What I would like you to do is to find a topic from the chapter you read for Monday that you were interested in and search the internet for material on that topic. You might, for example, find people who are doing research on the topic, you might find web pages that discuss the topic, you might find youtube clips that demonstrate something related to the topic, etc. What you find and use is pretty much up to you at this point. But use at least 3 sources.
Once
you have completed your search and explorations, I would like you to
say what your topic is, how exactly it fits into the chapter, and why
you are interested in it. Next, I would like you to take the information
you found related to your topic, integrate/synthesize it, and then
write about it. At the end, please include working URLs for the three
websites.
Once you are done with your post make list of the terms and terminology you used in your post.
Let me know if you have any questions.
The topic I chose to find out more about is anamorphic art. There are two main forms of this type of art: perspective or oblique, and mirror or catoptric. According to Wikipedia, examples of perspectival anamorphosis dates back to the early Renaissance of the 15th Century and examples of mirror anamorphosis art was first created in the late Renaissance of the 16th Century. With mirror art, a cylindrical mirror is used to transform a flat image into a three-dimensional picture. The anamorphosis process diffuses the scene and images appear undeformed. I had not realized that the earliest known example of perspective anamorphosis is Leonardo da Vinci’s Leonardo’s Eye, of 1485. In 1685-1694, Andrea Pozzo painted the dome and vault of the Church of St. Ignazio in Rome. He was commissioned to paint the ceiling to look like a dome, because of complaints of blocked light by the monks. The ceiling is actually flat, but appears to look like a dome had been constructed. The term anamorphic art is Greek and refers to realistic art that is distorted and reformed by its reflection and appears to be magical and mysteriously three-dimensional. There are many examples of anamorphic art on the Internet today. Some are so realistic it boggles the mind and really makes a person study the drawing. It is interesting to see some of the artist perspective in painting these masterpieces.
Anamorphic art relates to this chapter with the use of pictorial depth cues and pictures. Interpretation of a three-dimensional object is portrayed and drawn on a two-dimensional surface or canvas. The retina views the image; we see depth in the image or photo.
TERMS: anamorphic art, anamorphosis, pictorial depth cues, undeformed, three-dimensional, two-dimensional
http://www.youtube.com/watch?v=8owCtUTaMd0
http://en.wikipedia.org/wiki/Anamorphic_art
http://en.wikipedia.org/wiki/Andrea_Pozzo
Did not know that. I hadn't seen that illusion before either. Cool.
The topic I found the most interesting from chapter 6 was binocular summation and stereopsis. I enjoyed learning about this concept because I like learning about the differences between varying species, especially when it comes to survival advantages and disadvantages. Binocular vision means using two eyes together to see the world. There are many advantages to having two eyes compared to one. It provides an organism with a spare in the event one is damaged or destroyed.It gives binocular summation in which the ability to detect faint objects is enhanced. Binocular summation means that the threshold for detecting a stimulus is lower with two eyes than with one. When trying to detect a faint stimulus, it’s statistically beneficial to have two detectors instead of one. It can also give stereopsis in which parallax provided by the two eyes' different positions on the head give precise depth perception.
Prey animals have their two eyes positioned on opposite sides of their heads to give the widest possible field of view. The eyes often move independently to increase their visual field. Predatory animals have both eyes positioned on the front of their heads, allowing for binocular vision and reducing their field of view in favor of stereopsis. Not all predatory animals have forward-facing eyes, like whales, and some non-predatory animals have forward-facing eyes like bats and primates. In the latter of these animals, fine depth perception is needed to obtain food. Binocular vision improves the ability to pick a certain fruit, or particular branch, on a tree. These are beneficial to the organism’s likelihood of survival.
There are differences between the visual fields of predator organisms and prey organisms. A prey animal’s visual field is much larger than a predator’s field of vision. For example, a rabbit’s visual field is 360 degrees, and they can even see straight up above them and down to the ground on the left and right, but not underneath their nose and mouth. It’s like a planetarium dome. In contrast, a human’s visual field is like a windshield. It only extends about 190 degrees from left to right in front of them. Of those 190 degrees, both eyes cover about 110 degrees. Unlike rabbits, humans’ visuals fields only extend 60 degrees up and 80 degrees down. These differences allow predators to see small, quick animals and objects in front of them to catch and eat. Prey animals with dome-shaped visual fields are better equipped to see all around them to avoid getting caught, and becoming a meal for a predator. I found a website with images of the different visual fields of organisms, which was helpful to me because I think visual images enhance the understanding of concepts.
Terms: binocular summation, stereopsis, binocular vision, visual field, parallax, depth perception, stimulus, detectors, field of view
Sources:
http://en.wikipedia.org/wiki/Binocular_vision
http://estebanfj.bio.purdue.edu/papers/AB_2011.pdf
http://www.google.com/search?q=human%27s+field+of+vision&rlz=1T4ADFA_enUS426US428&gs_upl=0l0l5l71635lllllllllll0&um=1&hl=en&tbm=isch&source=og&sa=N&tab=wi&gs_sm=3&oq=human%27s+field+of+vision&aq=f&aqi=g-S1&aql=
http://www.google.com/search?q=rabbit%27s+field+of+vision&rlz=1T4ADFA_enUS426US428&gs_upl=0l0l5l71635lllllllllll0&um=1&hl=en&tbm=isch&source=og&sa=N&tab=wi&gs_sm=3&oq=rabbit%27s+field+of+vision&aq=f&aqi=&aql=
Cool post. There's actually a new theory out about binocular vision by Mark Changizi. You should check it out.
The topic that I found most interesting from the chapter was anamorphic art. This form of art involves putting a 3-D image onto a 2-D surface that only becomes distinguishable what the picture is of when viewed from a certain point. The first person to do this form of art was Leonardo da Vinci in 1485. He did a form called perspective anamorphis. Another form of anamorphis is called mirror anamorphis. In this form a mirror is placed by the 3-D image. The artist replicates the image from the mirror onto the 2-D surface. The earlist forms of this type of anamorphis date back to the late 16th century. The word anamorphic comes from the Greek words ana-meaning back or again and morphe-meaning shape or form. Today, many artists pratice this form of art on the sidewalk. Julian Beever is a popular anamophic artist who sometimes even puts real people into her side walk art to mess with people minds even more. This relates to the chapter because anamorphic art really shows the extent that your eyes can play tricks on you. The pictures have pictorial depth cues that trick us into thinking that the side walk is actually 3-D. Some pictures also incorporate aerial perspective in which objects appear distant when they are hazey and less distinct.
Terms:Anamorphic art, relatice depth cues, aerial perspective.
http://en.wikipedia.org/wiki/Anamorphosis#Impossible_objects
http://www.julianbeever.net/
http://www.rense.com/general67/street.htm
The third and fifth ones down are my favorite.
I saw this sidewalk art in the last series of posts. Pretty cool stuff.
I was interested in the physiology of stereopsis, and how visual disparity creates depth with the 2-D perception of the retina. This is extraordinarily important for vision because, in a stationary being, visual disparity is the only way to create depth from the 2-D input of the retinal field. The book explains the basics well enough, but I delve deeper into the research to get a more accurate and expansive knowledge of the physiology of stereopsis.
The reason why your depth perception is enormously hindered by having only one eye is because of visual disparity. Each eye takes in a snapshot of the physical world; however, each eye is separated by a few inches, and this creates small differences in the snapshot of each retina. These differences are called visual disparity. Neurons on the left side (and right side for that matter) of each eye are separated until the primary visual cortex (V2), where these neurons converge. It is here int the PVC that binocular vision arises. Visual disparity is sensed by the brain due to the neurons being clustered according to their interocular position differences. With a converged mental map of the physical world, differences between the two retinal fields are more easily sensed.
However, the perception of depth is only relative; not absolute. While being stationary, the brain uses past experiences of the physical world to create guesses of the present environment. With movement, the stimuli can be more accurately portrayed in the mental spacial field, and the guesses made by the brain become more accordant to the actual environment.
Terms: physiology of stereopsis, visual disparity
https://docs.google.com/viewer?a=v&q=cache:9tdmR2enHaIJ:citeseerx.ist.psu.edu/viewdoc/download?doi%3D10.1.1.126.7868%26rep%3Drep1%26type%3Dpdf+&hl=en&gl=us&pid=bl&srcid=ADGEESh_kSgB18nKq3YXbBWEtFfd9A31JFefuHnpNHgX9xZqRXPEs5T5Vq1FJW8K6gKiosVTlXNSirGF38yhC_3mM6aBxrpdNxnZSyoeFaFpLQnqt1u9vIakmnNxPKkoKW5suUBcRHmS&sig=AHIEtbReWz6MW_JeUwIW2GxCKwLfCZfeig&pli=1
http://www.hms.harvard.edu/bss/neuro/bornlab/lab/papers/ponce-born-stereopsisprimer-currbiol2008.pdf
http://www.mdlinx.com/neurology/news-article.cfm/2346435/
I like that you have good sources from good authorities on the topic (harvard, etc.).
I decided to discover more about the eye disorder called strabismus. Simply put this is the medical term for people who are crossed eyed. This is a condition when both eyes do not look at the same place or area at the same time. It occurs when one eye is turned out, inward, upwards, or downwards, while the other eye is in another straight-forward position. This is usually caused by poor eye muscle control or a high amount of farsightedness. When one eye deviates inward it is called esotropia, when one eye deviates outward it is called exotropia. Furthermore, individuals with strabismus may also experience something called suppression. This is when the brain suppresses the image in either the right or left eye and it is simply not perceived by the brain.
If strabismus is left untreated, the eye that the brain ignores will never see well. This loss of vision is called amblyopia or lazy eye. Most of the time though the problem has to do with muscle control, and not with muscle strength. If the eye lacks control of the muscle in the effected eye, it will have a hard time taking both eyes to the same gaze point and will prevent proper binocular vision, which in turn will effect depth perception. Medically speaking, strabismus is either caused by cranial nerves or a lesion. A person with strabismus may also have intracranial pressure, which can be particularly damaging to the brain because of swelling.
Treatments for this eye disorder, depending on the severity of the onset, can be corrected using an eye patch on the dominant eye and/or vision therapy, to the extent of surgery to correct the issue. Surgery does not correct the vision, rather it will align the eyes by shortening, lengthening the position of one or more of the eye muscles. The procedure can mostly be done in an hour, but a week of recovery is needed.
http://en.wikipedia.org/wiki/Strabismus
http://www.nlm.nih.gov/medlineplus/ency/article/001004.htm
http://www.aoa.org/x4700.xml
TERMS: strabismus, esotropia, exotropia, suppression, amblyopia, binocular vision
There's also some work being done to make the other eye work more (patching) which is pretty interesting.
Projective geometry
The process of projective geometry is how an object is projected onto a surface. The first example of this that came to my mind is new elmo’s that are used in classrooms. These are revolutionary in projective geometry. How it works is similar to that of a projector, those noisy things that teachers used in grade school to show an image to the class. These catch with these projectors is that everything has to be printed onto these transparent sheets in order to be used properly on a projector. The elmo allows teachers to put anything on the projection screen. What a great tool and use of projective geometry! The book gives a simpler example that everyone was experience with, that being a shadow.
As you may know projective geometry is a mathematical science, made up of many theories that show how different projections work. In the YouTube video that I watched a man explained two of the most basic theories. The first was created in ancient Greece by a man named Pappas. This theory explains that when you draw two lines with a ruler and connect specific points you will come up with another line that if extended out would connect in a diagonal to the original two lines in addition if you do the same thing and the original lines were parallel another set of parallel lines will emerge that is telling you that the first two lines were parallel, interesting. The man goes on to discuss who this works with quadrangles that will project quadrilaterals. The second theory stated is the more modern theory of projective geometry and was created by a 17th century man from France known as Desargues.
These theories have proved to be immensely useful in our 21st century world, allowing new computer technology to develop in really cool ways. Scientists and compute technology people love the theories because they allow them to create computer images that were never thought possible. These images are fun to look at (if you are interested click on the 2nd web link below. Basically the image is colorful sphere that seems to have a fascinating shadow that moves, almost as if the sun had been projected on it all day and then recorded. The piece of art, as I would call it is entitled a “Riemann Sphere.” Basically projective geometry can be used in these computer programs (such as Java applets) to see mathematics and how it works in action, which in my opinion is a really great learning tool.
After learning about the fact that mathematicians create art using this stuff I stumbled upon a whole gallery it. Only this art was not all made on a computer, much of the internet gallery was filled with stain glass art, mathematical spirals, and conformal maps. All of the images and sculptures include really interesting names. Most of the pieces also showed to formula in a step by step fashion (written and drawn) of how the piece was created! All of this easily relates to the chapter that we read this week about space perception. The theories that make up projective geometry are one of the many ways that our brain is helping us create and understand space so that we can survive in the environment around us.
Web links
http://www.youtube.com/watch?v=fX7IOxuIjKY
http://pygeo.sourceforge.net/links.html
http://virtualmathmuseum.org/gallery4.html
Terms: projective, geometry, elmo, Pappas, parallel, diagonal, quadrilateral, quadrangle, Desargues, Riemann Sphere, spirals, space perception, and conformal maps.
Good application of how science informs technology and how we are able to interface with it.
I chose to further research random dot stereograms. I decided to research this because I have a hard time seeing the images that the stereograms are supposed to portray. I wanted to learn more about how they were made and why they were made.
A Hungarian radar engineer named Bela Julesz came along and thought that stereopsis might be able to be used to discover objects in our view. He didn't think everything was as straight forward as we all thought things were. He theorized that the random dot stereograms were important to find things that were camouflaged in our environment.
Random dot stereograms help us understand the different ways our eyes see the world, which we call binocular vision. The random dot stereograms are pairs of images set side by side several times in a given area. When one looks at the stereogram, one must look at it as though they are looking past the object. Then a 3D image will appear. This is the hard part for me, I cannot ever really see the image! Bummer. It is said that you cannot see the images using monocular depth cues, you have to use binocular disparity alone, or what Julesz called, Cyclopean.
http://en.wikipedia.org/wiki/Random_dot_stereogram
http://www.eyecanlearn.com/random_dot_stereogram.htm
http://www.psych.utah.edu/psych3120-classroom/random.html
Terms: monocular depth cues, cyclopean, random dot stereogram, binocular disparity, binocular vision, stereopsis
Its hard for me to see what is "in" the random dot stereogram as well. I often fail to see the "sailboat" or whatever is in the image.
As an artist myself, I thought anamorphic art would be good topic for me. Both a personal topic of interest but a scientific one as well; anamorphic projection is the use of rules of linear perspective to create a two dimensional image so distorted that it looks correct only when viewed from a special angle or with a mirror that counters the distortion. Dealing with the use of pictorial depth cues and pictures, pictorial depth being a cue to distance or depth used by artists to depict three-dimensional depth in two-dimensional pictures. Not exactly an easy task to manage is keeping the needed perspective in mind while drawing it, but can be done. The style of art itself was originated by the geometry of perspective. This technique was originally done, or as far as we are aware of first used by Leonardo Da Vinci. And from there through the ages things seemed to develop from there as more artist played with perspective.
There are actually two types of this perspective technique. One is called oblique; the fact that the image must be viewed from a position that is irregular from the normal view a person would position themselves. This seems to be a good example of the picture of street art in Ch 6 as well as more street art. The second type is called catoptrics; the image has to be reflected with a distorting mirror, there are also examples of these in the art community.
In the twentieth century things began to pick up as new objects of interest became subject to anamorphic art. The stairs that always go up; the Necker Cube being another example caused this form of art to grown and now there even art kits for children to be able to make their own anamorphic art.
Examples of art work: http://media02.hongkiat.com/3d_street_art/41.jpg http://browse.deviantart.com/?qh=§ion=&q=anamorphic+drawing#/d3j60nz
http://www.illusionworks.com/mod/anamorph.htm
http://www.anamorphosis.com/
http://en.wikipedia.org/wiki/Anamorphosis
Terms: anamorphic projection, Necker Cube, pictorial cues, perspective, two and three dimensional
Pretty cool application of perception and what we can see toward how we can make art that perceived a certain way by humans.
After reading chapter 6 I became interested in the section about stereoscopes. This topic was interesting to me because the first stereoscopes were very technological for their time. Also I found it interesting on how they worked to make our eyes perceive a three dimensional picture. The stereoscopes relate to the chapter because they were discussed in the chapter. Stereoscopes also use our binocular vision and our vision cues. We need both binocular vision and visual cues to perceive depth.
Stereoscopes make stereoscopy accomplishable. Stereoscopes would be the glasses or the device that is used so the viewer can perceive stereoscopic vision (stereoscopy). In stereoscopy someone can perceive three dimensional images because it is a depth illusion. In stereoscopy there are two two dimensional images placed by one another that are slightly different. Because the images are slightly different our left and right retinas view the images different, which make it possible for someone to see one image as three dimensional. The reason we can see a three dimensional images is because this is how our retinas in each eye perceive the real world, each eye sees an image slightly different than the other.
The stereoscope was first designed by Sir Charles Wheatstone in the early 1800’s. He accomplished this by using illustrations or drawings because photography had not been invented yet. Although Wheatstone is known as the person who first developed the stereoscope later versions that were invented by Oliver Wendell Holmes were more popular. In the late 1800’s and early 1900’s many families had these devices in their homes. Although stereoscopes are not as popular as they used to be because of other technological advances, like movies, they are still a device that creates an illusion in the visual system that is one of a kind.
Also after I researched the stereoscope I found that some eye doctors and therapist use more advanced versions of the stereoscope to help patients who have disorder in binocular vision and accommodation, this is an advantage of the stereoscope and a reason they are still being used. There can be disadvantages of the stereoscope are well. In order for someone to perceive the three dimensional image the two images need to be very similar, if one image has a blotch or a scratch on it then the three dimensional image will not be perceived.
Along with the stereoscope I found free fusion to be interesting. Free fusion relates to the stereoscope because it is another way to perceive stereoscopic vision. Free fusion also uses two images, but in order for a person to perceive the depth perception or a three dimensional image is for the person to cross their eyes. When someone crosses their eyes their right retina views the left image and their left retina views the right image, this causes the person to see three images rather than two and the third image is the image where the person can perceive the three dimensional image.
Terms: stereoscopes, binocular vision, visual cues, stereoscopy, stereoscopic vision, illusion, accommodation, free fusion, depth perception, right retina, left retina
http://en.wikipedia.org/wiki/Stereoscopy
http://www.dlt.ncssm.edu/collections/toys/html/exhibit01.htm
http://www.funsci.com/fun3_en/stscp/stscp.htm
Pretty interesting devices that have been around for a long time that we still use.
The topic I found accommodation and convergence from chapter 6. Accommodation is the process of the eye changing focus; the lens gets fatter as gaze is directed towards nearer objects. Convergence means the ability of the two eyes to turn inward, often used in order to place the two images of a feature in the world on corresponding locations in the two retinal images. Convergence reduces the disparity of the feature to zero. Accommodation acts like a reflex but it can also be controlled consciously. According to wikipedia, the eye can change focus from 7 cm to infinity in a matter of 350 milliseconds. The cornea provides two thirds of the refractive power and the lens only provide one thirds. Our eye has the ability to change the curvature of the lens, rather than the cornea. However, the curvature of the cornea cannot be changed. I was so interested in this topic due to my cousin has a convergence, so she has the capability of moving one eye while keeping one eye completely still. I found on Wikipedia a clip of a man who has a convergence. A divergence is opposite of convergence, that is when the eye requires rotation outward.
Another subject I was interested in was motion parallax. That is an important depth cue that is based on head movement. The geometric information obtained from an eye in two different positions at two different times is similar to the information from two eyes in different positions in the head at the same time. It provides relative metrical information about how far away objects are. A very cool example of this is a type of art work that is done that looks like two different art pieces depending on where you stand and look at it, this is called anamorphic art. In anamorphic art, linear perspective are pushed to an extreme in which the projection of three dimensions.
Terms: Convergence, accommodation, retina, refractive power, lens, cornea, curvature, divergence, motion parallax, geometric information, anamorphic art.
http://library.thinkquest.org/28030/physio/accom.htm
http://en.wikipedia.org/wiki/Accommodation_(eye)
http://en.wikipedia.org/wiki/Divergence_(eye)
http://library.thinkquest.org/28030/physio/accom.ht
Interesting. Does she report any differences from others in the way she sees the world?
The most interesting thing from the chapter I found was anamorphosis, so I decided to do further research to learn more about this interesting sensation and perception term. Anamorphic projection fits quite well within the chapter because of the topic of depth cues. As we recall we view things on this three dimensional projections, but depth cues such as these are incorporated onto a two-dimensional platform. This is what defines pictoral depth cues. Anamorphosis shows a visual image that attributes to these depth cues. In order for us to visually see the picture in a three dimension, the artist must overly expand certain points of his flat image so they look way out of proportion. Using a devise such as a mirror can help to reconstruct the image as its thought to be perceived. I started to take an interest of anamorphosis because of modern day artists who I would see on TV create these enormous sidewalk chalk drawings that looked unbelievably convincing it was more than a simple drawing. It is thought Da Vinci was the first to use this type of deceiving work in art. Also, one of the most prominent earlier examples of anamorphosis in seen in the painting entitled “The Ambassadors”. This can be further viewed from the text as well on page 143. In order to more vividly conceptualize how these images appear, it is beneficial to tink of them for the illusions that they are. With illusory contrours we perceive something that really isn’t there because the mind tricks us into believing it is. These pictures, or art forms, cause us to visually conceptualize something other than what we really see. The greatest illusions are those that are achieved through the principles of perspective. The Youtube video link posted below is really helpful for further showing the anamorphic projection, though the narrators voice is a little hard to understand during certain points.
http://en.wikipedia.org/wiki/Anamorphosis
http://www.youtube.com/watch?v=5D80A04qmO0
http://www.anamorphosis.com/what-is.html
Terms: pictoral depth cue, illusion, illusory contours, anamorphosis, anamorphic projection.
I like the sidewalk art that a few artists do. It's pretty interesting how the illusion falls apart from the right perspective/vantage point.
Stereoblindness is when there is an inability to perceive depth. Stereoblindness occurs because the retina is unable to use stereopsis. Stereopsis is when binocular disparity cues are used to determine depth. Binocular disparity is when the differences between the two retinal images combine to form a perception of depth. The retina can no longer compare the two images captured by the two separate retinas, resulting in the loss of depth perception. Similarly, those with monocular vision (one eye) also experience difficulties with stereopsis. However, stereoblindness is typically diagnosed to patients who have two, functioning eyes that are unable to use binocular disparity.
Before the revolution of 3-D media, many of those with stereoblindness would not have realized that they had a problem. Those who are stereoblind adapt to their circumstances because it most cases, it develops when the person is young. Stereoblindness often stems from childhood visual disorders such as strabismus, or the “lazy eye”. This is when the two eyes are misaligned, which has a clear connection to the difficulties with binocular disparity. There are also several tests and exercises to strengthen the connection between the retinal images, and with practice, depth perception can be improved.
A recent study by Livingston et al. sought to test if difficulties with stereopsis affected ones artistic abilities. They hypothesized that artists typically close one eye and chose to rely on monocular depth cues; such as occlusion, perspective, and shading. They then proposed that have stereoblindness could be beneficial to those relying on these cues in order to help represent a 3 dimensional world on a 2 dimensional space. The study found that on average, artists have poorer stereopsis than others. More studies are needed to confirm more details, but I found this to be an interesting point.
I chose to write about stereoblindness because I found it interesting how some people cannot see in 3-D. Personally, I strongly dislike 3D media because it gives me a headache, so when I came across this in the book I was curious to see if I could find a reason for my 3D uneasiness. Though I did not find any information that I could relate to my own “condition”, I was still fascinated with how easily stereoblindness can occur. Basically, if the eyes are misaligned at the right angle, then depth perception can be affected. It’s amazing to me how sensitive our visual system is, which is why I found this topic appropriate to write about this week.
Terms: stereoblindness, stereopsis, monocular depth cues, occlusion, perspective, shading, strabismus, binocular disparity.
http://en.wikipedia.org/wiki/Stereoblindness
http://www.wellesley.edu/Neuroscience/Faculty_page/Conway/science/my_papers/LivingstoneLaferSousaConway2011.pdf
http://www.settheory.com/stereo_blindness_test.html
I get the same experience with 3D movies. I think the right distance and angle from the screen is absolutely necessary and any movement will disrupt your experience and create headache issues as well (I think, thats just my guess).
For my blog post this week, I chose the topic of the Moon illusion. The Moon illusion is that strange phenomenon (you've probably seen in pictures if not in person) where the Moon appears to be larger when viewed near the horizon line than it does higher in the sky.
The first known recorded sighting of this strange occurrence was made by Aristotle in the year 4 B.C. In the 2,000-plus years that have passed, it has always been a topic of relatively heated debate. Though the phenomenon may not be fully explained, there are a few things we can agree upon. First of all, the Moon does NOT actually change its physical size throughout the course of each day. Another popular hypothesis, first proposed by the Greek astronomer Ptolemy in the second century, is that the illusion can be attributed to a refractory effect caused by moisture in the Earth's atmosphere. Yes, this phenomenon does occur for both the Sun and Moon just after rising above or setting below the horizon line. However, this distortion only lasts a few minutes and does not account for the perceived enlargement of the Moon when it is slightly higher in the sky. In reality, if there is any difference at all in the size of the Moon when it is near the horizon line, it is more likely to be SMALLER, since at the point in time it is approximately an additional 4,000 miles (one Earth radius) away than it is at the zenith, or highest point, in the sky!
Nevertheless, one thing can absolutely be said for certain in this debate - the effect is an optical illusion and not an environmental phenomenon! This can be proven very simply by "measuring" the relative size of the Moon in different positions against an object held at arm's length or through a cardboard tube. The Moon illusion will continue to persist near the horizon line UNTIL you measure it in this fashion. At this point you will realize that the Moon is actually seen to be the same size at all times.
Another popular theory over the centuries is Cleomedes' apparent distance theory - that since objects near the horizon are normally far away, we naturally presume that the Moon gets further away as it nears the horizon. The reason is appears larger is due to the fact that we observe a Moon of constant size as it "should" be getting further away, so our perceptual system counteracts this by perceiving a Moon that is larger.
On the other hand, 13th-century British friar Roger Bacon asserted that the phenomenon is caused by the presence of smaller intervening objects in the sight line of the Moon at horizon (later termed the "relative size theory"). This line of logic says that the Moon seems small when it's higher because it is viewed in contrast to the vastness of the entire sky, but when it is nearer to the ground, it seems bigger because it can be compared to several objects that are much smaller.
In general, some combination or modification of these last two theories is the modern explanation that is more commonly accepted. In general, viewing an object while accommodating for a closer distance will always reduce its perceived size to some degree. Nonetheless, it is important to remember that we must put the horse before the cart in rationalizing this sort of phenomenon - variations in the objects of angles do determine our perception of depth; however, as Kaufman and Kaufman astutely point out, attributing perceptual size illusions as an indicator of perceived distance does not jive because that is essentially crediting a perception as the cause of another perception.
http://www.philosophy.leeds.ac.uk/GMR/articles/ptolemy.html
en.wikipedia.org/wiki/Moon_illusion
http://www.pnas.org/content/97/1/500.full.pdf+html
Terms: Moon illusion, refraction, zenith, apparent distance theory, relative size theory
Good description and explanation for something we see all the time and don't necessarily know the reason behind it.
Binocular cues where what I chose to do further research on. I am amazed at the things that we are able to do because of the things that we learn from the information that both eyes receive.
The main binocular cue that I want to focus on is motion parallax. It is a depth cue that is based on head movement. Motion parallax is a motion cue not a pictorial depth cue. Since it is not a pictorial cue it is not based on how the three dimensional world that we see falls on our retina which is two dimensional. What sets it apart from those cues is that things are moving so they can not be produce on the retina as a static image.
The examples in the book and also in my research continued to stress that objects closer to us always appear to move faster than those further away. I found that to be an interesting thing and something that I had never thought about. A study was done on to see what effects alcohol would have on an individual’s motion parallax while driving. The results were staggering; they stated that at a blood alcohol lever of .1 individuals skill with motion parallax appeared to be about 4.5 times worse than normal. Since motion parallax plays such a vital role in the depth perception it should be of no surprise why drunk drivers have so many accidents
Depth perception is also something that binocular cues are used for. The reason that binocular cues play such a big role in this is because the eyes do not both see the image at the exact same angle. When the two different angles are brought together they basically triangulate the positioning of whatever is being viewed. The size of objects on the retinas also speak volumes about how near or far an object is. Binocular cues play a very large role in how we interact with the world around us. Whether things are still or moving the use of both eyes to get a feel for our surroundings is a great necessity.
Key terms: pictorial depth cues, motion parallax, binocular cues, retina
http://www.ndsu.edu/ndsu/news/magazine/vol05_issue02/in_depth.shtml
http://en.wikipedia.org/wiki/Parallax
http://www.universetoday.com/78860/motion-parallax/
http://en.wikipedia.org/wiki/Depth_perception#Binocular_cues
Good point. Drunk driving = bad news.
The topic I chose was 3D technology. This is where images from TVs with 3D technology are distorted just enough so when the brain puts the images together from both eyes it looks like our natural binocular vision. In other words, the screen displays two images that are slightly different from one another in terms of looking at an object from a lightly different angle. Then one image is blocked out by the glasses that have to be worn so that each eye gets a different image. This is how binocular vision usually works and the brain automatically puts the image together to create depth perception. I think this topic is interesting mostly because technology has taken big strides in the past decade or so. I remember my first 3D movie; I think I was six at the time because I don’t think my sister was born yet. Anyway, it was at Warner Brother Studio and it was a theater built for 3D movies. I remember thinking it was really cool. Years later, the theaters at Crossroads (in Waterloo) and College Square (in Cedar Falls) started showing 3D movies. Except when I went to those, I almost hated it. I have such a hard time focusing on the entire image from the screen because of it being 3D. Games/gaming in 3D is a completely different story.
I first found out about gaming in 3D through my Dad who tries to learn about the most recent gaming technology when he has free time. Today, the 3D gaming choses include having to pick between active and passive 3D glasses. Passive glasses work by being polarized to block out a different image in each eye. When glasses are polarized they actually have microscopic lines going across the lenses. These lines will go veridical on one eye and horizontally in the other. The way to check to see if lenses are polarized is to hold them up to each other and turn one. When the lines match up they will completely block visibility through them. With 3D TVs they will block one image while the other lens blocks the other image. Typically these are cheaper than active glasses, lighter, and don’t need to be charged or synced with the TV. Active glasses are electronically polarized to allow in the desired image given off by the screen and automatically change with the screen by refreshing how much they are polarized. The video on YouTube I found does a great job of demonstrating this. Even though active glasses come with a few disadvantages, they hold one advantage that passive glasses could never compete with; active glasses obliterate split screen gaming!
Now two people can play a two player game on the same screen and each person sees their own full screen. The active glasses can allow for each person to play their own person in a game and not be limited to half a screen. If you ever get some free time at BestBuy check it out because it’s fun to play with. Even though I am not a huge gamer and I don’t usually play a lot of two player games, being confined to a tiny little screen always bugged me. Especially when it was a game I hadn’t ever played before and I didn’t know what screen was mine to be watching. I got a lot of slow starts in racing games that way.
http://www.youtube.com/watch?v=_k7Vc10YsDk (YouTube video demonstration)
http://www.3dtvguide.org/3d-glasses.html
http://www.pcworld.com/article/225218/active_3d_vs_passive_3d.html
Terms: 3D technology, binocular vision, depth perception, polarized lenses, passive 3D glasses and active 3D glasses.
Interesting. 3D movies and games seem like a scam to to me. We already can perceive 3D.
Motion Parallax defines difference in distance and motion, and is associated with depth perception. As an example, this would be you passing by a street sign while in your car and the sign looks a lot bigger than it does when it is far away. This is not only used in psychology, but also in art education where they study the movements of movie clips.
Parallax includes optical instruments (binoculars, microscopes, and twin-lens reflex cameras which view objects from slightly different angles). Stereopsis, is where us humans and some animals have overlapping eye images that would interfere with our image if we didn't see images as one.
Object remains stationary on the retina, objects farther in depth appear to move in the direction of observer translation. Objects nearer in depth appear to move in the direction opposite observer translation.
http://www.jstor.org/stable/1319874
http://psychology.wikia.com/wiki/Motion_parallax
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2276660/
http://psych.hanover.edu/krantz/motionparallax/motionparallax.html Another good site about motion parallax. Things closer to you seem to go by faster than those further away. Interesting stuff.
After reading chapter 6, I found numerous topics that sparked my interest. There was a lot of talk about binocular and monocular vision throughout the chapter which raised a question in my mind. My father lost vision in one of his eyes when he was a teenager and has only had vision in his right eye for most of his life. I’ve always wondered what it was like for him to see just through one eye constantly. The strange thing about his monocular vision is that he usually sees things much quicker and faster than I can. I never quite understood if this was just from adaptation or was his monocular vision just better than my binocular vision. I decided to find some more information out about each type of vision to come to a conclusion on the matter.
As we all know, monocular vision is with one eye and binocular vision is with two eyes. While reading through some websites I discovered that most of them agreed on 4 major advantages of having binocular vision. The first was simple; having two eyes is advantageous in case one of the eyes is damaged. The second reason was the field of view that two eyes have over one. When we have two eyes we can see 200 degrees, while with one eye we only have the ability to see 120 degrees around us. A third reason was binocular summation. Binocular summation, according to the book, is the combination of signals from each eye in ways that make performance on many tasks better with both eyes than with either eye alone. What that basically stated was that it’s harder to detect a stimulus with one eye than with two. The book had a good example; having two eyes is like having two people look for an object. The forth reason for binocular vision was stereopsis. Stereopsis is the ability to take two images from each eye (binocular disparity) and combine them. The brain then has the ability to determine depth through each of the images that both eyes are observing. This is very useful in our depth perception. Examples of stereopsis are things that affect our fine manipulative skills and spatial discriminations like threading a needle, judging the space between one’s car and other cars on a crowded highway, and many sports.
People with monocular vision have troubles with Peripheral vision and depth perception. Monocular vision people have a 20 percent lose in their peripheral vision. While not much of a loss, it does create a large blind spot on the side where you don’t have vision in the eye. This is adjusted by walking by a wall or by walking with a partner. Monocular Depth Perception makes judging distances much harder than that of someone with binocular vision. This makes everyday situations much harder. Simple things like pouring a drink, using silverware to pick up food, walking down stairs, etc become increasingly difficult to judge the distance and depth of each task.
My personal opinion on monocular vision is that just like any other thing in life, people adapt. I can honestly say that my father has no troubles with any task that is presented in front of him. In most cases he sees things and does things at a much higher level than I do. So even though scientifically I have every advantage in vision with binocular eyes, it doesn’t seem to be that big of an advantage compared to someone who has adapted to monocular vision.
Terms: binocular, monocular, stereopsis, depth perception, peripheral vision, binocular summation, binocular disparity.
http://artificialeyes.net/adjusting-to-eye-loss-mind-map/adapting-to-monocular-vision/
http://en.wikipedia.org/wiki/Monocular_vision
http://en.wikipedia.org/wiki/Binocular_vision#Field_of_view_and_eye_movements
http://www.svs-greensboro.com/why2eyes.php
Good points. People definitely adapt to their environment and to losing some type of perceptual or sensory ability. Have you asked your Dad how he perceives some of these things/illusions you've been learning about? Could be cool to find out how he perceives them.
I chose to do my topical blog on anamorphic art because I think that it is neat how they can make things look three dimensional when they are actually not using different techniques. It fits into the chapter because the chapter talks about different ways of viewing things in a three dimensional way, and how things can look three dimensional and actually be on a flat surface. There are two forms of anamorphic art, mirror and perspectival anamorphisis. There are many examples of both types of art dating back to 1485 with Leonardo da Vinci’s painting Leonardo’s Eye.
This is common in recent day art as well. Many artists play with rod shaped mirrors placing them on a surface and then drawing around the rod shaped mirror. They must draw the image in a distorted way to make it look right on the mirror. It then gives the illusion that the mirror is projecting the image on the paper instead of the other way around.
When doing these drawings without mirrors, perpectival anamorphisis, an artist starts with a gridded paper and another paper with the same number of trapezoids. They must draw the picture on the square girl then cope the contents of each square onto the corresponding trapezoid of the other grid. They stretch the lines so that it all fits together. When looking at the final product (the one with the trapezoids) it looks distorted, but when it is looked at at a certain angle it appears undistorted.
In the 20th century artists began attempting to draw “impossible objects” an example being the “neckter cube.” This is that 3D square on a 2D surface that everyone learns to draw in art class. Artists started to begin to experiment with drawing things in perspective, and in a way that demonstrates depth and 3 dimensions on a 2 dimensional surface. Other examples of things that were beginning to be experimented with are stairs. A really interesting example of “impossible objects” anamorphic art is the penrose triangle. It is a field goal looking sculpture that when looked at at the right angle appear to be a perfect triangle.
This form of art uses many tricks of the eye to give its illusion. Pictorial depth cues are a big deal in this form of art. This gives viewer a cue to depth and allows for things to look three dimensional in a 2 dimensional world. In most cases nonmetrical depth cues are used. This gives us the general ordering of the objects. So it lets us know what is in front of certain items and also how far behind the item is, and it gives us information about how big or small an item is in comparison to other things. Linear perspective is something that is used greatly in this form of art. This basically says that lines that are parallel in a 3 dimensional world will appear to converge in a 2 dimensional world. This is useful when drawing anything, but especially important when attempting to make thing look 3 dimensional on a 2D surface. So the necter cube and any of the drawings on the sidewalk in the link below would be applicable to the linear perspective. They all use some vanishing point to make the image remain in perspective in the drawing. I think these forms of art are very mind blowing and it is interesting to understand how they work and why we are able to see them as three dimensional on a 2 dimensional surface. I mean some of them you can’t even see them as flat. They only look 3 dimensional they are that good. I think that is really cool.
Terms: anamorphic art, mirror anamorphisis, perspectival anamorphisis, nonmetrical depth cues, pictoral depth cues, linear perspective, vanishing point,
http://en.wikipedia.org/wiki/Anamorphosis
http://en.wikipedia.org/wiki/Penrose_triangle
http://www.princetonol.com/groups/iad/lessons/middle/grid-drawings.htm
http://www.instructables.com/id/How-to-do-3D-Anamorphic-Artwork-and-Sidewalk-Stre/
I think the cool thing is that these sidewalk art pieces only work from the right perspective. When you look at it from the wrong direction it doesn't look 3D. Indicates the intricacy necessary to make them look 3D and real.
After reading this chapter I wanted to focus on the intattentional blindness topic. I began to think about this topic after I read more about it, and wondered how many objects I have failed to perceived that was in my full view in everyday life. I have truly tried to perceive more in my environment after learning about inattentional blindness.
1. The video I found on inattentional blindness, it shows how everyone focuses on one thing at a time. The observation is that our brain has an amazing amount of information that is kept, and it is hard to focus on everything in our full view. The experiment was having a team of basketball team throw a basketball around and count how many times the yellow shirt players tossed the ball. However, the participants did not notice the gorilla walking in between the players while they were tossing the ball. They were asked if they saw anything strange, and some people did and others didn’t due to inattentional blindness, the brain did not register the gorilla suit guy. This is a great example that our brain can focus on one thing and concentrate so hard, and completely ignore something so obvious and bizarre that we SHOULD have noticed. I also did this experiment in my Applied Psychology class, and I did not notice the gorilla at first, until after we were told about it. I found this video to demonstrate the brains attention and focus and lack of full focus at times.
http://www.youtube.com/watch?v=y6qgoM89ekM
2. A full research report that was published by a student of the University of Iowa wrote about inattentional blindness, and how everyone can experience no memory of seeing things that were in there point of view. A great example of this would be if a person is driving for a while, and was asked about certain objects or landmarks during their drive, many people would not have the memory of seeing those objects, even though they had to have noticed or processed the images around their environment. Inattentional blindness is a kind of ILLUSION to many individuals once they have no recollection of visual scenes around them. Our brain is selective to objects and can not capture everything and process it all together, the brain already is focusing so much on other things. The failure of perception is interesting because people think they do not “miss” anything that is in their view, but that usually isn’t the case. This report explains how our experiences can be distraction and unconscious experience.
http://www2.psychology.uiowa.edu/labs/iapl/iAPL_people/cathleen_moore/pdfs/moore_in_press_OCC.pdf
3. The third article I found explains how the brain can “ignore” a whole environment around us. The brain has a task to focus and respond to high load task, but it reduces but the level of precision of neural responses to anything that is not part of that ONE task we are focused on. Our brain simply ignores the outside objects, due to using energy and signals perceiving a task in our visual region. Neurons respond weakly to “noise” in our environment because our neurons are responding to one particular task at a time. I found the neurological perspective to be interesting, because the brain does this without “us” telling it to focus on only one thing. The brain is so complex, that people do not know they are subconsciously ignoring whole objects around them.
http://www.ucl.ac.uk/news/news-articles/1207/17072012-Inattention-blindness-due-to-brain-load-Lavie
vocab: neurons, illusion, inattentional blindness,visual scenes, visual environment, selective attention
This week, I chose to talk about illusions. Illusions are shown in the book as drawings that mess with your eyes and make you think you are seeing things that you truly aren't. Illusions make me think of magic and that is why I decided to look into them.
Oh my goodness. I loved this website! It gave more examples of optical illusions due to vision than I ever knew existed. Michael Bach described illusions as limitations in the eyes. I think that is a great way of describing it because it is basically your eyes failing to understand what is truly going on.
http://www.michaelbach.de/ot/
I researched illusions on the American Optometric Association website and I found that the time when your eyes naturally see illusions is at night. Yes, illusions on the internet can be all fun and games but how does that relate to my eyes everyday? This website explained that because of the different lighting at night, your mind will see different movements and even different images.
http://www.aoa.org/optometrists/tools-and-resources/clinical-care-publications/aviation-vision/the-eye-and-night-vision?sso=y
So lastly, I went to illusions.org to see how many illusions I could debunk and how many just tricked me! It is so awesome how your eyes can start seeing things that aren't really there once you stare at something for too long. I thought it was crazy how sometimes I couldn't see anything for forever and then the second I read the caption, my mind finds it and can't get the illusion out of my head! The ones that I loved the most was when you stare at a negative image for 30 seconds and then look at a white piece of paper and you see a real picture! Crazy! How does my mind know what the real image looks like? Eyes are crazy.
http://www.illusions.org/