Primrose Field

July 28, 2014

This particular optical illusion is called the Primrose Field. If you take some time to stare at the picture it feels like it is moving like a wave.  In clearer terms it can be described as a waving motion illusion.  Personally, I have always been fascinated by this illusion, as it is amazing how patterns, shapes, and colors can be used to play a trick on the human mind.  One thing that has always interested me is how things that are stationary seem like they are moving.  I found many illusions similar to this one on the websites provided, but I believe that this one did the best job of displaying a wavelike motion.

The neurological basis of how us humans interpret illusions stems all the way back to our days growing up as children.  When we learn to analyze images when we are little, we soon learn to interpret different objects and label them automatically.  Now, I as I found out on a neurological blog the term used to define the trick that optical illusions play on our eyes is called camouflage.  As we see an illusion like the one we see above we attempt to associate it with something that we over time have stored in our brain.  However, the illusion is able to “overwhelm” us.  Our eyes and brain do not connect and read each other. Optical illusions are able to fool us by overwhelming our brains with images, color, lighting, and perspective.  The illusion pictured above uses red and white colored dots along with a checkered pattern in order to trick us.  By drawing the patterns at different angles we get fooled.  My mind originally connected this illusion to a quilt, so when I stared at it for a while I thought I was going crazy when I saw the image move.

 

 


Ambiguous Images

July 28, 2014

Ambiguous Images

Ambiguous Images

-Heather Forbes

Example

220px-German_postcard_from_1888

—Is this woman young or old?

—What do you see in this image?

About Ambiguous Images

—Images or objects that can be interpreted as different things by different people.

Do you see a face or something else?

Do you see a duck or something else?

What Happens When We View an Ambiguous Image?

—When we see an ambiguous image, we are usually presented with two ways of seeing something.

—By nature, we only see one at first.

—It usually takes time or prompting to see the other version/image.

—At this point, we are no longer able to see the second image.

—It is impossible to see both interpretations at the same time.

 

How Does this Happen? 

—We first see an ambiguous image in mid-level vision.

—That means we are trying to make out exactly what it is.

—When we identify which option we see, that is called “higher-level vision.”

—We try to perceive lines and corners to tell what something is.

—We try to organize things into groups.

—Using Gestalt’s rules, we attempt to organize what we see based on proximity, similarity, and continuity, among other things.

Behind the Scenes

—A study regarding the effects of retinal perception of ambiguous images lead to…

—Changes perceived at the lateral occipitotemporal junction, corresponding to the human motion complex.

—Perceptual switches that included bilateral inferior frontal lobe regions and the right inferior parietal lobule.

—Activations related to the preparation and execution of motor reports, e.g., in the hand representations of the left primary sensorimotor cortex and the cerebellum as well as in the supplementary motor area.

—

—Source: http://www.pnas.org/content/104/1/323.full

 

In Other Words… 

—Seeing ambiguous images causes areas of the brain which cause motion to be activated.

—As a result, we often feel confused and try to look back and forth at parts of the image.

—But visual illusions are not as they seem…

—Because often what we see is not really there.

—Because of the brain’s speed, shortcuts are taken so that we only see some parts of the image we are looking at.

—Our visual system approximates some components of an image.

What Can We Learn About the Visual System?

—The main takeaway from ambiguous images is that the eyes are not alone in forming the images that we see.

—They interact closely with the brain.

—But, because the brain must interpret things, it often has difficulty with some colors and shapes.

—So what we see is not necessarily all that is there… like how some may see a rabbit and others a duck…

 

SOURCES:

—http://www.academia.edu/849554/THE_DEVELOPMENT_OF_AMBIGUOUS_FIGURE_PERCEPTION

—http://en.wikipedia.org/wiki/Ambiguous_image#Perceiving_the_image_in_mid-level_vision

—http://www.pnas.org/content/104/1/323.full

—http://www.pbs.org/wnet/brain/illusions/

 

It’s All How You Look at IT!

Salvador Dali and M.C. Escher frequently employed this mind trick!

This site has some cool examples to try for yourself!

http://www.world-mysteries.com/illusions/sci_illusions3.htm

 


The CheckerShadow Illusion

July 28, 2014

checkershadow_illusion4med

In this illusion, it appears that box A and box B are different shades of gray, but in reality they are the same color.  This can be proved with the picture below.  Two lines that are the same color gray as boxes A and B are shown, connecting the two.  Here, it becomes clear that they are the same color

.checkershadow_double_med

 

You can also print out the image and cut the squares out to prove that they are in fact the same color.

There are a few reasons as to why this illusion works.  When the brain’s visual system is trying to determine the color of boxes, it absorbs information about the entire board, not just the individual square.  Box A is darker than the surrounding boxes, so there is great contrast and the visual system perceives the square as darker than it really is.  The opposite goes for Box B; it is lighter than the surrounding squares, so the visual system perceives it as lighter than reality.  Also, Box B is in the shadow cast by the green cylinder.  The human visual system not a good physical light meter, and because the fuzzy shadow is cast over sharp intersecting lines, it does not perceive much light gradient.  Because of the different contrasts, the visual system assumes each box as light or dark given this picture.  They look different because of their surroundings, and the visual system interprets all of the information together, not one box at a time.  This illusion shows that the visual system processes things as a whole, and also it want everything to fit nicely as either light or dark, in this case.  The neurons of the retina and the occipital lobe perceive the “main idea” of the image and do not dwell on the specifics.

This illusion was made in 1995 by Edward H Adelson, a professor at MIT.  He points out that the illusions shows the success of the visual system because it perceives the import aspects of the image, which is it’s purpose.

Here is the link to Adelson’s page on this illusion:

http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html


Squidward Tentacles

July 28, 2014

squidward the bae

Despite his name, Squidward Tentacles is actually an octopus! However, Squidward’s nervous system would be very different from that of a real octopus due to his unique abilities in the Bikini Bottom. Since he stands straight and can walk, Squidward would have to have a spine (real octopuses are invertebrates). Additionally, his upright stance would imply that the spinal cord and brain stem would be at a 90 degree angle to the forebrain.

Unlike a typical octopus, Squidward can communicate with others-whether it be yelling at neighbors Spongebob and Patrick or taking an order at the Krusty Krab. Therefore, regions of the forebrain involved in generating language would be much larger in comparison to a regular octopus. Furthermore, Squidward’s brain would be larger in areas regarding social cognition, such as the frontal lobe. Squidward Tentacles’ ability to play the clarinet and freely use his tentacles like arms and legs indicate that the would have an enlarged cerebellum along with a larger motor cortex. This is also supported by how he can memorize music, read, and do other activities like a human.

Although Squidward is an octopus, his extraordinary gifts are a result of differences in his nervous system compared to that of a typical member of the species.


Ambiguous images

July 28, 2014

220px-German_postcard_from_1888

In this optical illusion you can see both the young lady and the old woman. These illusions are famous for for using multistable perception. Multistable perception occurs when an image is able to provide multiple, yet stable, perceptions. Some other examples are the Rubin Vase and the Rabbit/Duck.

The brain uses middle vision to make the picture into a distinct and recognizable object. The brain does this by trying to find the edges, whether that be of a persons facial structure or a simple object. The visual system then connects the image as a whole.

For a more in depth view of this here is a quote from the first source linked:

“ We used functional MRI to measure brain activity while human observers reported successive spontaneous changes in perceived direction for an ambiguous apparent motion stimulus. In a control condition, the individual sequences of spontaneous perceptual switches during bistability were replayed by using a disambiguated version of the stimulus. Greater activations during spontaneous compared with stimulus-driven switches were observed in inferior frontal cortex bilaterally. Subsequent chronometric analyses of event-related signal time courses showed that, relative to activations in motion-sensitive extrastriate visual cortex, right inferior frontal cortex activation occurred earlier during spontaneous than during stimulus-driven perceptual changes. The temporal precedence of right inferior frontal activations suggests that this region participates in initiating spontaneous switches in perception during constant physical stimulation. Our findings can thus be seen as a signature of when and where the brain “makes up its mind” about competing perceptual interpretations of a given sensory input pattern.”
This optical illusion, or ambiguous image, exploits the graphical similarities and other properties of the visual system, like the interpretation between two or more different images.

Sources:
• http://www.ncbi.nlm.nih.gov/pubmed/17190824
http://en.wikipedia.org/wiki/Ambiguous_image#Identifying_and_resolving_ambiguous_images


The Müller-Lyer Illusion

July 28, 2014

In the optical illusion, Müller-Lyer illusion, the audience is asked to find the line that appears to be the longest or the shortest in the following picture. For most people, the line with the ends of the arrow protruding outward appears to be longest, while the line with the fins pointing inward appears to be the shortest. However, in reality, all three lines have exactly the same length. 

Screen Shot 2014-07-28 at 9.33.51 AM

There are many explanations to how the Müller-Lyer illusion works in our brain. According to Richard Gregory(a psychologist), this illusion mainly occurs due to a miscalculation of size constancy scaling in our brain. Most of the times in our 3D world, size constancy allows humans to determine whether a person is tall or not without having to depend much on their physical location. However, when we apply this method into 2D, miscalculations can result- causing our brain to sense that the same length of arrows are actually different in sizes. 

Another theory, presented by R.H.Day, proposes that this illusion occurs mainly due to conflicting cues. He claims that our ability to determine the length of the lines depends on the actual length of the line itself (the overall length of the figure). Since the total length of the three figures differ, this causes our brain to see one line longer than the other. 

Other researches believe that the illusion also has to do with depth perception.

The Müller-Lyer illusion illustrates how the brain reflexively determines and processes information about length and size. This also hints that optical illusions can represent what our human brain wants to perceive. 

If you want to test your abilities for the Müller-Lyer illusion, visit this website:

http://bcs.worthpublishers.com/psychsim5/Visual%20Illusions/PsychSim_Shell.html


Rubin’s Vase

July 28, 2014

Rubin's Vase

In Rubin’s vase, one can see either two “black-colored” faces looking at each other or a “white-colored” vase. It is impossible for the eye to interpret both pictures at one time because the bounding outline will only belong to one of the figures, appearing to fit in with the formless background.

The brain usually picks out images by the contours of the objects that are being seen. This lets the brain create depth and relationships. The surrounded object is the “figure” and the surrounding object which is usually a background is the “ground”. But in this case, the surroundings are easily confusable with the surrounded. When the brain sees this picture, it begins “shaping” what it sees. This “shaping” overrides the feature recognizing processes of the faces and the vase. To the brain, each figure, in this case the faces and the vase, makes sense in isolation of each other but disagreements are formed when both are attempted to be pictured at one time.

This tells use that the brain recognizes the contours or outlines of the pictures we see. In order to pick out an object in the picture, the outline is seen. Rubin’s vase attempted to trick the brain by giving us two “figures” in one with the same outline. This is why it is impossible for the human eye to see both figures at once.

It also shows us that we do need basic cortical processing to understand Rubin’s vase as well.

This kind of picture can be created with an “object (2D)” whose outline is the same with the other. There should be no texture to the picture and it should be flat.

Rubin’s Vase is an ambiguous picture/ground  illusion.


The Spinning Dancer

July 28, 2014

This illusion, known as the spinning dancer, can be viewed as turning either clockwise or counterclockwise.

The first time that I looked at this, there was no doubt in my mind that the woman was spinning clockwise. I could clearly see her left foot on the ground and her right crooked arm approaching me from the right. When I realized she was supposed to be able to turn both ways, I told myself: “It’s all in your head. She’s going counterclockwise right…now.” Needless to say, that tactic did not work out so well.

It turns out that this succeeds as an illusion because of lack of visual cues of depth. Really, how you view this illusion is based on how you assume the woman is standing when you first look at her.

Below is a frame by frame version of the spinning dancer. The first time you glance through this, convince yourself that her left foot is on the ground, and her right is in the air. She is starting with her back facing you. It looks like she is going clockwise, right? Now convince yourself that her right foot is on the ground, and it’s the left one that she has picked up. This time, she starts facing towards you. She’s going counterclockwise!

Spinning Dancer Frames

This illusion tells us that our visual system is actually able to construct a reasonable mental image of the world around us by making assumptions when we have a limited amount of information. Typically our assumptions are valid because there is only one right way to interpret a given set of stimuli in nature. However, when our brain is presented with stimuli that could result in two different, contradicting, yet valid interpretations, our brains pick one. Later, it could pick the other. It is still not completely understood what factors affect this decision making process, and how conscious effort allows us to control this aspect at will.

Here’s the trick that I use to be able to control the spinning dancer. If she is moving clockwise to you, and you want her to move counterclockwise, focus on the shadow of her lifted foot when it is on the left of your screen. If you need to, cover the rest of her body.  Catch the foot on its path as it moves from the left, towards you, off the screen, and away from you to the right. If it helps, rotate your finger in a circle until you undoubtedly see the foot travelling in this pattern. If you look at the whole body, it should now be moving counterclockwise.

The opposite is also true. If you want her to go from counterclockwise to clockwise, catch her foot when it is on the right side of your screen, and visualize it coming towards you and then away to the left. Repeat this cycle until the foot and the person are both moving clockwise.

As I mentioned earlier, I started off utterly convinced that it was impossible for her to switch directions. Now, after some practice, I can easily see her alternate as often and as quickly as I want to! This too says something about the adaptability of the brain, and how previously weak connections can be strengthened through repetition.

Interestingly enough, bistability – something that can rest in either of two states – is not just a visual phenomenon. One auditory example is the tritone paradox. This tune can either be heard as ascending or descending. Can you hear both?

Yet another auditory example which I find incredibly cool albeit creepy is that of phantom words. In each track, either two one-syllable words or a single two-syllable word is repeated over and over again. The brain seems to construct a meaning from these sounds which is not necessarily there.  Interestingly enough, people tend to hear words about what is currently on their minds. For example, people who are dieting have reported hearing words that are related to food. Yet, while listening to the exact same sounds, someone who is stressed may hear words having to do with stress. What do you hear?

Bonus: This illusion is called motion aftereffect, where viewing a moving stimulus while being stationary can later cause a stationary stimulus to appear to be moving. I think that this is because of our brain’s predictive perception, as explained by Mark Changizi in the provided TED talk. Our brains create a perception of the world 0.10 seconds in the future, rather than of the moment when light hits our retinas. Because we have been staring at a moving stimulus for an extended period of time, abruptly moving to a stationary stimulus would not change the fact that our brains continue to expect motion.


The Brain of a Hippogriff

July 23, 2014

 Hippogriff

If you haven’t seen Harry Potter you may not know what a hippogriff is. In the third book of the series the hippogriff is a pet of Hagrid’s, and his name is Buckbeak. A hippogriff is a cross between a horse and an eagle; therefore his brain is a cross between these two animals. Buckbeak has four legs, but this is the only similarity he has to a horse. The rest of his characteristics are closer to those of a bird. We see this with his ability to fly, as well as the fact that he finds shelter in the form of nest. So we can assume that his brain would be closer to that of a birds than a horse. Birds have very large cerebral hemispheres compared to the rest of their brain, and so this would be seen in a hippogriff. Their cerebellum would be large as well since they have very good reflexes and coordination, which they would receive from both birds and horses.

Bird Brain:                                                                                    

 bird brain

Horse Brain:

horse brain

Hippogriffs are intelligent creatures. Although they are not able to speak themselves, they are able to understand language. They are also able to experience emotions. Therefore, I would say that they would have a large cerebral hemisphere, as well as a substantial amygdala. Since hippogriffs are quite intelligent creatures that understand language they rely more on their visual and auditory senses meaning that they would have a larger optic lobe and cerebral cortex, and a smaller olfactory bulb, as they rely less on smell.

Sources:

http://harrypotter.wikia.com/wiki/Hippogriff

http://www.docstoc.com/docs/92642796/NER-HORSE-BRAIN-Left-lateral-view-cerebral-hemisphere-medulla

http://people.eku.edu/ritchisong/birdbrain.html