Please
read chapter 8.
After reading chapter 8, please respond to the following questions:
What were three things from the chapter that you found interesting? Why were they interesting to you? Which one thing did you find the least interesting? Why? What did you read in the chapter that you think will be most useful to in understanding Sensation & Perception? Finally indicate two topics or concepts that you might like more information about.
Note:
Keep in mind that there are no scheduled exams. When you make you posts
make sure they are of sufficient caliber that the could be used as
notes in a test - since the posts are what we are doing in lieu of an
exam. Be sure to use the terms and
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After reading chapter 8, I found many topics interesting to learn about, but there were a few that stuck out in my mind. The first topic I found especially interesting was visual search experiments, because these give a more accurate approximation to attention in the real world, than do many other cueing experiments, especially related to reaction time. During one of these visual search experiments, the subject searches for a target in a display full of distractor elements. The target is the goal of the visual search. As humans, we do this in the real world all the time, looking for necessary objects around the house, people we recognize in a crowded place, cars in a parking lot, and so on. The number of items in a display or scene, called a set size, affects the difficulty in finding a desired object. The higher the number of distracters, the harder it is to find the target in a display. This is why it’s so hard to find objects in “Where’s Waldo,” “I Spy,” and crossword puzzles.
I also found the concept of RSVP and the attentional blink interesting because I thought it was interesting to learn about the timing of the acts of selection, and how the timing can affect accuracy of identifying target stimuli. Rapid serial visual presentation, or RSVP, is an experimental procedure in which a stream of stimuli appear at one location at a rapid rate, usually 8 per second. During this type of experiment, a subject watches a stream of letters that all appear at the same location in space, and they try to find a number in the stream of letters. The variation in the experiment occurs when the speed of the characters presented changes. The goal being to see how fast the stream can move, with the subject still being able to make accurate decisions. This experiment can be done with photographs of various scenes or objects as well as letters and numbers. The task can also be changed to find two digits instead of one in the stream. The first digit called T1 for target 1, and the second digit called T2 for target 2. According to the textbook, the critical variable is the interval between T1 and T2, the surprising result is if T2 appears 200-300 milliseconds after T1, and if T1 is correctly reported, the subject was likely to miss T2. This is called an attentional blink, because your ability to visually attend to the characters in the RSVP sequence were ‘knocked out’ for a short time, despite the subject’s eyes being open. An attentional blink is the difficulty in perceiving and responding to the second of two target stimuli amid a rapid stream of distracting stimuli if the observer has responded to the first target stimulus within 200-500 milliseconds before the second stimulus is presented. I think it’s interesting that I could miss seeing something even if my eyes were open and I was intentionally looking for the target.
I found visual attention disorders interesting to learn about, as well, because since taking this class I have become interested in maladies and problems concerning vision and the eye. Brain damage that results in complete inattention is close to functional blindness, which is very rare. A visual-field defect is more common. This is when a portion of the visual field with no vision or with abnormal vision, typically resulting from damage to the visual nervous system. If a person loses primary visual cortex in the right hemisphere of the brain, they will be blind on the left side of their visual space. But if the brain damage occurs in the right parietal lobe, that person would have difficulty directing attention to objects on their left side of their visual space. These problems manifest themselves through neglect and extinction. Neglect is the inability to attend to or respond to stimuli in the contralesional visual field-typically on the left field after right parietal damage, and neglect of half the body or half of an object. A contralesional field is the visual field on the opposite side of the brain lesion. Neglect patients usually only see what is to the right of fixation and ignore objects on the left, this can mean eating only food on right side of plate, or shaving only right side of one’s face. Extinction is related to neglect, but it is the inability to perceive a stimulus in the presence of another stimulus, typically in a comparable position in the other visual field. The example used in the book helped me understand this concept better. It said if a neurologist told the patient to focus on her nose, and held a fork in the patient’s “good” (right) visual field, and the patient would be able to identify the fork. Next she would hold a spoon in the “bad” (left) visual field, and the patient would be able to identify the spoon. But if the neurologist held up a fork in one hand and a spoon in the other, the extinction patient would report only the object in the “good”/right field, and the other object would be perceptually “extinguished.”
The concept I found the least interesting to read about in the chapter was change blindness, because I have already learned about this topic in another course, and I know refreshing information is beneficial to better understanding of a subject, but I prefer learning about new concepts. Change blindness is the failure to notice a change between two scenes. If the change doesn’t alter the meaning of the scene, quite large changes can pass unnoticed by the observer. In the 1990’s, Rensink and some colleagues created a different picture memory experiment. They allowed participants to observe one picture at a time, and then it would disappear for 80 milliseconds, and then replaced with a similar picture. The participants were supposed to determine what had changed between the two pictures. The two images were shown back and forth with a blank screen in between the two images. This was done until the observer saw the change or the designated time ran out. In Rensink’s experiment, it took participants several seconds to find the change, and some never spotted it at all. They found that if the blank screen is not shown, the changes are more obvious to spot because the participants experience a kind of apparent motion effect that we learned about in chapter 7, when objects move positions, vanishes, or changes color.
I think the concept of visual search will be the most useful to my understanding of sensation and perception, because we are constantly looking for targets in displays with many distracting elements in our daily lives. As humans we are constantly looking for specific targets in scenes and situations full of distractors, like trying to find your car in the grocery store parking lot, or looking for friends in the crowds at the Iowa State Fair. The number of items in the display or scene (set size), can affect the difficulty of this task, for instance, the greater the amount of cars in the parking lot, or people at the Fair, the more difficult it is to find your target (your car, or your friends).
I would like more information concerning visual search and experiments related to this topic, because I found it especially interesting to learn about. I think that more information about how our visual nervous system can more quickly identify targets from distractors would further my understanding of the concept.
I would also like more information about limited-capacity parallel processes, because I don’t think I fully understood the concept while I was reading about it in the textbook. I know that this process is capable of handling many stimuli at one time but that processes each item more slowly as the number of items increases. I think I would have a better grasp on the concept if a more detailed example of this process was given, or an illustration of the concept, perhaps.
Terms: visual search, target, attention, distractor, set size, cueing experiments, reaction time, additional blink, RSVP, rapid serial visual presentation, digits, T1, T2, target 1, target 2, visual attention disorders, vision, eye, complete inattention, visual-field defect, visual field, visual nervous system, primary visual cortex, right hemisphere, left hemisphere, visual space, parietal lobe, neglect, extinction, contralesional, fixation, change blindness, limited-capacity parallel processes
If you like visual search stuff, check out Guided Search Theory by Jeremy Wolfe (author of your text, I think). It is a different formulation of Treisman's Feature Integration Theory. There is also some stuff about Fingers of Instantiation from Pylyshyn. With limited capacity parallel processing, the idea is that you can process things (probably features from the same dimension) in parallel, but if there is no pop-out (e.g., the target is so different from distractors it "jumps" out at you), then you have a parallel processing of items up to a certain point (i.e., amount of items). This is a slightly different theoretical take that postulates that you have parallel processing of information, but it is not unlimited.
The first material I found interesting in chapter 8 was apparent motion. As a kid I loved making "flip books" (I think that's what you call them?). It's when you draw a picture on a bunch of different pieces of paper, but with everyone, whatever is in the picture is moving just a little bit more than the one before it. Apparent motion made me think of this idea that you don't need, necessarily motion between two objects to have them appear to be moving. The rapid movement of one picture to another makes our motion detection cell responds strongly as if the two pictures were smoothly moving. This is a pretty interesting idea considering that all of our animated movies start from this process!
Secondly, I found middle temporal area and Newsome and Pare's monkey research to be very interesting. It is understood that the middle temporal area (MT) is an area in the brain that is important in the perception of motion at least in nonhuman primates. The human's area of concentration of motion has been identified from MRI's. Recent studies have shown that there might be actually two areas of the brain that are motion-sensitive. Newsome and Pare's work with monkeys is very interesting. They first train the monkeys to respond to a correlated dot survey in which either 100%, 50%, or 20% of the dots are moving in the same direction. The monkeys before surgery (fully functioning brains, could recognize 2-3% of the dots that were correlated motion. Then they went in and surgically lesioned the monkeys MT areas. After, in order to identify the direction of the dots, the monkeys needed about 10 times more of the dots to be moving in the same direction. Although, after several weeks of doing the same motion-dot survey, they learned to use other parts of the brain to determine the motion of the dots. Later, another study had a different set of monkeys. The researchers taught them how to discriminate correlated-motion directions. They then went in and poked around the MT area to find grouping of neurons that were responding to one direction of dots. They then would electrically stimulate that area, the monkeys would identify that the dots were moving in the opposite direction that the dots were actually moving. This study demonstrates that the MT is the site of global-motion detection in the visual system. Very interesting study monkeys! At first I didn't like that they were messing around with monkeys brains, but hopefully they weren't hurt in the process!
Thirdly, I found the information on akinetopsia to be very interesting. It is when your MT area is messed up and you have no perception of motion. Although the two cases in the book were from side effects of a prescription antidepressant drug, you can also have injury to the MT area of the brain and have the same problem. Although, the most interesting part, like the monkeys brain, the human brain will find a way to re-direct the neurons to make your motion-processors work again! The brain is an amazing place!
One thing I did not find interesting was the computation of visual motion. I read it, and nothing stuck. It was really confusing and not very helpful in understanding visual motion.
One thing I thought was most important in understanding Sensation and Perception was the study researches did on the monkeys. Their findings were very interesting and really showed an importance of the MT area when detecting motion.
Two topics I would like to further research are reflexive eye movements and akinetopsia.
Terms: akinetopsia, reflexive eye movements, middle temporal area (MT), apparent motion.
The neurophysiological research is interesting. We get a sense of how single neurons respond to motion information, which helps in the overall theories about global motion processing. I think ultimately the best approach is the integration of information that we get from multiple techniques and methodologies. Knowing about the single neuron's response in an area of the brain should be backed up by fMRI studies of that area as a Region of Interest, followed by EEG/ERP motion studies, and of course psychophysical experiments (easier to conduct, quick results). Then you get a sense of how all the information comes together. AND, you get a sense of whether or not the evidence from both the micro and macro levels corroborate one another.
Being a girl from a small town in Iowa, attending the county fair has always been a big part of my life. As an adolescent at the fair, when your parents first allow you to start going off on your own visual shift becomes increasingly important part of life. Visual shift has to do with your brain accessing its retinal array and using selective attention to more easily identify parts of the environment that are highly recognizable. You’re a young person at the fair, the rodeo just ended and you are in need of a few more dollars so that you can go on one more ride. Your mind immediately shifts its attention to searching for your mom, dad, or someone who has recently seen your mom or dad. What fascinates me about this is not the idea that you so quickly and easily can identify these people but the other things that you miss while on this search because your attention is so focused. At one point in my life I had been in a similar situation and completely missed a person that I had walked by who had been carrying a 3 foot snake around their neck, yuck! How could I have possibly missed a giant snake that I was so close too I almost touched it? In relation to this, during that week of class where we had to choose an experiment recently, I choose to do the Visual Search Time as a Function of Background Distracter Set Size and Type experiment. The concept of this experiment was similar only you were not searching a crowd for a parent; you were searching for a target stimulus in a set of distractors. Your brain can search all of those distractors easily and while your brain is scanning each one for the target the brain can do it so fast that it doesn’t actually feel like you’re are searching each distractor or in the case of the county fair, face.
While I can easily understand the concepts of selective attention I had a little more trouble understanding covert and overt attention because the book description relates this to shifts of the eyes. The way I look at it, these eye movement shifts happen a lot yet they do not seem to distract me, therefore I have trouble understanding how this relates to attention, maybe the definitions have been too simplified in the book with not good enough examples. I would like more information on this. I also thought that I had a good understanding of extinction and neglect but am not confused when trying to relate this to sensation and perception. These are the other areas that I would be interesting in learning more about.
While the eyes may always be moving around and trying to find important parts of the environment feature integration theory plays a part in the whole picture of how the brain interprets the world. Feature integration theory, my most important concept to add to my bag of brain tricks for this chapter, by Anne Treisman shows another way in which our brain can be selective when searching for a stimulus. In my mind this has to do with deduction and disregarding useless information and applying the useful information to find the stimulus. The example in the book is that if someone tells you to find a little brown mouse, you do not first search through the red shiny objects you can disregard them right away so that you can more quickly search through items that are small and brown and mousier in general, while doing this though you much be careful because your brain may be quick to create an illusory conjunction. The example of this in the book was also a really reliable one and totally worked on me. The book had you stare at a group of letters, beforehand you knew you would have to remember letters and colors and match them. I stared at the picture and then made my list. I had mixed up the color of the F, which I still believe in my mind was most definitely purple but in reality it was red. How can this be? It turns out that the brain basically soaked up as much info as it could and then when it was forced to recall that same information it could only remember a limited amount and therefore inferred and matched what it new together. I do this all the time when I am looking for a particular picture in a text book. I remember it being specifically in one spot on a page, so I flip through a few times usually only to find out that I was wrong and it was on a right page top left not the bottom right of the left page for example.
The above phenomenon is not terrible but slightly inconvenient, not let’s focus on something our brain does that is actually quite helpful. This topic would be picture memory; this struck me as interesting because of my course in memory and language. It turns out that the brain can easily (like really easily) remember pictures or simple images, literally thousands of them. This connects to memory and language because I remember doing a specific experiment in that class not with pictures but with lists of words, for some reason picking out the words that were not said before was terribly easy. One part of this that scares me a little bit with picture memory links to advertising. If we can so easily remember these pictures it’s no wonder advertisers have no problem selling products. You are looking at a large array of dish washing soaps, which one will you choose, the familiar one that you have seen advertised a million times, whose slogan comes to mind immediately or the no name brand that you have never heard of that has never promised you that it will make your hands silky soft and get all the grease off?
In relation to this is the attentional blink. I did not really find this part very interesting and I think they should have done a better job explaining this, finding a way to make it more interesting. I liked the fish analogy but the process just seems so simple in comparison to the other theories in this chapter that it could not easily capture my attention.
Terms: retinal array, attention, covert attention, selective attention, target, distractor, , feature integration theory, illusory conjunction, Anne Treisman, Visual Search Time as a Function of Background Distracter Set Size and Type experiment, overt attention, extinction, neglect, picture memory, and attentional blink.
Good post. I think the thing I like the most about studying attention is that it is absolutely essential to our lives and we use it constantly, even though sometimes it breaks down and we have trouble attending. What is even more interesting to me is how the brain is able to focus on relevant information (to the task, or via saliency cues) and often able to filter out irrelevant information. There is so much visual information out there, and most of it is irrelevant to our lives and the situations we find ourselves in. The snake is relevant, and involves a survival based control of attention.
found the concepts in the book about the visual search to be interesting because it explained my results of the experiment we did a few weeks ago. We use visual searches all the time without even realizing it. When we find the tooth paste in the bathroom cupboard every day, or even when we are in a crowded place looking for a friend. When using the toothpaste example, the tooth past would be considered the target item, or the thing that we are searching for. Other items that may be in the bathroom cupboard would be considered distractor items. Now we all know that the more items in the bathroom cupboard the harder it may be to find the toothpaste. This is because as the set size, or the number of distractior items, increases the harder it is to find the target item.
I also found the feature search to be interesting because it was also part of the experiment that I did. The feature search is defined as a search for a target defined by a single attribute, such as a salient color or orientation. An example of something being salient would be something that stands out because it is somehow different from the other distractors or targets. Sometimes people will have to engage in a serial self terminating search which would be when you need to examine every single item until you find the target. This is very inefficient but sometimes needs to be done to identify the target. This kind of seems painfully obvious to me but I still think that it is interesting to think about.
I thought the part in the chapter about picture memory was very interesting. The studies that have been done on it are really kinda cool. Rodger Shepard did a study where he showed people 612 pictures for like 2 seconds and then showed them to the people again with random pictures mixed in. He had them try to figure out if they had seen the picture before. He found that the people with 98% correct with their answers, and 90% correct with their answers a week later. This is pretty amazing to me. Harber (1970) got 85% accuracy when doing 2,500 pictures and Standing (1973) got similar results when he showed people 10,000 images. That is a lot of images to remember and it is pretty cool that our brains can remember, recognize and recall that many images when only seeing them for so short of a time.
I didn’t really like the part of the chapter about the feature integration theory by Anne Triesman. I thought it was kind of confusingly written. The feature integration theory is a theory of visual attention that holds that a limited set of basic features can be processed in parallel pre-attentively but that the other properties, including the correct binding of features to objects, require attention.
I think the most important part in the chapter when attempting to understand sensation and perception is probably the stuff about visual search and feature search and understanding how we pick stuff out to attend to
2 things that I would like to learn more about in this chapter would be the disorders of visual attention and visual search and feature search.
Terms: Visual search, target, distractor, set size, feature search, salient, serial self terminating search, feature integration theory, preattentive, picture memory,
Treisman's FIT can be a bit confusing, because others have added so much to it that and found a few issues with it. But it is important in that it is the first theory to have thought about how this stuff and visual search process works and ultimately requires attention in certain instances. The visual attention disorders are interesting. Check out the different types of neglect (representational, object based, etc). Also, check out Balint's syndrome, particularly simultanagnosia. Cheers.
I found the concepts in the book about the visual search to be interesting because it explained my results of the experiment we did a few weeks ago. We use visual searches all the time without even realizing it. When we find the tooth paste in the bathroom cupboard every day, or even when we are in a crowded place looking for a friend. When using the toothpaste example, the tooth past would be considered the target item, or the thing that we are searching for. Other items that may be in the bathroom cupboard would be considered distractor items. Now we all know that the more items in the bathroom cupboard the harder it may be to find the toothpaste. This is because as the set size, or the number of distractior items, increases the harder it is to find the target item.
I also found the feature search to be interesting because it was also part of the experiment that I did. The feature search is defined as a search for a target defined by a single attribute, such as a salient color or orientation. An example of something being salient would be something that stands out because it is somehow different from the other distractors or targets. Sometimes people will have to engage in a serial self terminating search which would be when you need to examine every single item until you find the target. This is very inefficient but sometimes needs to be done to identify the target. This kind of seems painfully obvious to me but I still think that it is interesting to think about.
I thought the part in the chapter about picture memory was very interesting. The studies that have been done on it are really kinda cool. Rodger Shepard did a study where he showed people 612 pictures for like 2 seconds and then showed them to the people again with random pictures mixed in. He had them try to figure out if they had seen the picture before. He found that the people with 98% correct with their answers, and 90% correct with their answers a week later. This is pretty amazing to me. Harber (1970) got 85% accuracy when doing 2,500 pictures and Standing (1973) got similar results when he showed people 10,000 images. That is a lot of images to remember and it is pretty cool that our brains can remember, recognize and recall that many images when only seeing them for so short of a time.
I didn’t really like the part of the chapter about the feature integration theory by Anne Triesman. I thought it was kind of confusingly written. The feature integration theory is a theory of visual attention that holds that a limited set of basic features can be processed in parallel pre-attentively but that the other properties, including the correct binding of features to objects, require attention.
I think the most important part in the chapter when attempting to understand sensation and perception is probably the stuff about visual search and feature search and understanding how we pick stuff out to attend to
2 things that I would like to learn more about in this chapter would be the disorders of visual attention and visual search and feature search.
Terms: Visual search, target, distractor, set size, feature search, salient, serial self terminating search, feature integration theory, preattentive, picture memory,
I found the visual search concepts from the book very interesting. They remind me of my younger years when I had Where's Waldo books. In the books the target is Waldo and all the crazy shenanigans happening around him were distractors. It was definetly harder to find Waldo as number of distractors increased. This is a typical rule of thumb: as the set size increases, it is generally harder to find a target. When searching though the pages, I definetly think that I used spotlight of attention. This is where you shift your point of fixation from one point of attention to another. I would let my eyes sweep across the page in an orderly fashion so that I knew I would cover all portions of the page and would find Waldo in a orderly fashion. The spotlight of attention may apply in other ways like when you let your fixation point grow from a very narrow point until it gets very large. I also remember the last page of the Where's Waldo book was a page of hundreds of fake Waldo's. There was only very slight differences between the fake Waldo's and the real one. This was the hardest Waldo to find and needed to emply a serial self-terminating search where I would eliminate Waldos that did not match. I thought this was interesting because it really made me think about how I use my own types of searches when trying to find objects.
I also thought the disorders of visual attention were interesting. Damage to the pariental lobe cause visual-field defects where patients have no or abnormal vision. If a person experiences damage to the right hemispheres pariental lobe, than they will have vision troubles with their left eye. Some visual-field defect examples are neglect and extinction. When a patient has neglect visual attentition problems, it is like that part of the world does not exist. It can either effect one side of their vision or can effect one side of all objects. Extinction is like a less sever version of neglect where people are not able to perceive stimulus to one side of a fixation point. I thought this was interesting because it is always interesting to hear the worst possible situations.
Roger Shepard's experiement on picture memory was a very impressive example of the human mind. Participants were shown 612 different pictures for about a second each. They were then shown another 612 pictures and asked to identify which pictures they had seen in the first 612. People got 98% correct. I think that this is pretty amazing that people can remember that many things after only seeing them for a brief time period.
I did not really enjoy the topics attentional blindness. I thought it was really common sense. I didn't think Chun's fishing metaphor was very good explanation of how it works, because you may see the target, you cannot catch a second fish in the net without risking the first one swimming out.
I would like to know more about the different parts of the brain that respond strongly to different stimuli.
Terms: Visual search, target, distractor, spotlight of attention, set size,serial self-terminating search, visual-field defect, parietal lobe, neglect, extenction,
I think the cool thing about attentional blindness is that it indicates that we really don't have access to everything in our visual environment that we think we do. This to me indicates that while we think we are consciously aware of everything available to us, it really depends on the situation and we might miss a lot of important information.
I thought chapter 8 was very interesting, and it was hard for me to find something that was uninteresting. The main reason I thought this chapter was interesting was because I could relate very well to the material, and it all seemed really real to me. I also believe attention is a very interesting topic.
One of the most interesting ideas I took from chapter 8 was the information about visual searches. I most likely found this topic to be interesting because during week 7 this was the experiment i chose to do, so i already knew some information about the topic. In most searches someone is looking for a target in a set of distracters. When the set size is larger it is harder for us to find the target because there are more distracters. This would mean our reaction time slows down. Our searchers are efficient when we can focus our attention on the target right away, but our searches are inefficient when we have to look through many of the distracters to find the target. Inefficient searchers can also be a serial self terminating search, where we have to go thought all the information given to us just to fine the one target. Most searches are inefficient, especially if the target and the distracters have the same characteristics. When we are doing feature searches our results are more likely to be efficient because our target would have different characteristics than the distracters, like color.
I also found the information about disorders of visual attention to be interesting. This section was interesting to me because these disorders are very rare. When the right side of the visual cortex is damaged the person will lose sight on the left side. When the parietal lobe is damaged the person will have problems with attention. The problems can either be neglect or extinction. In neglect the person will not pay attention to one have of what is in front of them. If the neglect is on the left side of the visual cortex they will not pay attention to anything on the left but pay attention to things that are on the right. In extinction a person is able to see or pay attention to an object that is in their neglected visual region, but they are not able to determine what the object is. They can only pay attention to the object if it is a salient object. If there is competition between two objects the attention will go to the object in the ipsilesional field (the object that is on the same side of the lesion or damage of the brain).
Another topic I found to be interesting what the information on picture memory and change blindness. This information was interesting to me because I find it fascinating how we can remember pictures so quickly. We are more likely to pay attention to pictures rather than other objects like letters. Also we are very good at remembering these pictures after they have been presented to us then taken away, not only by minutes but by hours, days, and even months. It was also interesting that we can determine very quickly between objects in a picture, like if the picture is of an animal or not. We can do this so quickly that the picture does not even process through our memory, but we can determine what the photograph is and what the objects are in the photograph. When it comes to storing a picture in our memory it only takes seconds. The information I found interesting about change blindness was when two pictures that are similar to one another are presented to us it is harder for us to determine the differences between those two when there is a black screen separating them or if they are presented side by side. It is harder for us to determine the differences because we saccadic, we become vertically blind when there is a change or loss of focus. When the images are presented one after another it is easier for us to determine the differences because we are viewing apparent motion, we can see the change.
If I were have to pick something that was uninteresting in the chapter I would choose the section that was about the physiological basis of attention. This was uninteresting to me because I thought it was making attention harder to understand. It seemed this section was saying that attention comes from many different parts of the brain, which it does, but I thought it could have gone into more detail. I thought this section was an important section to know about and there should have been more information given.
I believe the most important concept to take from chapter 8 that would help in understanding sensation and perception is that without attention we cannot have visual perception. I also believe it is important to know the different types of attention that can be given and how they are play a part in how we visually perceive the world around us. I also believe it is important to know that we are able to give attention to multiple things at once, but when it comes to something we really what to be paying attention to we are able to “tune” other distracters out. Attention does not just come from one area of the brain; it comes from multiple areas of the brain. We cannot have normal visual perception if we cannot pay attention.
After reading chapter 8 I would like to know more about picture memory and change blindness, more about change blindness because I find it interesting that even if the picture are next to one another it is hard for us to determine the differences between them. I would like to know more information on why it is harder for us to determine the difference, but we are so good at remembering pictures that are not similar. I would also like to know more information about the visual disorder known as Balint Syndrome. I would like to know more information about this disorder because it is so rare. I would like to know what exactly a person with this disorder goes through day to day.
Terms: visual searches, target , distracters, set size, reaction time, serial self terminating search, feature searches, visual cortex, parietal lobe, neglect, extinction, ipsilesional field, memory, change blindness, saccadic, vertically blind, apparent motion, visual perception, Balint Syndrome
The change blindness research is interesting because when the same image (minus one feature or plus one additional feature in the next image) flickers back and forth between the two scenes, we often miss this change all together. But, it seems we can remember complex objects pretty easily in our pictoral memory. So, this to me indicates that in some instances we are pretty good and the task and in other occasions we are terrible at it. Thus, we should be skeptical of the veridicality of our perception and memory. Just because you think you see it or remember seeing it, doesn't mean it's there!
Balint's is super interesting and the main symptom with regard to attention is simultanagnosia. Typically, they can only attend to one thing at a time in their environment. So, they might see a cereal box at the grocery store, then they might see the oatmeal, but they only are aware of the existence of (typically) a single item in their environment. Very difficult to get around. My current boss used to work with Balint's patients (bilateral damage to the parietal lobes). She has some amazing stories and videos of what the experience of the visual world is like for these people.
In Chapter 8 I found the concept of selection processes in space really interesting. In psychology, whether in be in Sensation and Perception or Psychological Statistics (I am currently taking this class), you will hear a lot about reaction time. Depending on the class and issue at hand, you may be measuring it, or just talking about it. Reaction time (RT) Is the measure of time that lapses between the time a stimulus is presented and the time that the stimulus is responded to. In a lot of experiments, a stimulus or cue can be presented to a test subject and they will have to determine where this stimulus was presented as fast as they can. Then their RT is measured, sometimes, the test subject’s eye movements will be measured as well to indicate RT. Usually in these types of experiments, SOA or stimulus onset asynchrony is measured as well. This is the measuring of the time between the onset of the first stimulus and the onset of the second stimulus. By doing this, the researcher can measure multiple reaction times, rather than presenting a stimulus and measuring the time of reaction between the presentation of the stimulus and the point that the subject notices the stimulus and then repeating this process all over again. Attention, in some ways, is defined as the movement of our eyes from one fixation point to another. Like mentioned before, experimenters like to measure attention and RT at the same time.
We are all familiar with visual searches, just in a very elementary way. Word searches, find the differences, and “Where’s Waldo”, are scattered among the funny and game pages of almost every newspaper these days. These are just used as time wasters in way. Explained in sensation and perceptions terms and terminology present it to be a bit more complex than we had thought. Visual searches, defined in the text as, looking for a target in a display containing distracting elements, provide a closer approximation of the actions of attention in the real world. In these puzzles found in newspapers, the reader looks for a certain target, whether it be a word, object, or Waldo, but among these correct answers there are distractors everywhere. These can be jumbled letters, a confusing visual scene, or same colors grouped together to make a camouflaging effect. Usually there is a set size in these puzzles, in other words, a number of items in a visual display. The puzzle, “Where’s Waldo” uses salience to their advantage. Salience is the vividness of a stimulus relative to it neighbors. By using the colors red and white, the subject has a hard time distinguishing objects and people from each other, therefore, making the search for Waldo, very difficult.
Picture memory and change blindness was also a very interesting topic. In the book it challenges you to look at the photographs of 16 scenes and memorize them. Then you are instructed to turn the page and pick out the scenes that are repeated in the 16 photographs in that set. I did this, and missed only one scene (I was pretty proud of myself). These tests has been given numerous times in a laboratory setting, but have been altered in the amount of pictures shown, and the differences in individual pictures. With all of these experiments given, it has been concluded that people can understand very rapidly that given enough time, perhaps just seconds, that we can code them into memory in sufficient detail to be able to recognize the object days later. In other words, it doesn’t take our brain long to memorize and recognize changes in objects or scenes. Change blindness happens when it takes some time to notice changes in a visual scene. This is normal, but it shows that large changes in pictures can go unnoticed. I hope I am right when I say this, but Sherlock Holmes was a detective that said to never underestimate the obvious and that the answer could be “right under our noses”. Change blindness is something that would play a role here because you are hiding things “in plain sight”.
The thing that I found least interesting in the chapter was the section about the physiological basis of attention. When they talked about the fusiform face area and para hippocampal place area, I found that to not be as interesting just because it seemed to be really confusing. The addition of fMRI pictures didn’t help me comprehend or understand the material any better, I think it just made it more confusing for the reader. The part that I felt was helpful to understand sensation and perception a little bit better was the section about visual searches. I feel this way because we are all familiar with visual searches but now because of the information in this chapter, know how they use the discipline of sensation and perception to make a game out of it. The producers of such puzzles, use mind tricks and visual tricks to make the game more interesting. I would like to know more about the physiological basis of attention.
TERMS: reaction time, cue, stimulus onset asynchrony, visual searches, target , distractors, salience, change blindness , fusiform face area, para hippocampal place area
The physiological basis of attention is important because it gives us an understanding of the underlying structural basis of attention. We hear so often about the functional purposes of attention, because the experiments conducted are often functional accoutns of attention. However, there can be no functionality without an intact underlying structural architecture (as is evident by patients with damage to these areas). So, the physiololgical basis of attention involves the neurophysiolgical experiments with monkeys (electrodes in the brain), fMRI in humans (regions of interest implicated in attention), and some EEG/ERP for the timecourse measures of attention as well. Pretty difficult to understand at first pass, but there is a lot of research that has been done in the monkey physio world that gives us a better understand. Then our jobs can be to integrate the neurophysio research with the imaging research and the behavioral experiments as well.
Chapter 8 is on attention and scene perception. Attention being any very large set of selective process in the brain to deal with the impossibility of handling all inputs at once. Our nervous system evolving so that we are able to restrict processing to a subset of things, places, ideas or moments in time. This lead to selective attention, the form of attention involved when processing is restricted to a subset of the possible stimuli. Brings to mind when a person is asking if they have your full attention or not.
Within the prospect of attention inlays something I found interesting and reminiscing of childhood. Visual search, the act of looking for a target in a display containing distracting elements; much like the “Where’s Waldo” books I had as a kid. They were testing our visual searching skills though that may not have been their intention. Waldo was the reader’s target, the target being the goal of the visual search. While we had to look through these whole page of chaos to find him. The chaos being the distracter in the visual search; any stimulus other then the intended target, took a lot of attention and visual searching to find him and I still remember pages where I never did find him. I had to grow through all the pages using serial self-terminating search pattern, searching from item-to-item, ending when the target is found. In this case, being Waldo.
Another thing I found interesting, had have found interesting prier is the brains acuteness for detecting faces. Fusiform face area, an area in the fusiform gyrus of human extrastriate cortex that responds preferentially to faces in fMRI studies. As we use faces and expression to communicate with one another more so if we have different languages it’s rather critical. Our brains can pick up faces and our attention is draw to that at times due to. Versus how another part of our brain focuses on places; parahippocampal place area; a region of the cortex in the temporal lobe of humans that appears to respond with particular strength in images of places.
As before in class when change blindness was mention I found it interesting, so when change blindness came up again in chapter 8 I was happy to learn about it. Change blindness being the failure to notice a change between two scenes. If the change does not alter the gist, or meaning of the scene, quite large changes can pass unnoticed. I have a relatively good memory, slight photographic memory when it comes to images maybe, so I found the research done in the 1990s to be very interesting. Looking between the two castles in the chapter I was able to steadily note the differences in the image. While staring at one image, a simple saccatic movement of the eye, and change blindness may occur.
Terms: saccade, parahippocampal place area, attention, visual search, selective attention, target, distractor, Fusiform face area, serial self-terminating search
Good post. Check out 60 minutes tonight for a special segment on Face Blindness (aka prosopagnosia). What happens when the FFA is damaged? It should be interesting to compare what you know from the class and what you've read about it from scientific sources and see how different these sources of info are from the media's presentation of the material.
What I enjoyed most about this chapter was the timing of having to read about attention the week before spring break. Attention is process that selects stimuli for the brain to focus on so that it does not get too overwhelmed. The stimuli selected are known as cues, which can be either correct or incorrect. When the cue is correct, then the person will be able to pay attention faster because of the cue is leading to what the person is intending to pay attention to. The book simplifies this by comparing attention to a “spotlight”. The spotlight example explains that there is a fixation point that we try to pay attention to and as we change fixation point, the spotlight moves over unrelated cues. The theory behind how the fixation point moves varies; the most prominent idea is that our fixation point changes as we shift our eyes from one to the next. If this were true, then the incorrect cues would be the stimuli seen between eye movements from one fixation point to the next.
There are several ways to test attention, but the most interesting design was visual search. In visual search, a situation is set up with built in distractions. Essentially a visual search has the intention to distract participants and to then record the results. To do this, there must be a target and a distractor item. The target item is the goal of the search, or what the participant ultimately wants to pay attention to. In addition to the target, the distractor, anything other than the target, must also be present. I enjoy this experiment because it is very applicable to real life settings. For example right now, my target is to complete this writing assignment, but my distractors are the TV and my roommate talking on the phone. The distractors are causing me to take more time because I am paying attention to incorrect cues, and this is why I am typing a paper so close to the deadline.
The most interesting topic in this chapter is Neglect. Neglect is a visual attention disorder in which the fixation point is fixed on one side, and thus these people typically only experience one side of their visual field. The right side of the visual system is typically the preferred side for neglect patients. The most common test of neglect is to have the patient draw a simple object. Typically they will only draw the right side of the object. But what is most interesting to me is that when the observer draws the patient’s attention to the fact that they didn’t draw the left side then they are able to notice. Therefore it is a case of attention, and not necessarily visual impairment.
I found Balint Syndrome to be a confusing topic because the book did not go into great detail about the disorder. It is a rare condition that occurs when there have been lesions to both hemispheres. People with this condition struggle to reach an object, but I do not understand what specifically it is affected that causes this. These patients also tend to gaze and not have much eye movement. The most interesting, and confusing, aspect is that people with this condition can only attend to one object at a time.
Terms: attention, cues, correct cues, incorrect cues, fixation point, visual search, target, distractor, neglect, visual attention, visual field, balint syndrome.
With Balint's there are 3 main symptoms of the syndrome. There is ocular apraxia, optic ataxia, and simultanagnosia. The first involves the difficulting in the acquisition of fixation of the eyes, the second involves not being able to use visual cues to direct your hand to an object in your visual field, and the third is where you can't use attention to bind the visual world into a coherent whole (so one item attended to at single time). The damage occurs bilaterally to the parietal lobes (attention structural locus). So, with this syndrome you have these symptoms, often co-occuring, which makes it difficult to navigate the visual world. It sounds incredibly disabilitating.
The first thing that was really interesting was visual search because of all that goes along with it and I was able to relate it to my life very easily. I have three sets of keys that I keep on me almost all the time; car keys, dorm keys, and work keys. When I put them all in my work bag or purse they tend to end up in the very bottom. The problem I kept running into years ago was that I would reach into my bag, feel for metal or a key shape and then pull that item out. This got really frustrating when I kept pulling out the wrong keys on the first try. And if I tried to look for my keys my target would be either partially hidden behind/under something else (distractor) or would I would ketch a glimpse of the wrong keys. So to solve this problem I turned my visual search into a feature search by getting lanyards for all three key sets. With each key set having a different color (salience) that can be seen even in a low lit room I can now find them much easier then when they were just floating around in my bag. The second thing was illusory conjunction, mostly because this occurrence of seeing something without really seeing it can be applied in a few other different ways. The one I have the most experience with is when a list of words is read, all themed around Halloween but the word ‘Halloween’ is never said. And yet people will still say that it is one of the words they heard in the list. And the third interesting thing this chapter was change blindness. Only because there used to be quite a few of them in the puzzle books that my grandfather used to get me. Also because I have been known to do this at work sometimes, if the change in our custodial closet doesn’t impact my work or how I get to things I can miss a lot that is stored in there.
Serial self-terminating search, because who’s really going to keep searching for something once they have already found it?
All of the elements that go into people searching for something. We really can’t go a day without looking for something or having our attention pulled in one direction.
The two topics I choose are neglect and simultagnosia. I think the video we watched in class one day really did a good job of explaining neglect but I would like to find out more about what is known about these conditions today.
Terms: visual search, distractor, feature search, salience, illusory conjunction, change blindness, serial self-terminating search, attention, neglect, and simultagnosia.
See previous replies I made to posts about Balint's Syndrome. Hopefully, you can do the in depth topical blog about these disorders/conditions/syndromes.
One of the most fascinating subjects in this week’s chapter was the concept of attentional blink. These phenomena are demonstrated through a procedure known as “RSVP,” or rapid serial visual presentation, in which several stimuli are rapidly presented sequentially at a fixed point. If a participant is asked to identify a target stimulus within the stream of variables, it is not difficult to identify. However, replicated studies show that a second target variable presented 200-500 milliseconds after the initial positive identification falls outside our attentional capacity. This ‘attentional blink’ is somewhat like a saccade or an eyeblink – though our eyes are open and our attention is focused on identifying targets, there is a brief interval during which our visual attentional system turns off following an identification. However, rates of identifying this secondary variable are slightly increased when the second target is presented immediately following the first. This is thought to occur because the attention given to the first target may slightly overlap and catch the ensuing secondary target before the “attentional blink” takes place.
Picture memory and change blindness was another topic that I greatly enjoyed. Over the years, it has been discovered that human beings have an uncanny ability to quickly process and remember numerous images for a great length of time. This is demonstrated by presenting participants with a large number of photos in succession and later having them classify a new set of images as either “old” (previously shown) or “new” (not in the original set of photos). The numbers vary somewhat depending on the study you are referencing, but in general researchers have found that people are able to maintain over 90 percent accuracy when shown a two-second rotation of images numbering not only in the hundreds, but even the thousands! One project even showed that people could classify pictures in a dichotomous category after just 125 milliseconds of exposure per photo! Change blindness shows that despite the ability to remember specific scenes, we are generally poor when it comes to detecting small differences between similar photos. Participants typically take a great deal of time to pick out differences in fine detail and even then they often miss several contrasting features.
A third area I liked was the book’s discussion of visual searches. I don’t think I would’ve enjoyed this part as much if not for being primed by the snow day experiment online a couple of weeks ago. As correlated with my results in that experiment, the book explained that conjunctive searches are much more efficient than disjunctive serial scanning. However, this section also made salient just why multi-feature conjunctive searches are not quite as efficient as simple feature searches. Much of this can be attributed to what has been termed “the binding problem.” This concept is defined as our inability to combine visual features in preattentive processing. The problem occurs because different brain circuits handle perception of these different physical attributes, so a unified object is not perceived until we specifically attend to that particular object.
I thought the least interesting section of the chapter was the portion on neglect. Yes, the topic itself is quite interesting, but because they did not have much to say beyond a direct cause and effect – brain lesions can cause inattention to contralesional visual stimuli. That was basically all that was said. However, I would enjoy learning more about neglect and also attentional blink in class. I believe the most important thing I learned in this chapter as it relates to sensation and perception is that vision alone is nothing without an active brain behind it to attend to specific features of an environment.
Terms: attentional blink, rapid serial visual presentation (RSVP), picture memory, change blindness, visual search, feature search, conjunction, binding problem, preattentive stage, neglect, contralesional
Hopefully, you did your topical blog on neglect and different types of neglect and potential neural candidates for the locus of this damage. Good initial post.
The cueing experiments that used reaction time to test attention were pretty interesting to me. I found them interesting because the researchers changed things in hopes to either speed up or slow down ones reaction time and those things worked. For example when participants in the research were given valid cues their reaction time was faster than when they were given invalid cues. That was a testament right away to the fact that human can not give attention to everything at the same time. It was also interesting when the research was done using stimulus onset asynchrony. Depending on the time that the cue was given reaction time changed also.
Going along with the fact that I liked the cueing experiments I also liked the visual search experiments also. In a visual search you are looking for a specific target in the midst of other distracting elements. Distractors are labeled as anything that is in the environment that is not the target. Visuals searches are much more comparable to the real world than cues. It is pretty amazing to think about all of the visual searches that we do on a day to day basis. The one I hate the most is looking for my keys!
Repetition blindness was also a pretty interesting topic. This starts with rapid serial visual presentation or RSVP. This is a procedure in which streams of stimuli are presented at a rapid rate. Repetition blindness comes when the same stimulus is shown more than once but the times it is shown are too close together. What I get from the description of repetition blindness is that we are so ready to identify stimulus that when we see it the first time we sound the alarm. The problem is when that stimuli comes again are alarm is still going off so we don’t pick up on it a second time. I wonder how close is too close.
What I found to be the least interesting in the chapter was the section that talked about attentional selection. The section kind of intimidated me out of the gate because of the big vocabulary words that it began with Fusiform face area and Parahippocampal place area. What those two words mean are that there is an area that responds more to faces and there is also an area that responds more to images of places. Although I understood what it was saying I really did not find this section to be of much interest to me.
The most useful thing this chapter tells about sensation and perception is that it helps us understand what attention is. Here we learned that attention is not one single thing. We learn that the nervous system has a couple different mechanisms that restrict attentional processes to subsets. Attention can be covert, overt, divided, or sustained. Learning that there are so many differences in what make up attention really broadened my knowledge of what attention actually is.
Finally indicate two topics or concepts that you might like more information about.
Like basically all of the things that I have read about in the book this far there are disorders in the way that things are felt or perceived. The disorders in this section were interesting to me and I would love to learn more about them. The disorder that stood out the most to me was neglect. Neglect is when someone does not respond to visual stimuli in the contralesional field. A contralesional field is the field that is opposite of the brain lesion. We saw this in the video we watched in class. I would love to learn more.
The other topic I would like to learn more about was picture memory and change blindness. Research on picture memory shows that we are pretty good at remembering pictures we have viewed. I am pretty interested in learning what the drop off point is for things like this. Also, with change blindness I would just to learn more about it because I always struggle when you have to pick out changes in pictures and stuff.
Key terms: cue, reaction time, visual search, distractors, rsvp, repetition blindnessm attention, fusiform face area, parahippocampal place area, neglect, contralesional field, change blindness.
Good initial post. Change blindness is pretty interesting and they have done some more work on it, but also it has kind of been researched so much, that it would be hard to do much more with it. But, maybe you can check some more stuff out for your topical blog post.
After reading Chapter 8, I felt I had a better understanding on what attention and also selective attention was about. The first thing I enjoyed reading about was what exactly a visual search is. I found that a visual search is looking for a target in a display containing distracting elements. A target is the goal of a visual search and a distractor is what we consider any stimulus other than the target. The book gave an excellent example of this of the classic children’s book Where’s Waldo. I looked through this books for hours when I was younger, I believe it gave me a better understanding of attention to detail. However you can use a visual search is everyday life from looking for someone while walking through the halls of UNI to finding a book on a shelf. The second thing I enjoyed reading about was Balint syndrome. Balint syndrome has three major symptoms, the patients spatial localization abilities are great reduced, they cannot move their eyes very much, and most importantly, behave as if they can only see one object at a time, otherwise known as simultagnosia. The third item I found enjoyable to read was picture memory. Individuals who have picture memory can remember thousands of images after only a second or two of exposure to the image.
The most interesting topic in chapter 8 was the topic of a visual-field defect. A visual-field defect is a portion of the visual field with no vision or with abnormal vision which results from damage to the visual nervous system. Something I did not find very interesting was the cell communication in regards to attention. I had trough understanding was response enhancement was, I believe it means now the effect of attention on the response of a neuron, which is responding to an attended stimulus. However I did understand that sharper tuning meant that the attention could respond more precisely. Visual search in general I believe is the most important subject when reading this chapter. Visual search is so vital to our visual perception that without it, we wouldn’t be able to find our apples at the store we were looking for, or see your groom’s face when you walk down the aisle. The two subjects I would be interested in doing more research are photographic memory and change blindness.
Terms: attention, selective attention, target, visual search, distractor, balint syndrome, simultagnosia, picture memory, response enhancement, visual-field defect, change blindness, visual perception.
Hopefullly you check out more info on CB and picture memory for your topical blog.
The three things I will take away from this chapter is first attentional blink. Attentional blink, according to the text, is the difficulty in perceiving and responding to the second of the two target stimuli amid a rapid stream of distracting stimuli if the observer has responded to the first target stimulus within 200 to 500 milliseconds before the second stimulus is presented. An example is your vision acts as if you were knocked out and you were just coming to and your vision goes from blurry to clear slowly, your vision slowly focuses the in the second object in that type of manner. I just thought it was interesting because it was new vocabulary for me, and it just drew my interest. Another thing I thought was interesting was rapid serial visual presentation (RSVP). RSVP, according to the text, is an experimental procedure in which stimuli appear in a stream at one location, usually the fixation point, at a rapid rate, usually around eight per second. An example of this is they show you s string of letters or characters in the same location and ask you to if you to detect if there is a certain letter or character in that string. I just thought this was interesting because I have never heard of it before and I was just curious what it was exactly. Lastly I thought simultagnosia was interesting. Simultagnosia is an inability to perceive more than one object at a time. Simultagnosia is a consequence of bilateral damage to the parietal lobes. I always find these type of disorders amazing, because you truly see what little changes in the brain can produce such a drastic result.
The thing I found least interesting was the first part of the chapter. The reason being is because it was a lot of review information I had from previous classes, so I found myself getting bored. The chapter got more and more interesting as I got further into it but the first part was a bit of a drag.
The thing that I read in this chapter that I think will be most useful in understanding sensation and perception is truly understanding the importance of the brain and your vision as a team. It is just amazing to see some of these major defects that can occur in your vision due to brain damage. I understand your brain controls everything and this should be no surprise, but I think it helps you understand the complexity of our brains.
Topics I would like to know more about- Simultagnosia, and change blindness.
Terms- attentional blink, rapid serial visual presentation, Simultagnosia, and change blindness.
What was the first part of the chapter on again? You've been exposed to it before and it was just over-done for you? Check out previous posts on Balint's syndrome. Also, if you really like the topic you can do your topical blog on it it find out more info.
Chapter eight dealt with attention and scene perception. One of the most intriguing concepts I found interest in was based on the word search. A feature search is finding a specific target characterized by some specific attribute. This can be detected by color, shape, orientation, or any specific identifiable difference amongst a group of similar figures. There have been different research and experimental designs to help detect reaction time in finding these various search objects. When someone looks to identify a difference in objects in a research design, they may very well clearly identify the specific targeted object with great ease. In this instance, the highly identifiable distinction is known as salient. Another form of search includes the serial self-terminating search. This type of search deals with an order of various items that are organized one after the other. To help clarify this idea, imagine someone with a flashcard that shows a particular target that is supposed to be the primary focus of observation. Then a repeated visual of different, but possibly similar target shapes are exposed. The observer is to detect the specific target among all the mixture of other flashcards. Sometimes this can be easily done and identifying the target in a jumble of cards. Other times it may be much more difficult to positively identify the target which we were previous exposed to. Similarly, exposure to a target that is much more common and previously exposed through life experience makes the observation with greater ease. The instance from the book gives a nice example of someone trying to identify a target in Chinese lettering. If there is no previous knowledge or exposure to the Chinese lettering or word system, these targets present a much higher difficulty level in determining the target to be identified. If there is, however, some sort of previous exposure or relation to the target the use of guided search is very beneficial. Using a type of schema in acknowledging what a particular target of focus looks like and its accompanying characteristics are make for a higher probability that you will identify the object, or at least much more likely to identify that target. I find these types of “searches” interesting because of how our attention is focused. This might also deal a great deal with the selective attention to cues in identification of the target. With select attention, we pay attention to one or maybe two particular things. For example, while reading the concepts and trying to identify certain targets as given through visual images in the text, I am primarily focused on the task at hand. There are many other outside visuals and distractions that would make this hard to do without selective attention. It is a way to narrowly focus in on something visually. This concept is used every day by individuals, whether they are aware of it or not. Walking across the street on the way to class, for instance, depicts selective attention. The focus to check both ways for oncoming traffic and avoid an accident is one example of where we use selective attention. All other things in our surrounding visual field is almost negated because of this.
Another term from the chapter I took interest in was neglect. Some people’s visual attention is restricted and they are not able to respond to stimuli in the contralesional visual field. There may be a problem present where only half of a picture is present. Someone who is experiencing this neglect might only draw half a picture when attempting to draw an exact replica of some object. People suffering from a stroke might be placed into this category of neglect from one side of the body. If somebody has a lesion on the right side of their brain, the left section will be the neglected portion of the visual field and vice versa. This is identified as the constralesional field. While this presents a serious problem for individuals and interfering with difficulties in everyday life, I find this an interesting thing to learn about. I believe neglect is an interesting topic because of how it presents such a different look on scene perception from what most people understand. There is a great deal of abnormalities and defects that I am unable to clearly relate to, so it is interesting to learn what some other people deal with and how they perceive a different sense of sensation and perception than I do.
Another very interesting thing I learned from the chapter was about the picture memory and change blindness. There appeared to be a highly substantial percentage of correct responses from participants in research done on picture images in identifying a set of images and determining whether a new set incorporated same pictures or new pictures. More interesting though is the change blindness. Sometimes when we see a picture of an object and look at a very similar picture of the same object with minor features differentiating it, they go unnoticed. I have always found interest in these because of magazines that use this concept to test the visual attention of people. My family and I used to have mini competitions to see who could identify all the changes from two pictures. Even when the two pictures are present together, one on top of the other on the same page; it is still often very difficult to determine the changes within the picture! For this reason, I believe this is the most important piece of information in dealing with sensation and perception. If there are definite observable changes made from one image to the next and we are unable to identify these it shows how sometimes the brain is tricked into believing a false idea. This can be said for the eye witness identification lecture, how sometimes things seem one way but we are falsely led to believe something else. There are multiple things in what we perceive that go unnoticed. It is one great piece of information to help understand concepts in where we place our attention that still go without identification.
The thing I found least interesting from the chapter was how attention could enhance neural activity. I didn’t relate to this paragraph as easily as I did with the other concepts. It was also a pretty short paragraph and didn’t expand on the information fully, so I had a more difficult time grasping the whole concept of what was trying to be stated. If I had to pick two topics to research for further investigation, one might be the enhancement of neural activity and attention, just to help more easily identify the idea of what the book was teaching. The other term I would also like to learn more about is extinction. Since I found interest in neglect and the section that the book presented on this topic, extinction would be a related topic that I could learn more about.
Terms: feature search, salient, guided search, selective attention, neglect, contralesional field, change blindness.
Check out some work on biased competition (neural theory of attention) by Sabina Kastner (Princeton). Her group has done a lot of fMRI research looking at what happens to the BOLD signal when you have competition between simulataneously displayed objects in your visual field. Pretty interesting stuff.
My interesting finding in the book would have to be about attention. Attention is any of the very large set of selective processes in the brain. Why would I not choose attention as one of my most interesting findings in the book, it is very important to the visual system. To handle the impossibility of dealing with all inputs at once, the nervous system has developed mechanisms that are capable of restricting a process of the dividing up of things, places, ideas, or moments in time. There are many different things to consider so we will start with the different varieties of attention. Attention can be overt or covert. The overt attentional shift is a shift of attention accompanied by corresponding movements of the eyes. Someone with an overt attentional shift will fixate on a single object. Covert is obviously the opposite of overt. A person who is engaging in covert attentional shift is not only fixating their eyes on one object but then moving their attention to another. If you can do both at the same time, you are engaging in divided attention. The form of attention involved when processing is restricted to a subset of the possible stimuli is called selective attention. Attention can be multi-model. Attention varies over time as well as space. In the attentional-blink paradigm, this is my second interesting topic, observers search for two items in a rapid stream of stimuli that appear at fixation. Attention to the first target makes it hard to find the second if the second appears within 200 to 500 ms of the first. When two identical items appear in the stream of stimuli, a different phenomenon, repetition blindness, makes it hard to detect the second instance. I did experiment after experiment and I was having troubles after the 5th and 6th time picking out letters.
One thing that I found least interesting was change blindness which is the failure to notice a change between two scenes. If the change does not alter the gist, or meaning, of the scene, quite large changes can pass unnoticed. Yeah this is interesting but not as interesting as the things I had never heard of before. I found this topic really funny. I like to go on youtube and watch all the videos that they provide that show change blindness. Number two is spatial layout because I guess there wasn’t much on it in the book. I feel that I have learned a lot about spatial layout in my art classes. How we view the objects that were just put in front of we and we have to draw. It is our own imagination that gets to decide if the object is open or closed, rough or smooth. Spatial layout is a description of the structure of a scene without reference to the identity of specific objects in the scene.
Psychology is all about being observant and seeing view points from all angles. When we learn about the attention and scene perception of the visual system we are expanding on our deep understanding of the human mind, body and spirit.
I would like to learn more about the rapid serial visual presentation (RSVP) which is an experimental procedure in which stimuli appear in a stream at one location, typically the point of fixation, at a rapid rate. I also would like to learn more about fusiform face area which is the area in the fusiform gyrus of human extrastriate cortex that responds preferentially to faces in fMRI studies and the one that responds to places. The attention selection that is specific to places is the parahippocampal place area, this selection focuses on the big picture instead of a single object.
Terms: Attention, visual system, attentional-blink paradigm, covert attentional shift, divided attention, selective attention, overt attentional shift, change blindness, spatial layout, the rapid serial visual presentation (RSVP), parahippocampal place area, fusiform face area
Check out 60 Minutes tonight on CBS. They are having a Face Blindness segment (aka prosopagnosia). Surely they will have some info on why this happens, but it will be interesting to see the difference between the dissemination of this information via scientific versus media-based sources. Cheers.
Attention and scene perception is the main focus of chapter eight. Attention in general was a topic of interest to me. When we think of attention it’s usually focusing on a task that is presented. Attention can mean so much more than that though. The book’s definition of attention is any of a very large set of selective processes in the brain. To deal with the impossibility of handling all inputs once, the nervous system has evolved mechanisms that are able to restrict processing to a subset of things, places, ideas, or moments in time. What that long definition is basically say is that we have different types of attention that we use in different situations. We can have overt attention; which is directing a sense organ to a stimulus. Covert attention which is fixating your eyes on one thing while directing your attention to something else. Divided attention is doing one task while still being aware of your surrounds senses. Sustained attention is anticipating something to happen. Finally, selective attention is the most important. This is when we form our attention to one thing in the midst of many. All these definitions were interesting to me because you never really think deeply about what you are paying attention to. We as people are so unaware at the power of our brain and how much it actually goes through without us knowing.
Another thing I found interesting was illusory conjunctions. These are erroneous combinations of two features in a visual scene. The book had a great example of a bunch of letters mixed up. Each letter had its own color and you were to stare at it for a couple of seconds and then flip the page. After that, you were to try and remember each letter and what color it was. We only have so much short term memory, so more than likely you can’t remember them all. What happens to most peoples is they remember a letter and a color that was present and their brain tells them to combine those two things. So we think we remember those two things were together but in reality our brain was just trying to figure it out and they weren’t really together. The brain forms these images through saccades; which are a bunch of blurry snapshots our eyes take while looking at a picture. Our brain then puts those images together to form what we think we saw. This image is not always correct when we don’t have that much time to pay attention and mesmerize something. I can relate to this, for example, when you play one of those memorization games like brain age for the Nintendo. They ask you to remember words or shapes for a small amount of time and then to report what you saw back. Time after time I would swear I saw something that was actually there so figuring out why that happens is really eye opening.
One final thing I found interesting was change blindness. This occurs when a person fails to notice a change between two scenes. If the change does not alter the gist, or meaning, of the scene, quite large changes can pass unnoticed. You can find these kinds of images all the time in magazines. They’re little games in which you have two images and you have to spot the differences. You think it would be easy but such little changes can go unnoticed. For some this can come easier than others. Hyper attentive people seem to notice these changes so fast while. For me personally, I don’t tend to notice little changes too quickly.
There wasn’t anything about this chapter that I didn’t like this week. All the information was so straight forward and easy to understand. Some other things that I found interesting in the chapter were the parts about neglect, extinction, and Balint syndrome. These disabilities would really affect the way we pay attention to things because we don’t get to see the whole picture.
The thing that will be useful to me in this class that I learned would have to be the way we pay attention to things. When we pay attention to something, we fixate on that object and almost ignore the rest of the things going on. Our eyes are snapping pictures (saccades) and we also are getting two different images from each eye. So it’s up to our brain to put it all together to create one solid image. This is such a good thing to know because this why everyone sees things in a different way depending on the situation each person is in. Someone who glances at an object for a couple of seconds is going to see something different than someone who stares and an object for a couple of minutes. Our brain does the best it can with the information it is presented with and I find that to amazing.
Two topics I would like to learn more about would be response enhancement/sharper tuning and rapid serial visual presentation.
Terms: Neglect, balint syndrome, extinction, saccades, response enhancement, sharper tuning, rapid serial visual presentation, change blindness, attention, selective attention, divided attention, sustained attention, overt attention, covet attention illusionary conjunctions.
Check out some stuff about Guided Search Theory (Wolfe). That will get at the sharper tuning kind of material.
What first interested me in this chapter was the metaphorical explanation of attention. A specific example of this would be the “spotlight” of attention. Analogies are often nice for general explanations, but do not completely satisfy the entire concept in is representing. They can also be basis for hypotheses. This spotlight analogy is especially intriguing to me. If attention is a spotlight, is it always on? If so, does it always have to be directed towards the present environment, or could it be shone inside of the brain; thus being the eye of consciousness? The idea of attention being the eye of consciousness is fascinating, but it strays from the chapter. There are also other theories outlying how attention works. Another metaphor is a zoom lens of a camera, where attention is very broad at a new environment of stimuli, but it quickly zooms in (focuses) to more appealing or important stimuli. Another theory is that our attention is always on important stimuli, but our focusing point is directed towards other areas to fill in our mental representation of the environment. When another novel stimulus is presented, the previous attended stimulus “melts away” in attention, and it then focuses on the new stimulus.
Another topic of interest was visual search. Visual search is a topic of research that reveals very intimate information about the cognitive process of attention. The variables are very complex in scope, and fairly difficult to describe in detail. However, the basic gist of the findings of visual search research is that when looking for a specific object in an array of other objects, if the desired object stands out, it is very easy to find, even if surrounded by many other objects. On the other hand, if the object doesn’t stand out, attention is given to each object individually, in a serial fashion. If the number of other objects increases, so does the reaction time in finding the desired object. Importantly, the research is highly controlled, and most objects in the natural world tend to stand out.
Finally, the most interesting topic in this chapter was how attention can affect our perception of reality. This relates with Dr. MacLin’s research on witness identification. While we search for an item, it automatically becomes the subject, and (unless attention in undergoing serial search) all other objects become the background. This can easily be changed by what item attention is geared to. Adhering to quite some amount of speculation, I speculate that attention is heavily based upon memory. Even more than attention changing in response to accumulating experience (learning what stimuli are important), memory must have some sort of concept of a previous experienced stimulus, and all knowledge related to this concept is connected to this core archetype. This conglomeration of information of a stimulus is used in attention for making it much more effective. Knowing more about the stimulus makes is much easier to find. Even though most people know what a tumor is, and have a basic idea of what it looks like, a doctor would be much more rapid and accurate in finding a tumor. Experience shapes what we know; and thus, shapes what we look for.
Finding a section that I don’t like is very hard for me. I could reach a bit and come up with a basic answer; but frankly, I thoroughly enjoyed this chapter. I personally enjoyed the attention area more than the scene perception, but both were very intriguing.
Terms: spotlight of attention, visual search, etc.
Check out some information on visual spatial crowding. This is basically the research that informs how people find tumors from noise in different types of radiographic images (x-rays, etc.). Attention and memory are very inter-related, and you basically have to disentangle them based on the timing of the stimulus and when it appears and goes aware from our our visual awareness.
Chapter 8- Perceiving Motion
After reading chapter 8 I found the following topics to be interesting; motion functions, comparing real and apparent motion, and behavioral demonstration of Corollory Discharge Theory.
The first topic of motion functions was interesting to learn because it helps us understand events in our environment. We perceive movement stimuli in our environment when we are moving (example: sport players are moving observers and see moving stimuli (teammates or opponents). Motion perception in daily life is important to understand because we use it to navigate and know what is going on around us. If we have troubles with motion perception we might not be able to follow dialogue because you couldn’t see motions of face and mouth.
The second topic of comparing real and apparent motion is interesting because the experiment showed that the client compared the apparent motion similar to the real motion. The client had dots moving in the real motion back and forth, and the second apparent motion the dots flashed looking like it was moving. However, it was not moving but it perceived to be moving so the person said it was similar and in the brain it showed it to trigger similar areas. This is important to understand research in perceiving moving things.
The third topic I found interesting was the behavioral demonstration of Corollory Discharge Theory. I did the demonstration in the book that said to focus on something in front of you and gently pushing back and forth on the side of your eyelid. What happened was that it seems that there was a motion perception even when there was no motion across the retina. The object wasn’t moving, the eye was trying to stay still but there was pressure from pushing the eyelid that the muscle was trying to keep the eye in place. The Corollory is easier to understand once you do the demonstration and it is really neat!
What I didn’t find interesting was The Aperture problem - When I first read about this I did not quite understand it because it is when the stimulus sweeps across the retina and activates directionally neurons to fire. Then I looked over the diagrams once again and read the section explaining how it works, and now I do understand how receptive field corresponds with the field of view directionally.
The most useful information I found was linking the brain activity and biological motion. This research showed the they used transcranial magnetic stimulation on the brains to deactivate parts of the brain or studied brains of animals to see what activity was used for motion. The diagrams and research showed how there is special parts of the brain used and activated for biological motion.
The topics I want to learn more about are how we perceive events and the animal survival research and how they perceive motion like/or different from humans.
Chapter 8 in my book is titled Attention and Scene Perception. Attention is described as many different selective processes in the brain.
I really liked learning about attentional blink. I did not expect the definition at all because I thought this had something to do with the blinking of your eyes. Boy was I wrong. Attentional blink is the process by which your mind is not able to perceive and respond to more than one thing at a time when in a chaotic situation. This makes sense to me because I know that I miss things in my chaotic room at the daycare! I can’t always be expected to perceive and respond to things I don’t see because I am too crazy doing other things.
I was interested in learning about neglect and extinction in this chapter. I was very confused by these two terms when I first scanned over the page because I didn’t know how they related to attention or scene perception. After reading through, I feel I have a better understanding of what we are talking about. Neglect in visual attention is the same in that of a child. If you neglect something for an extended period of time, it becomes worn and not as functional to the point of extinction. I thought this was cool because I never would have put these concepts to the terms of visual attention but they definitely helped in my understanding.
I liked the concept of change blindness. This was interesting to me because its another one of those things I see everyday but never knew there was science behind it. Change blindness is a concept that is defined as a failure to see a change between two different scenes. Basically, to me, it’s one of those “see the differences” type puzzles that you see in magazines. I didn’t know that people had disorders because they can’t do this. That is super crazy. I liked how the book said that you are blind when your eyes don’t have a saccade moment. That is so weird to me but it also makes sense! I want to look more into change blindness in my topical blog and maybe even do some examples!
This chapter really wasn’t as interesting to me as some of the previous ones. Yet again, there was a lot of science stuff throughout the chapter and I am just not good with my biology. There was a section that was about responses of a cell in the brain. I don’t think it was that I didn’t like it but more that I didn’t understand it. Sometimes I find this book hard to understand and I wish I had face to face time to sit and go over some of the concepts listed in this book.
I feel that knowing the different terms of attention and how attention can be altered is very important to sensation and perception. After-all, your attention span is helpful in seeing what all you do perceive and respond to.
Attentional Blink, Neglect, Extinction, Change Blindness