Visual Illusion That May Help Explain Consciousness

Summary: A new visual illusion sheds light on redundancy masking and how we perceive our visual environment. The findings provide new insight into human consciousness.

Source: The Conversation

How much are you conscious of right now? Are you conscious of just the words in the centre of your visual field or all the words surrounding it? We tend to assume that our visual consciousness gives us a rich and detailed picture of the entire scene in front of us. The truth is very different, as our discovery of a visual illusion, published in Psychological Science, shows.

To illustrate how limited the information in our visual field is, get a deck of playing cards. Pick a spot on the wall in front of you and stare at it. Then take a card at random. Without looking at its front, hold it far out to your left with a straight arm, until it’s on the very edge of your visual field. Keep staring at the point on the wall and flip the card round so it’s facing you.

Try to guess its colour. You will probably find it extremely difficult. Now slowly move the card closer to the centre of your vision, while keeping your arm straight. Pay close attention to the point at which you can identify its colour.

It’s amazing how central the card needs to be before you’re able to do this, let alone identify its suit or value. What this little experiment shows is how undetailed (and often inaccurate) our conscious vision is, especially outside the centre of our visual field.

Crowding: how the brain gets confused

Here is another example that brings us a little closer to how these phenomena are investigated scientifically. Please focus your eyes on the + sign on the left, and try to identify the letter on the right of it (of course you know already what it is, but pretend for the moment that you do not):

Illusion 1. TCUK, CC BY-SA

You might find this a bit tricky, but you can probably still identify the letter as an “A”. But now focus your eyes on the following +, and try to identify the letters on the right:

Illusion 2. TCUK, CC BY-SA

In this case, you’ll probably struggle to identify the letters. It probably looks like a mess of features to you. Or maybe you feel like you can see a jumble of curves and lines, without being able to say precisely what’s there. This is called “crowding”. Our visual system sometimes does OK at identifying objects in our peripheral vision, but when those objects are placed near other objects, it struggles. This is a shocking limitation on our conscious vision. The letters are clearly presented right in front of us. But still our conscious mind gets confused.

Crowding is a hotly debated topic in philosophypsychology and neuroscience. We’re still not sure why crowding happens. One popular theory is that it’s a failure of what’s called “feature integration”. To understand feature integration, we will need to pick apart some of the jobs that your visual system does.

Imagine you are looking at a blue square and a red circle. Your visual system does not just have to detect the properties out there (blueness, redness, circularity, squareness). It also has to work out which property belongs to which object. This might not seem like a complicated task to us. However, in the visual brain, this is no trivial matter.

It takes a lot of complicated computation to work out that circularity and redness are properties of one object at the same location. The visual system needs to “glue” together the circularity and the redness as both belonging to the same object, and do the same with blueness and squareness. This gluing process is feature integration.

This shows a man and a brain
The brain is a mystery. Image adapted from The Conversation news release

According to this theory, what happens in crowding is that the visual system detects the properties out there, but it can’t work out which properties belong to which object. As a result, what you see is a big mess of features, and your conscious mind cannot differentiate one letter from the others.

New illusion

Recently, we have discovered a new visual illusion that has raised a host of new questions for fans of crowding. We tested what happens when three of the objects are identical, for example in the following case:

Illusion 3. TCUK, CC BY-SA

What do you see when you look at the +? We found that more than half of people said that there were only two letters there, rather than three. Indeed, follow-up work seems to indicate that they’re pretty confident about this incorrect judgment.

This is a surprising result. Unlike normal crowding, it’s not that you see a jumble of features. Rather, one whole letter neatly drops away from consciousness. This result fits poorly with the feature integration theory. It’s not that the visual system is detecting all of the properties out there, but just getting confused about which properties belong to which objects. Rather, one whole object has just disappeared.

We don’t think that a failure of feature integration is what’s going on. Our theory is that this illusion is due to what we call “redundancy masking”. In our view, the visual system can detect that there are several of the same letter out there, but it doesn’t seem to calculate correctly how many there are. Maybe it’s just not worth the energy to work out the number of letters with high precision.

When we open our eyes, we effortlessly get a conscious picture of our environment. However, the underlying processes that go into creating this picture are anything but effortless. Illusions like redundancy masking help us unpick how these processes work, and ultimately will help us explain consciousness itself.

Funding: Bilge Sayim receives funding from the French Agence Nationale de la Recherche (ANR), I-SITE ULNE, and the Swiss National Science Foundation (SNSF).

Henry Taylor does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

About this consciousness research news

Source: The Conversation
Contact: Bilge Sayim & Henry Taylor -The Conversation
Images: The lead image is adapted from The Conversation news release. The illusion images are credited to  TCUK, CC BY-SA

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  1. I had a dream recently that really made me question some of this. In the dream I walked past an open room door on my left side. While looking into the room as I passed I noticed it was a bedroom. It had another door directly across in the same straight line of direction. I was walking straight with the bedroom door in my left eye’s line of peripheral vision. I noticed there was a refrigerator right next to the open door directly across from the one on my left I was passing. I realized that it would not make any sense for a refrigerator to be in a bedroom in that second as I was passing I never took my left eye off the refrigerator. With it still in my left eye’s sight I went to turn my head fully twords it and the refrigerator disappeared. As I realized it shouldn’t be there I was also aware that I was dreaming. A majority of the time I am aware that I am dreaming and to some extent can control my actions but not the dream itself. I had a full seemingly conscious conversation with my friend in a dream. Where I can swear we both knew it was a dream. I never asked him about it just because I don’t ever see him in my real life anymore. Very strange and interesting.

  2. The title of the article is misleading. The subject of the article is not consciousness but peripheral vision. Consciousness is a whole different issue. Peripheral-vision limitations are well-known. More research will certainly improve our understanding and the results would lead to many new applications. However, consciousness, as in self awareness is a far more intriguing and exciting subject that this article mistakenly alluded to.

  3. The crowding Effect is well-known and doctors have to deal with it in eye exams. When you put something in the peripheral visual field it has nothing to do with the crowding effect. What happens in the peripheral of the retina there are mostly rods that are not sensitive to color and when we bring it to the center of our vision the Fovea centralis’ cones pick up colors and details far better than the rods The predominate in the peripheral retina

  4. Interesting article and very interesting comments. I was an art professor for over thirty years teaching drawing and painting. Many of my intro drawing students took the course to fulfill their Humanities requirement, some were art majors.

    The most continuous feedback that I received from studies (of all ages) was: “I have no idea what I saw before I took your class but everything looks different now.” That was the mantra.

    I literally had to teach the students how to “see”. From black to white to color; from basic shapes to geometric solids; from thin and thick straight lines to thin and thick curvilinear lines; to when the sun hits the closest on a part of an object a highlight on the object is created; to the length, width, depth and intensity of a shadow cast by an object that blocked the light source is determined by the angle of that light source and by the opacity of the object. Amazement and enjoyment and surprise came from all of my students that their cone of vision only allowed our brain to clearly see what we were focusing our eyes upon.

    Many students never realize what they were missing when they looked at something, Awareness of what we see brings a deeper appreciation and a better understanding of everything and everyone around us. Scientific research about seeing also helps us better understand how our body works. Thank you scientists.

  5. As far as i can see this has to do with vision and the processing of it, not conciousness.

  6. All of these erroneous determinations regarding the bodies to the right of the plus sign seem to have more to do with unfocused eyes and simply not seeing clearly in the first place.

  7. Nothing beats the Cheshire Cat illusion. Motion in the peripheral rod retina masks or erases central foveal cone consciousness.

  8. Um…wth. State, you dimwits, are you speaking about abnormal or average brains ? or, lol,are we now at the point where there is no discernible difference ? Listen up.. The purist, non damaged brain of all humanity is far more superior and high functioning than any of you dweebs can imagine, let alone be condemned to CONFUSION towards visual illusion. The brain does not falsify, you do.

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