What I would like you to do is to find a topic from chapter 7 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.
By now you all should be skilled at synthesizing the topical material you have obtained from the various web sites you visited. If you need a refresher please let me know.
Thanks,
I found the reflexive eye movement particularly interesting. The reflexive eye movement is a movement of the eye that is automatic and involuntary.
Although we call them “voluntary,” you generally do not consciously think about making saccades, pursuit, and vergence eye movements. Certain portions of your brain are continuously firing away in the background to plan these eye movements, but all you are concerned with is the visual information received once the eyes get to their final destinations. The portion of the brain that is continuously firing away is particularly the superior colliculus.
However, even if you try to keep your eyes perfectly still, your gaze continues to jitter a little. These miniscule tremors of the eye muscles are called involuntary eye movements, and you normally do not even notice them.
What possible function could these eye tremors serve? Some fascinating experiments have revealed that when an image is kept perfectly stationary on the retina. This is actually counteracting the effect of the normal involuntary eye movements. The image actually disappears after a few seconds! It is not known exactly why this happens, but the result implies that constant retinal motion is necessary for the visual system to function properly.
http://www.mitpressjournals.org/doi/abs/10.1162/089892904322984599
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5333504&abstractAccess=no&userType=inst
www.medlectures.com/Neuro%20Lectures/eye_movements.ppt
http://fmri.nl/index.php?option=com_content&task=view&id=30&Itemid=279
Akinetopsia is a rare neuropsychological disorder in which the affected individual has no perception of motion. Akinetopsia is casue by disruptions to cortical area MT. I found couple interesting videos that introduce people who suffer of akinetopsia. They talk how can life with it and what problem does it causes. The women from the video struggle to go across the street because she cannot see how close the car is. She can only recognize it by hearing.
Another video introduce visual effects of akinetopsia.For example, walking, driving that was impossible because with this disorder it makes you confused by multiple snapshots of cars, streets, and signs.One patient, LM, described pouring a cup of tea or coffee difficult "because the fluid appeared to be frozen, like a glacier".She did not know when to stop pouring, because she could not perceive the movement of the fluid rising.
Besides simple perception, akinetopsia also disturbs visuomotor tasks, such as reaching for objects and catching objects.
After introducing couple examples of people suffering from akinetopsia, we should know what exactly happen in our brain.
Thus, he neurons of the middle temporal cortex respond to moving stimuli and hence the middle temporal cortex is the motion-processing area of the cerebral cortex. In the case of LM, the brain lesion was bilateral and symmetrical, and at the same time small enough not to affect other visual functions.
http://www.youtube.com/watch?v=B47Js1MtT4w
http://www.youtube.com/watch?v=SVdiMLrr77Q&feature=related
http://www.medscape.com/viewarticle/410860_6
I decided to do more research on the topic of apparent motion. Apparent motion is the perception of movement of two stationary objects. This concept is based off an illusion discovered by Max Wertheimer during the Gestalt Psychology Revolution in 1912 called the phi phenomenon. Wertheimer discovered one day that two lights that flashed quickly and right next together looked like they were moving. What’s important in creating this illusion is that the lights must be flashed at a certain speed. If the speed is too fast, it just looks like two lights flashed. If it’s too slow, it looks like one light flashes followed by another flashing light. The speed must be correct in order to see a succession.
There are different kinds of movement like this, such as beta movement and illusory movement. Beta movement is the perception of movement between still images. Illusory movement is the perception of movement on one static image. Although all three are types of apparent motion, beta movement and the phi phenomenon are not the same thing. The phi phenomenon is the illusion of movement by lights in a sequences and beta movement is the illusion of movement by lights from stationary objects.
An example of apparent motion that helps to understand the concept of apparent motion is a flip book. When looking at a flip book, you perceive motion but know that there’s just a different image on each page. The flip of each page can be compared to our eyes because our eyes are constantly moving, at a rate of about 60 times a second. Because our eyes don’t send information to our brain while in motion, our eyes are like cameras. They take still images and send them to the brain and it’s in the brain that these images are put together to form motion. So, apparent motion is very similar to real motion because our eyes are always capturing images, whether it’s truly moving or not, and sending that information to the brain to piece them together. I think this is pretty amazing how fast our visual system works with the brain to put together our world.
Terms: apparent motion, perception, illusion, motion, images, visual system
http://www.youtube.com/watch?v=_ulQ_vaBM0Q
http://coglab.wadsworth.com/experiments/ApparentMotion.shtml
http://en.wikipedia.org/wiki/Phi_phenomenon
I chose to further my interest on akinetopsia which is a rare neuropsychological disorder in which the affected individual has no perception of motion. Akinetopsia appears to be caused by disruptions to cortical area MT. in other cases; akinetopsia is brought on by direct trauma to area MT due to stroke or elective brain surgery (i.e., surgery to alleviate epileptic seizures. In addition, Akinetopsia is an acquired defect of visual motion perception caused by acquired cerebral lesions. As motion vision serves many purposes. A variety of defects can result including defective smooth pursuit eye movements, reaching for moving objects, and identification of objects defined by movement cues (structure-from-motion or kinetic depth). Cerebral akinetopsia is a syndrome in which a patient loses specifically the ability to perceive visual motion following cortical lesions outside the striate cortex. Furthermore, the middle temporal (MT) and mesial superior temporal (MST) areas occupy the floor and walls of the superior temporal sulcus in primatesand contain neurons sensitive to direction and velocity of visual targets. Lesions of MT (a.k.a. V5) produce a relatively selective deficit for motion perception in the contralateral visual hemifield, which recovers within a few weeks, depending upon the extent of the lesion and white matter involvement. Human motion processing deficits have been attributed to lesions in a human homolog of the area MT complex, thought to be located around the junction between the temporal, parietal, and occipital lobes, as suggested in the landmark case of "motion blind" patient L.M. Unilateral lesions of lateral occipito-temporal cortex or inferior parietal lobule may cause hemiakinetopsia, producing impairments of motion processing in the contralateral visual hemifields. Unilateral lesions can also impair motion perception in the central visual field. The last video I found shows the visual effects of how a person with this disorder sees things.
http://www.youtube.com/watch?v=B47Js1MtT4w
http://www.medscape.com/viewarticle/410860_6
http://brain.oxfordjournals.org/content/114/2/811.short
http://www.youtube.com/watch?v=QW53fRQv3Zo&feature=related
I also decided to further my knowledge on the topic of Akinetopsia. Akinetopsia is a rare neuropsychological disorder in which the affected individual has no perception of motion. Commonly, those who have akinetopsia will view objects changes position, and are fully aware of the location shifts, but they have no experience of the perception of motion. Akinetopsia can cause everyday tasks to be more difficult. It is almost impossible to cross the street, to pour juice, or to enjoy a movie. Not to mention the trouble it would cause in calculating the time to collision (the time required for a moving object to hit you in the head TTC=distance/rate)
In order to learn more about Akinetopsia I did a quick youtube search. The first video I found explained the first known case of Akinetopsia. The patient, LM, had a stroke that damaged both sides of her brain at the lateral boarder between the temporal and occipital lobes. She was found normal in all other aspects besides her motion vision. She had complaints of difficulties following a dialogue because she had problems following the mouth and facial expressions of the speaker. LM's stroke caused damage to V5 which is the same area where motion is constructed in the brain. The case of LM has taught us a lot of what we know about Akinetopsia today.
Brain lesions are a rare cause of akinetopsia. This is because they are normally not small enough to only damage the motion perceiving section of the brain, and will damage other visual areas such as color vision or spatial vision. As of now, traumatic brain injuries seem to be the most common cause of akinetopsia. One interesting thing that I discovered in my research was that sometimes Alzheimer's patients may experience akinetopsia. This contributes to their feelings of disorientation. However this has been the case for some cases, more research needs to be done of the topic.
As previously mentioned, V5 plays a big role in Akinetopsia. V5, or the MT(middle temporal), is the processing center in our brain for motion. All of the neurons in V5 are motion selective, and most are directionally selective. Also, studies have found that lesions to V5 cause motion blindness. V1 was once thought to be another important area in motion blindness. However studies have found that lesions to V1 will not stop motion completely but may limit the perception somewhat. As long as V5 is still intact the patient will still have motion perception.
Unfortunately there is currently no cure for Akinetopsia. Recognizing the disorder requires completion of a visual stimuli test. The patient will be presented with a video of one dot that will appear to change from location a to location b. The two different locations are approximately one inch apart. The dot will move at varying speeds. If a patient has normal motion perception, they will only see one dot at a time. However, if a patient has Akinetopsia, the visual stimuli will appear as two separate dots that keep flashing.
http://www.medscape.com/viewarticle/410860_6
http://www.youtube.com/watch?v=B47Js1MtT4w
http://www.youtube.com/watch?v=tYFhDzQ1rYU&feature=related
http://en.wikipedia.org/wiki/Akinetopsia
I also found akinetopsia to be very interesting. Akinetopsia is a rare neuropsychological disorder in which the affected individual has no perception of motion. I thought of it like a movie where they see the frames happening and life progressing however they do not perceive life like we would a movie where it is a constant flowing film. People with akinetopsia may have trouble crossing the street because they cannot perceive where the cars are actually at and how fast they are going. They also have problems pouring a beverage into a glass because they cannot perceive the liquid rising in the glass. This would make every day living quite difficult on your own.
L.M. is a patient with Akinetopsia that has been researched for many years. She had a stoke that caused damage to the intersect of her occipital lobe, parietal lobe, and her temporal lobe. Because of this stroke, she had problems pouring drinks, being in crowds of people and watching movies. It was hard for her to watch the dialog because she couldn't make out the actors mouth and body movements.
Akinetopsia can be caused by sideeffects of certain medications, brain surgeries, and stokes. In some cases of alzheimers patients have had akinetopsia or has had their perception intensified. Some causes of akinetopsia can be fixed and others remain more permanent.
Sources:
http://www.youtube.com/watch?v=B47Js1MtT4w
http://www.medscape.com/viewarticle/410860_6
http://en.wikipedia.org/wiki/Akinetopsia
One topic that I found interesting was optic flow. Optic flow is the pattern of apparent motion of objects, surfaces, and edges in a visual scene caused by the relative motion between observer and the scene. Optic flow includes a number of techniques including, motion detection, object segmentation, time to collision and focus of expansion calculations, and motion compensated encoding. I was amazed at the fact that there is a way to estimate optical flow. This method was created by Barron, Fleet, and Beauchemin; they built their method on Taylor series approximations of the image signal, resulting in an equation for estimating optical flow. However one problem with this equation is two variables that cannot always be accounted for, this problem is related to the aperture problem. The aperture problem implies that motion sensitive neurons in the visual primary cortex will always respond to a contour that crosses their receptive field, independently of its true length and orientation, as long as its direction is consistent with the preferred direction of the neuron. This problem arises as a consequence of the ambiguity of one dimensional motion. Optic flow is also very useful in subjects outside of psychology. One area that optic flow is used in is the compression of video files; video files are compressed to help cut down on the amount of space that they take up. With the help of optic flow they know what things they need to keep in the image to preserve what we see, but they can get rid of things that are not very useful to save space. Another area that optic flow has been useful is robotics; optic flow has been used in robotics to help with object detection and tracking, movement detection, and robot navigation. These areas will be key if scientists want to be able to create robots that can see and perceive objects.
Sources
http://en.wikipedia.org/wiki/Optical_flow
http://www.psico.univ.trieste.it/labs/perclab/integration/english_version/aperture.php3
http://pages.slc.edu/~ebj/sight_mind/motion/Nakayama/aperture_problem.html
Some examples
http://www.youtube.com/watch?v=ckVQrwYIjAs
http://upload.wikimedia.org/wikipedia/en/1/10/Optical_flow_example_v2.png
I chose to look more into the topic of eye movements. One term that goes along with this is smooth pursuit. This is the type of eye movement where the eyes move smoothly to follow a moving object.
Along with this topic is the physiology and types of eye movements. In the figure in the book, it shows that there are 6 muscles attached to on eye which are arranged in pairs. If a cell in the midbrain, or superior colliculus, is stimulated, the eyes will move by a certain amount in a specific direction. Every time hat certain cell is stimulated, it will have the same eye movement. The other surrounding cells, if stimulated, will make different eye movements. The superior colliculus can also get input from ganglion cells in the retina which helps plan eye movements. The six muscles are called superior and inferior oblique, superior and inferior rectus, and medial and lateral rectus. These muscles help to look at the same object at one time. They also allow our eyes to keep moving.
This leads us to they different types of eye movements. Vergence is a type of eye movement where the two eyes move opposite directions. An example is when a person goes crosseyed, and both eyes go towards the nose. Saccade, however, is a rapid movement of the eyes that changes fixation form one object or location to another. When we view something, our eyes tend to fixate on the interesting parts of the picture or image. Reflexive eye movements, however, are movements in the eye that are automatic and involuntary. For example, when we are focusing on an object and move our head, the eye will correct itself and move to keep focusing on that object. These are also known as vestibular eye movements and are run through the vestibulo-ocular reflex.
I found an interesting aspect of this on google about lies and eye movement. While they didn't come out and say that if a person looked around if they were lying, they did bring up some interesting points. If a person looks up and to the left, it indicated that they are visually constructing an image. For example, if a person would be asked to picture a green elephant, they would look up and to the left on average to create this image. However, if someone was asked what the color of their first house was, this called a visually remembered image, which would cause a person to look up and to the right. Auditory construction, or being asked to create a pitch in their head, would cause a person to look to the left. Auditory remembered, however, is when a person is trying to remember a certain pitch or sound. For example, this is when a person is asked to remember the sound of their mother's voice. This would cause a person to look to the right. Looking down and to the left would indicate feeling or kinesthetic. This would be a taste, feeling, or smell. For example, this would take place if a person was asked to remember the smell of a campfire. The last one is internal dialog, when a person would be looking down and to the right. A person will look this way when they are talking to themselves. The website tied this all together by giving an example. If a child asked you for a cookie, and then you ask, "What did your mother say?" If the child looks to the left, it would imply that the child has constructed this answer, because this indicated a constructed image or sound. If he looked to the right, it would indicate that he is remembering this image or sound, so he would be telling the truth. I found this to be very interesting, though I don't know if it is completely true. As I was thinking these things to myself, I wasn't looking down and to the right much, so it's hard to tell how accurate it is. But it was an interesting idea!
http://www.youtube.com/watch?v=kEfz1fFjU78
http://ravan2006.blogfa.com/8509.aspx
http://www.blifaloo.com/info/lies_eyes.php
Akinestopsia is a very rare neuopsychological disorder where the individual has no perception of motion. As described by the individual in the book, if what he was viewing didn’t move his vision was fine, the moment something moved his vision became frozen. What’s interesting about akinestopsia is that it because it only effects the perception of motion, the background of the strobe light moving person is completely still and what normal vision would perceive.
Patients with akinetopsia struggle with day-to-day activites because as one patient put it, it was very difficult to poor herself coffee because with her visual disorder it looked like the liquid was freezing in place before it entered her cup, and she didn’t know when to stop pouring because she couldn’t see the liquid actually rising in the cup.
What individuals get akinetopsia? As stated in the book akinestopsia appears to be caused by a disruption in the cortical area M such as direct trauma to the MT area by a stroke or elective brain surgery to relieve epileptic seizures. The book also stated that the individual described in the book acquired the disorder as a side effect to his antidepressant medication and soon after his medication was discontinued he vision returned to normal. Akinetopsia has been reported in individuals with a traumatic brain injury, lesions on the posterior visual cortex and a case study has shown Alzheimer’s patients may have some degree of akinetopsia. Akinetopsia can also be induced in patients by using a transcranial magnetic stimulation (TMS) to stimulate an area visual areas for motion processing in healthy subject’s brains.
Individuals can also have hemi-akinetopsia which is when the individual has normal motion perception in one eye and can’t see motion in the other eye. One patient actually describe it as seeing normal with one eye and having a strobe light going off through the other eye. I can only imagine how awful that would be, and the headaches that would bring.
I added a video from youtube that was very informative for me and it gave me a chance to experience what akinestopsia may be like for the individuals suffering from it. Hope you guys check it out!
http://www.youtube.com/watch?v=B47Js1MtT4w
http://en.wikipedia.org/wiki/Akinetopsia
http://vectors.usc.edu/issues/4/malperception/akinetopsia.html
http://www.jstor.org.proxy.lib.uni.edu/openurl?volume=249&date=1992&spage=173&issn=09628452&issue=1325
We have studied that motion parallax is a depth cue (things closer to us move faster than things faster away). And the book states that motion parallax alone cannot really be capture in just a picture. It amazes me that motion can be capture 2D at all, however motion is captured on film, produced in animation, even in paintings all the time.
After reading the chapter on motion, the perception of motion seems to be a lot like color. To see motion or the illusion of motion, you most look at the whole not the parts. This is similar to color because color is produced by the combination of different wavelengths. Color reflecting of surfaces in the real work or producted within 2D scenes are made up of many smaller elements put together. The article “Motion Perception in Movies and Painting: Towards a New Kinetic Art” talks about how animation and movie film can be explained using Gestalt psychology theories ( that the whole is more important than the parts). Motion is creating by the changing of the scenes. The individual scenes differ. This works because the sequence of scenes move towards the events we believe are go to happen. Similar in painting motion can be captured by targeting the same expectance. We aspect the moving waterfall to be hitting the rock a certain way (based on heuristics), thus it is possible/easy to creature the illusion motion. The website “The Secret life of the Brain: Mind Illusion” by PBS explains why we are able to see motion in still photos or things like optical illusions. Our perception is affected by “misreading”; in our words our nervous system approximates color shape and dimensions. Furthermore, it shows how our perception of the world is affected by our expectation from past experiences and associations. This again points out how our mind operates in heuristic. We want to see the total scene. That is why we are able to use color and motion in paintings and on the screen. Our mind does not force on the parts but the whole it creates.
In the article “The Strange Symptoms of Blindness to Motion” talks about a person who cannot see motion at all. This means she could not see cars, or water unless it was still. This condition to me is very interesting. The article states that the patient sees movies( and life) as a set of still photos.
http://www.ctheory.net/articles.aspx?id=349
http://www.pbs.org/wnet/brain/illusions/index.html
http://www.google.com/search?client=safari&rls=en&q=he+Strange+Symptoms+of+Blindness+to+Motion&ie=UTF-8&oe=UTF-8
Motion perception is crazy. First order motion, motion of an object with well defined edges, is detected by a combination of processes that evaluate orientation of the object and direction and speed of the motion. The book describes the process of detecting motion on the retinal and ganglion level using the Reichardt model. It takes two receptive fields being monitored by two separate ganglion cells. When the first is stimulated it sends a yes signal, but the signal is delayed. If the stimulation continues and crosses the second field the second ganglion sends a yes signal as well. A third cell receives signals from both ganglion cells and if both signals are yes than the third cell sends a signal indicating it has detected motion. If the cell does not receive a signal from the second field it means the stimulation has not moved enough to stimulate a second field and motion will not be detected. If the cell stops receiving a signal from the first cell it means the first cell has adapted to the presence of the stimulation and that although the stimulation may continue to move across other fields, it is stimulating this field in the same way. This system of ganglions tied to receptive fields tied to motion detector cells daisy-chains all the way across the retina, and is not limited to the fovea by any means. In fact rods are often much more useful in detecting motion because they provide large receptive fields made up of many cells.
This illusion (http://psy2.ucsd.edu/~sanstis/Dot.html) is really interesting. It is possible because as our eyes smoothly pursue the mouse cursor, they sweep across the black line or dots making it seem as though they are moving when it really our eye that is moving. Our receptive fields are stimulated and motion is detected, but motion detection higher in the brain is controlled by neurons that are sensitive to orientation and direction. Our brain is interested in contrast or change, so when we detect a black line moving our brain quickly begins to ignore movement that is consistent with the orientation of the line. Our brain also begins to ignore movement that is parallel to the direction we are moving our eyes. The slant of the line, when you subtract the horizontal movement parallel with that of our eyes, is such that the line appears to only be moving perpendicular or upward.
On the retinal level receptors and ganglions act only to detect motion. It takes the collection of millions of neurons in the visual cortex and the middle temporal lobe, among other regions, to be able to deduce the three dimensional direction of motion. The book discusses a concept called time to collision, which refers to our processing of objects that are coming at us, and may be dangerous. Tau is a cognitive measure of an how fast an object is approaching our retina. As an object approaches it appears larger on retina taking up more space on the retinal surface. Tau is the ratio of how much retinal space an object occupies to rate at which it is expanding on the retinal space.
The book discusses biological motion. It discusses putting lights on a person in a pitch black room. When they stand still they look like a collection of lit dots but when they move we get a very definite impression of human movement. This is a link to a video demonstrating this effect with Ramachandran narrating. http://www.youtube.com/watch?v=FAAyB5jGx_4
http://psy2.ucsd.edu/~sanstis/Dot.html
http://www.youtube.com/watch?v=FAAyB5jGx_4