 14, 2013
"None of this matters to Eikka."

It's simply another point of view. The organism as the self isn't really defined without its surroundings, so there's no hard division between you and everything else. What is you is just a matter of where you want you to end and something else to begin. It doesn't really end at any point, but we can't talk about you in a useful way unless we make the distinction.

If you lift a bacterium out of a petri dish and perfectly isolate it from everything to find out exactly what belongs to it, it instead ceases to be. Metaphysically speaking, it's not in this reality anymore so you can't say "this and only this is it". You wouldn't know what you're talking about.

1 / 5 (1) Nov 14, 2013
"To truly experience how much you might be ignoring, you might try ingesting a psychoactive substance such as LSD or Psilocybin. Focus will give way to periods of total input. It is both overwhelming and insightful."

Although some would argue that what you're experiencing there is not total input, but just the upheaval of your brain signals into a bunch of garbage that you mistake as something profound.

Psychedelic drugs are more like sticking a screwdriver into a running computer. It's far more likely that instead of producing some novel information, all you manage to cause is a program glitch. All your thoughts and memories carry a kind of cue that records the context they exist in, like "this is a memory" and "this is happening now", and "this is true/false". When you mix the thoughts and the cues, you get crazy stuff like deja-vus and spiritual enlightenment over the word "spoon".

Just like in a dream where the ultimate answer is the smell of burnt almonds.
1 / 5 (1) Nov 14, 2013
Eikka: "The organism as the self isn't really defined without its surroundings, so there's no hard division between you and everything else. What is you is just a matter of where you want you to end and something else to begin. It doesn't really end at any point, but we can't talk about you in a useful way unless we make the distinction."

Self vs non-self recognition is a function of the de novo creation of olfactory receptor genes and pheromones in species from microbes to man.
2 / 5 (2) Nov 14, 2013
"Self vs non-self recognition is a function of the de novo creation of olfactory receptor genes and pheromones in species from microbes to man."

What's that got to do with anything I said?

It's simply a mechanism by which the organism draws the line between it and other for purposes of survival. It's still an arbitrary subjective distinction, because the organism isn't anything without its environment which it is a part of.
3.7 / 5 (3) Nov 14, 2013
"Although some would argue that what you're experiencing there is not total input, but just the upheaval of your brain signals into a bunch of garbage that you mistake as something profound."

The insight I am referring to is a strictly academic experience of being able to observe more of the sensory input that is present by limiting the effect ordinarily imposed by the process of conscious selective attention. We are normally not aware of the brain's constantly active filtering of information to facilitate focus.

What I speak of has nothing to do with assigning some meaning or higher purpose that can also accompany such an investigation. That is often another aspect of the experience, and both are revealing of how the conscious mind functions.

I might also mention that you appear to have some indoctrination that limits your ability to comprehend what may be intellectually relevant than you think. You dismiss and condemn from a position of unfamiliarity and acquired bias.
4 / 5 (4) Nov 14, 2013

It would not surprise me if he would equally dismiss the effects of sensory deprivation, another interesting insightful exercise. I've had the good fortune to experience both. Each offer a unique place to observe what your "everyday" mind-brain normally keeps in stealth mode.
1 / 5 (1) Nov 14, 2013
The posted report here simply asserts a brain or mind that 'constructs' it's input.
Neuroscience calls flows of information "down" or "bottom-up" processes if stemming from sensory sources.
That is not the case here.
The flow of information is called "up" or "top-down" process - an 'internal' process.
No restriction is placed on this "top-down" process, this excludes 'awareness' as well.

The "crazy stuff" (artificially induced) can occur naturally as well without artificial means. For example, hearing motion is labeled a form of synesthesia. Quite normal.

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