Please read chapter 8. After reading chapter 8, please respond to the following questions:
What were two things from the chapter that you found interesting? Why were they interesting to you? Which two things did you find the least interesting? Why? What did you read in the chapter that you think will be most useful to in understanding the history of psychology? Finally indicate two topics or concepts that you would like me to cover in more depth in class.
Include a list of the terms and concepts you used in your post. (example - Terms: positive reinforcer, extinction, reinforcer, discriminative stimulus...)
Let me know if you have any questions,
--Dr. M
There are many types of attention, but the main kind is selective attention. Attention is any of the very large set of selective processes in the brain. To deal with the impossibility of handling all inputs at one, the nervous system has evolved mechanisms that are able to restrict processing to a subset of things, places, ideas, or moments in time. Overt attention usually refers to directing a sense organ at a stimulus—fixating the eyes on a single word, for example. If you point your eyes at a page while directing attention to a person of interest off to the left, you are engaging in covert attention. Reading some type of text while continuing to be aware of music playing in the room is an example of divided attention. Watching the pot to note the moment the water begins to boil is sustained attention. When it comes to selective attention this involves processing that is restricted to a subset of the possible stimuli.
The first thing I found interesting is the concept of perceiving and understanding scenes. Pictures can be understood very rapidly and that, given enough time, perhaps a second, we can code them into memory in sufficient detail to be able to recognize them days later. There is a phenomenon called 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. If the blank screen between the two images is removed, the changes are obvious because observers experience a kind of apparent motion when an object changes position disappears or changes color. We can actually eliminate the need for a blank screen if the change is made while the eyes are moving. We are virtually blind during an abrupt (saccadic) eye movement. When it comes to local and global approaches to scene recognition there is covert and overt attentional shift. Covert attentional shifts enable us to process something like 20-30 objects per second. This is much faster than the three to four objects per second that can be fixated with over movements of the eyes. Covert attentional shifts don’t change which part of the world falls on the fovea, so we wouldn’t be fixating each of these objects. Covert is a shift of attention in the absence of corresponding movements of the eye, whereas over is accompanied by corresponding movements of the eye. In addition the spatial layout of the scene is not just another object to be attended. Spatial layout means the overall structure of the scene (i.e., enclosed, open, rough, smooth) without reference to the identity of specific objects in the scene. The phenomena like change blindness are important because they show us the gap between perception and reality. Moreover, picture memory experiments show that people can remember thousands of images after only a second or two of exposure to each. In contrast, change blindness experiments show that people can miss large changes in scenes if those changes do not markedly alter the meaning of the scene. Furthermore, perception of scenes may be the result of a combination of local attention to objects and a global ability to glean some information about, for example, the layout of a scene. We may see a sort of theory made up of the products of these two processes. Most of the time this fairly sketchy theory is adequate because we can rapidly check the world to determine if the chari, the book, and the desk are still there.
The second thing I found intriguing was physiological basis of attention. Attentional selection can also be used to perform one type of specialized processing rather than another. For instance, fMRI has shown that different parts of the human brain are especially important in the processing of faces (the fusiform face area) and places in the papahippocampal place area. Fusiform face area is an area in the fusiform gyrus of human extrastriate cortex that responds preferentially to faces in fMRI studies. Whereas, papahippocampal place areas is a region of cortex in the temporal lobe of humans that appears to respond with particular strength to images of places as opposed to isolated objects. For example, if subjects view an image of a face superimposed over an image of a house, the face area becomes more active when the subject is attending to the face, and the place area becomes more active when the subject is attending to the house. Moreover, when it comes to attention and single cells there is a concept called response enhancement which is an effect of attention on the response of a neuron in which the neuron responding to an attended stimulus gives a bigger response. The effect of attention on the response of a neuron in which the neuron responds more precisely, For example, a neuron that response to lines with orientations from -20 degrees to +20 degrees might come to respond to +/- degree lines which is known as sharper tuning. The attention changes the preferences of a neuron. A cell that was initially tuned to vertical lines might come to respond better to a different orientation under the influence of attention. The best evidence for a change in the fundamental preferences of a neuron comes from studies of its preferences in space—that is, the size and shape of a neuron’s receptive field. If cells are restricting their processing to the object of attention, then sensitivity to neighboring items might be reduced as resources are withdrawn from them. This prediction is borne out: mapping the effects of attention reveals inhibition surrounding the object of attention.
One thing I found least interesting was the visual search because it was not very important information to me. Visual search experiments provide a closer approximation of the actions of attention in the real world. In a typical visual search experiment, the observer looks for a target item among distractor items. The target is the goal of a visual search. The distractor is any stimulus other than the target. In addition there is a set size, which is the number of items in the visual display. It is harder to find a target as the number of items increases. Furthermore, feature searches are efficient; it deals with the search for a target that is defined by a single attribute, such as a salient color or orientation. Salience is the vividness of a stimulus relative to its neighbors. In the visual attention, there is a process of multiple stimuli at the same time which is called parallel. When a task involves a serial self-terminating search, in which items are examined one after another (serially) either until the target is found or until all items have been checked. Usually basic features can be used to narrow down a search, even if they cannot eliminate all distractions. This is known as guided search, where attention can be restricted to a subset of possible items on the basis of information about the target item’s basic features (i.e., its color). The search for a target defined by the presence of two or more attributes is known a conjunction search. Each distractor shares two features with target, but the target is still easy to find because we can guide our attention to the right conjunction of features. Moreover, one way to understand the need for attention is to consider what is known as the binding problem. Binding problem is the challenge of tying different attributes of visual stimuli (i.e., color, orientation, motion) which are handled by different brain circuits, to the appropriate object so that we perceive a unified object (i.e., red, vertical, moving right). We might be able to analyze a collection of basic features in a preattentive stave of processing, but we won’t know how those features are bound together until we attend to the object. This is the processing of a stimulus before selective attention is deployed to that stimulus. Furthermore, Anne Treisman’s feature integration theory of visual attention holds that a limited set of basic features can be processed in parallel, preattentively, but that other properties, including the correct binding of features to objects, require attention. Therefore, if you’ve experienced an illusory conjunction, which is a false combination of the feature from two or more different objects. For example, seeing a red X when the display contains red letters and X’s but no red X’s.
Another thing I found least interesting was the RSVP and Attentional blink. When looking at a stream of letters that all appear at the same location in space, showing the stimuli in this way is known as rapid serial visual presentation (RSVP). RESVP is an experimental procedure in which stimuli appear in a stream at one location (typically the point of fixation) at a rapid rate (typically about 8 per second). We are trying to decide if there is an X in the stream of letters. There is a phenomenon known at attentional blink which is our ability to visually attend to the characters in the RSVP sequence were temporarily knocked out, even through our eyes remain wide open. In addition, it’s 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. For example, Marvin Chun’s fishing metaphor for attentional blink. You can see all the stuff in the river as if drifts by, but if you commit to fishing out fish number 1, you will not be able to fish out fish number 2 if that second fish shows up while fish 1 is still in your net. Furthermore, if items are reasonably close together, it turns out to be surprisingly difficult to determine if you have seen one or two of a letter, work, or picture. This is known as repetition blindness which is the failure to detect the second occurrence of a letter, word, or picture in a rapidly presented stream of stimuli when the second occurrence falls within 200-500 milliseconds of the first.
I think perceiving and understanding scenes would be most useful to understanding the visual system and also attention in general.
The two topics I would like covered in depth are selection in space because I don’t understand the relevance very well and RSVP.
Key Terms: attention, selective attention, visual search, target, distractor, set size, feature search, salience, parallel, serial self-terminating search, guided search, conjunction search, binding problem, preattentive stage, feature integration theory, illusory conjunction, RSVP, attentional blink, repetition blindness, fusiform face area, parahippocampal place area, response enhancement, sharper tuning, change blindness, covert attentional shift, overt attentional shift, spatial layout.
I was really thinking about this phenomenon the other day; you said "There is a phenomenon called 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." I wonder if someone could be trained to notice the differences. We all have grown up reading Highlight magazines that have the whole change blindness games in them and or in People magazine where you have to notice to 10 differences in the photos. Are people in law enforcement taught to notice these drastic changes or other professions that deal with perception?
According to our book attention is not one single thing but a collection of selective processes in the brain. I found it interesting that there are more than one attention processes but it also makes sense that attention is a result of multiple processes. There are some distinctions among these processes. There is overt attention, which refers to directing a sense organ at a stimulus, and covert attention, directing attention besides what you are fixating on. There is also divided attention and sustained attention which are self-explanatory. However, Ch. 8 mostly focuses on selective attention, the form of attention involved when processing is restricted to a subset of the possible stimuli. However, these distinctions are not necessarily mutually exclusive.
The first topic I found interesting was visual search. Visual search is looking for a target in a display containing distracting elements (called distractors). There are a few types of searches are visual system can do. The first is a feature search, a search for a target defined by a single attribute such as a color or orientation. Feature searches are efficient because the target seems to “pop out” of the scene. The second is a serial self-terminating search, a search from item to item ending when a target is found. This type of search is inefficient because it takes much longer to find the target. In the real world it is not always possible to do a feature search because many items may have similar features. For the reason we have the following searches. The third search is a guided search, a search in which attention can be restricted to a subset of possible items on the basis of information about the target item’s basic features. The fourth is a conjunction search, a search for a target defined by the presence of two or more attributes. A conjunction search is not as efficient as a feature search but is more efficient than a serial search. To continue the discussion of attention in relation to features is the feature integration theory. This theory states that a limited set of basic features can be processed in parallel preattentively, but that other properties, including the correct binding of features to objects, requires attention. Part of this theory is something called the preattentive stage which is where processing of a stimulus occurs before selective attention is deployed to that stimulus. In order for attention to work there needs to be binding of features which results in the binding problem. The binding problem is the challenge of tying attributes of visual stimuli to the appropriate object so we perceive a unified item. Sometimes an illusory conjunction can occur because of the binding problem. An illusory conjunction is when a false combination of the features from two or more different objects occurs.
The second topic I found interesting was attentional blink. During this section of the chapter we are talking about the timing of selection. When given a rapid serial visual presentation (RSVP) is an experimental procedure in which stimuli appear in stream at one location at a rapid rate, a phenomenon called attentional blink occurs. Attentional blink is the difficulty in perceiving and responding to the second of two target stimuli amid a rapid stream if the observer has responded to the first target within 200-500ms before the second target is presented. In other words our ability to visually attend to the images was temporarily knocked out. Through a series of experiments on video games it was found that a person improved more on attentional tasks after playing first-shooter video games than those who played Tetris. This suggests that our attentional abilities can be changed by training. Another phenomenon that can occur during an RSVP is repetition blindness. Repetition blindness is a failure to detect the 2nd occurrence of an item when the 2nd occurrence falls within 200-500ms of the 1st.
The topics I found the least interesting were the physiological bases of attention. The book discuses what attention could do physiologically. First, it states that attention could enhance neural activity because neurons that respond to stimuli in that part of the visual field become more active. Second, attention could enhance the processing of a specific type of stimulus through selective attention. Parts of the brain are responsible for responding to different stimuli. For example the fusiform face area is responsible for respond to faces. The parahippocampal place area is responsible for responding to images of places. Attention may also change the responses of a single neuron such as in response enhancement. Response enhancement is when an effect of attention on the response of a neuron in which the neuron responding to an attended stimulus gives a bigger response. A cell might also become more precisely tune through sharper tuning.
I think the most important part of this chapter in understanding the visual system is that we are constantly guessing about what we are seeing. We are not capable of attending to multiple visual objects at once and for that reason we often make inferences about what we are saying. Take for example the phenomenon of change blindness. Change blindness is the failure to notice a change between two scenes. We do not notice changes in items that are not needed to understand the scene. We assume and make inferences on how the scene should look.
The topics I would like to discuss more in class are the various disorders of visual attention.
Terms: attention, overt attention, covert attention, divided attention, sustained attention, selective attention, visual search, target, distractor, feature search, serial search, guided search, conjunction search, feature integration theory, preattentive stage, binding problem, illusory conjunction, attentional blink, rapid serial visual presentation, repetition blindness, fusiform face area, parahippocampal place area, response enhancement, sharper tuning, change blindness
I enjoyed reading and gaining knowledge about topic of attention.It is one of my favorite topic so far. For instance, it is interesting that some people can concentrate on couple things at the same time, or that they can focus on studying while the music is playing or the TV i on. And some people need complete silence that nothing and no one will not distract them.
Two things that I found the most interesting in this chapter is the selection of space, so what we actually called "pay attention" and the disorders of visual attention.
What does paying attention actually mean? According to the textbook it is the process whereby a person concentrates on some features of the environment to the (relative) exclusion of others. There are couple experiments that the authors includes. In vision, it is possible to direct attention to one location or one object. If something happens at an attended location, we will be faster to respond to it. It is the spotlight of attention where actually the attention is not moving from point to point, the physical spotlight would move.
Disorder of visual attention- the most common is the attentional equivalent of a visual field defect. Also, neglect patients are not able to describe objects,, or ignore some objects. Neglect is the inability to attend or respond to stimuli in the contralesional visual field. Another inability to perceive a stimulus to one side of the point of flixation in the present of another stimulus is called extinction.
The least interesting things were the physiological basis of attention, yet important to understand the topic better.
I would like to talk in class more about the change blindness and picture memory.
terms:
selection of space, spotlight of attention, neglect, equivalent of a visual field defect,extinction.
Two things from chapter eight that I found interesting are illusory conjunction and attentional blink. Illusory conjunction is a “false combination of features from two or more different objects”. This happens when you don’t look at something long enough to gather information about all the features of each object. The reason this happens is because our brain is trying to make the most out of the information it has received. I think this is interesting because although our brain technically made an error, this concept is yet another example of how powerful our brain is and how much it affects our perception of things.
The other concept I think is interesting is attentional blink. An attentional blink occurs when viewing something in a stream; for example, letters. If a stream of letters is being presented and the individual is supposed to report an X and a white letter. Depending on which variable is presented first determines what the individual reports. If X is first, they’ll report X but not the white letter. The individual seems to “miss” the white letter because it appeared 200-500 milliseconds after the X. It seems that our visual system can’t pick up the second target because its attention was to the first target and didn’t have enough time to get ready to pick up the second target. I think this is interesting because it’s surprising that our eye “blacks out” for a couple hundred milliseconds.
As usual, I found the physiology of the eye to be uninteresting. Although I know that this information is very important how why our visual system works the way it does, I’m more interested in what happens because of those structures. I did, however, find the fusiform face area (area in the striate cortex that “sees” faces) and parahippocampal place area (area in the cortex that “sees” places) very interesting.
I didn’t feel that there was much information in this chapter to help understand the history of psychology but I did find one concept. It’s the feature integration theory created by Anne Treisman. The feature integration theory says that a limited set of basic features can be processed at the same time without selective attention but that other, more complicated, properties require attention.
Some topics I’d like to discuss more in class are sharper tuning and the binding problem.
Terms: sharper tuning, binding problem, feature integration theory, selective attention, fusiform face area, parahippocampal place area, striate cortex, attentional blink, illusory conjunction, perception
Chapter 8 begins by explaining that attention is not a single thing, but rather a process that refers to several different systems working together. Overt, Covert, divided, sustained, and SELECTIVE attention are all different ways of focusing on something. All of these kinds of attention assume that there are universal rules to our systems of paying attention. Most of chapter 8 focuses on the way we isolate and measure attention. REACTION TIME is the time from the onset of the stimulus to a response. A CUE is a stimulus that might indicate where or what a subsequent stimulus will be. STIMULUS ONSET ASYNCHRONY is the time between the onset of one stimulus and the onset of another. All of these terms are used to describe how one focuses on something. The author uses the analogy of a camera A: either moving from one area to another to take a photo or B: widening the lens to focus on a larger field as apposed to zooming in on a small area.
This visual field is studied by finding the relationship between TARGET ITEMS and their surrounding DISTRACTOR ITEMS.
I found it interesting that the book explains FEATURE SEARCHES by relating them to the 'Where's Waldo' children's books. Humans are apparently very good at finding one specific item by identifying it's unique aspect to it's surrounding stimulus. Red and white stripes are very noticeable (unless Waldo is in a Candy Cane factory).
This is possible because we have different types of searches that are more efficient than others in certain situations. FEATURE SEARCH=Single attribute. SERIAL SELF-TERMINATING SEARCH=item by item. GUIDED SEARCH=restriction to one set of basic information about the target CONJUNCTION SEARCH=search for the presence of 2 or more attributes.
We know that we can perform these searches very quickly thanks to RAPID SERIAL VISUAL PRESENTATION (RSVP) studies in which streams of information appear rapidly. Targets are distinguishible if they appear 200-500 milliseconds before the second stimulus is presented. These studies also showed that while our eyes move, even if they are wide open, we are effectively blind. This is called the ATTENTIONAL BLINK.
The subject matter that I would like to be further discussed is the Parietal lobe and the higher processing of the visual system.
The first topic that was interesting was the first topic in the book, attention. Attention is described as any of the large set of selective processes in the brain. In order to deal with not being able to handle all inputs at one time, the nervous system has certain adapted mechanisms that are able to restrict processing to a sub set of things, places, ideas, or moments. There are many different types of attention. Overt attention refers to directing a sense organ at a stimulus. For example, fixating your eyes on a certain word. Covert attention, however, is like when you are pointing your eyes at the words in the book but really you are directing your attention to the person beside you. There is also divided and sustained attention. Divided attention would be like when you are reading a book while listening to the television. Sustained attention, however, is when you are fully focused on something. Selective attention is the form of attention that is involved when processing is restricted to a subset of the possible stimuli. In other words, it's the ability to pick one (or a few things) out of many stimuli.
The next topic I thought was interesting was visual search. Visual search is looking for a target in a display containing distracting elements. (Target is the goal of a visual search). Distractor items are any stimulus that is not the target. A good example of this is "Where's Waldo." It could even be something simple such as looking for the cold water handle on a sink. There are different types of these searches. A feature search is the search for a target defined by a single attribute, such as a salient color or orientation. (This means that it stands out visually from the others). We can process the color of all the items at once (parallel). When we measure this RT (reaction time, or a measure of the time from the onset of a stimulus to a response), it doesn't change with the set size. A serial self-terminating search is a search from one item after another, that ends when a target is found.There are also guided searches and conjunction searches. A guided search is a search where attention can be restricted to a subset of possible items on the basis of information about the target item's basic features. For example, if you are looking for a tomato in a lot of red items you would be able to find it easily because of its different features. Lastly, a conjunction search is a search for a target defined by the presence of two or more attributes. For example, you may look for a red vertical target among red horizontal and blue vertical distractors.
There were a few topics that weren't so interesting to me. One of the topics was attending in time. Rapid serial visual presentation is an experimental procedure in which stimuli appear in a stream at one location at a rapid rate. For example if you're trying to decide if there's an X in a stream of letters, we can accurately pick out an X if the letters are appearing at a rate of 8 to 10 items per second. Attentional blink is the difficulty in perceiving and responding to the second of two target stimuli among 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. These were hard for me to understand and I found them fairly uninteresting. I'd like to learn more about the top two topics because I think they'd be the most interesting and helpful to learn about.
Terms: attention, selective attention,reaction time (RT), visual search, target, distractor, feature search, salience, parallel, serial self-terminating search, guided search, conjunction search, rapid serial visual presentation, attentional blink.
It would be impossible to handle all of the stimuli the brain receives at once so the nervous system uses attention (restricts processing to a subset of these items at one time). Visual search experiments are interesting because the participants look at a target(the goal or focus of visual search) in a display containing distractor items (stimuli other than the target). These experiments are interesting because they look at a phenomena that occurs quite frequently in the real world. The set size of a display is the number of items in a display, when this increases it becomes more difficult to focus on a target. Experimenters often measure the reaction time or the amount of time for the subject to respond and say that they see the target in the display. A simple feature search is a search in which the individuals are looking for a target with a single definable feature. Interestingly, the authors said that if this unique feature of the target is salient (stands out visually from the distractors) then the actual number of distractors does not matter much. This is evidence that we can process simple feature search in parallel (processing multiple stimuli simultaneously). I found it interesting that not all types of search are as efficient (faster reaction time). For example, serial self-terminating search (where individual stimuli are examined serially) is less efficient because individual items need to be looked at before the person can differentiate the target and the distractors. Although these studies of attention were interesting, it is helpful to my learning to think about them in terms of the real world searches that they gave examples of. The authors explained that in many real life searchers individuals use what is called a guided search which is when the individual narrows down the amount of distractors by using a basic feature of the target they were looking for. This really made sense to me, especially when they used the example of the vegetables at the grocery store. When I am looking for a particular vegetable I am not going to use a serial self-terminating search and look at each individual vegetable until I find my target, I will instead use a guided search so I am not in the grocery store all day! I thought the author made a great point that our visual searches are often much more complex in the real world than they are in a laboratory setting. As in most research the goal is to mimic the real world but keep it controlled enough to study the phenomena. Researchers try to make more complex conjunctional searches where the target is defined by multiple attributes instead of one simple feature. I did not like the binding problem (which is the problem of putting different attributes together in which different parts of the brain are responsible for) because it seemed a little abstract. However, it makes more sense when you incorporate the feature integration theory which says that some basic features can be processed in parallel but in order to correct for the binding problem more attention must be given to the display. I found it very interesting that we often have a greater attentional selection to particular stimuli. I found the fusiform face area (in the fusiform gyrus of the extrastriate cortex with preference to faces) to be particularly interesting. I kind of noticed this phenomenon when I was presenting at conferences and students had photos on their poster with faces. I found that I was drawn to the faces in their posters and the poster with a face was more likely to catch my attention. I also found change blindness (failure to notice change between scenes if change doesn’t change the sequence meaning) to be interesting but I did not like the pictures because they reminded me of those touch screen games with the pictures that I am horrible at. Finally, I think it would be helpful to talk more about the physiology of attention in order to build on the phenomena in the book. Also, it would be nice to talk more about disorders of attention such as visual-field defect (portion of visual field with abnormal vision do to damage) or neglect (inability to respond to items in the field opposite to damage).
One topic that I found interesting was visual search. Visual search is looking for a target in a display containing distracting elements. In a typical visual search a person looks for a target or the goal of the visual search, but there are often distracter items, or anything other than the target. Sometimes these visual searches can be quite easy, like looking for a jar of peanut butter in the cupboard. However, these searches are not always easy, and we are sometimes distracted, such as finding waldo in where is waldo. This leads to another topic that I found interesting efficient and inefficient visual searches. Visual searches are often efficient when a feature search is used; a feature search is a search for a target defined by a single attribute. When these items are salient they stand out visually from the neighbors and the target seems to pop out. When looking for the object we process in parallel or we process multiple stimuli at the same time. When searches are inefficient it is generally because the features are time similar for us to differentiate between the two. This generally leads to a serial self terminating search; a serial self terminating search is a search from item to item ending when a target is found. As you can see this method is not at efficient at immediately knowing the target. One topic that I didn’t find very interesting was local and global approaches to scene recognition. I did not enjoy this topic very much because I found it fairly difficult to understand. Another topic that I did not enjoy very much was what do we actually see. I did not enjoy this topic because I felt their was not very much information that accompanied it. One topic that I would like to go over in class is the physiological basis of attention. I found this topic interesting but found it a little difficult to understand. Another topic I would like to go over is selection is space.
Terms
Visual Search
Target
Distracter
Feature search
Salience
Parallel
Serial self-terminating search
Some additional information for visual search, When looking at attention we have to ask what attention is. Attention is any of the very large set of selective processes in the brain. To deal with the impossibility of handling all inputs at once, the nervous system has evolved mechanisms that are able to restrict processing to a subset of things, places, ideas, or moments in time. There are different types of attention, overt attention, covert attention, divided attention, sustained attention and selective attention are some examples. Selective attention is the ability to pick one or a few out of many stimuli. When looking for information on attention it is a good idea to look at visual search experiments which provide an approximation of the actions of attention in the real world. In an typical experiment a subject will have to pick out a target from a group of distracters.
I found chapter 8's topic of attention to be very interesting. Attention is any of the very large set of selective processes in the brain. To deal with the impossibility of handling all inputs at once, the nervous system has evolved mechanisms that are able to restrict processing to a subset of things or places or ideas or moments in time. I found it interesting to read about the various types of attention that the book discussed. Covert attention is when you direct attention at something other than what you are fixated on, an example being listening to music while reading a textbook. Overt attention is when you direct a sense organ at a stimulus. Another type of attention is divided attention. Divided attention is when you equally split your attention between two different stimuli. Sustained attention is keeping your attention on the same stimuli for a period of time. The type of attention that is most commonly discussed in chapter 8 however is selective attention which occurs when processing is restricted to a subset of the outside stimuli.
One of the topics that I found the most interesting in this chapter is the topic of visual searches. A visual search is defined by the text as looking for a target in a display containing distracting elements. The target is the goal of the visual search, or whatever you are looking for. The tricky thing about visual searches is that there are always many distractors, which is any stimulus other than the target object. An easy example to remember of a visual search is a where's waldo puzzle. Waldo is the target object and all the other people in the picture are the distractors. A feature search, on the other hand is a search for a target defined by a single attribute, such as a salient color or orientation. For an object to be salient, it needs to stand out visually form neighboring features, and pop out). According to the text, when the target and distractors in a visual search task contain the same basic features, the search is inefficient (meaning that each additional distractor adds about 20 to 30ms to a successful search for a target and about twice that amount of time to search that ends without finding a target. One reason this happens is because these types of visual searches involve a serial self-terminating search. which is a search from item to time, ending when a target is found. On average, half of the items in the set will be searched before the target object is even found. Another explanation is the limited-capacity parallel process. This is a process that is capable of handling many stimuli at one time but that processes each item more slowly as the number of items increases. The idea is that we can process all the items in each of the right-handed displays at once (from figure in text) at once but that as the number of items increase, processing resources must be spread more thinly. Another type of visual search is the conjunction search. This is a search for a target defined by the presence of two or more attributes. An example of this would be looking for something that is red and vertical, when the distractors are green and horizontal. Anne Treisman put together a model for the visual search with is known as the feature integration theory. Which holds that a limited set of basic features can be processed in parallel preattentively, but that other properties, including the correct binding of features to objects, require attention. There are two stages to this model, the first is preattentive which referrers to the processing of a stimulus that occurs before selective attention is deployed to that stimulus. Sometimes there is a binging problem. This is the challenge of tying different attributes of visual stimuli which are handled by different brain circuits, to the appropriate object so that we perceive a unified object. Another Model of visual search is guided search theory. This model holds that early visual processes can guide the subsequent deployment of attention.
Another topic that I found interesting in this chapter is the disorders of visual attention. The most common problems that occur are neglect and extinction. These occur when there is a parietal lobe (a lobe of each cerebral hemisphere, that lies toward the top of the brain between the frontal and occipital lobes) lesion. Neglect is the inability to attend to or respond to stimuli in the contralesional visual field (typically, neglect of the left field after right parietal damage). Also, neglect of half of the body or half of an object. Extinction is somewhat related to neglect. it is the inability to perceive a stimulus in the presence of another stimulus, typically in a comparable position in the other visual field.
One topic that I found the least interesting is the topic of RSVP. RSVP stands for rapid serial visual presentation, defined by the book as an experimental procedure in which a stream of stimuli appear at one location(typically fixation) at a rapid rate(typically about eight per second). An example is to image the situation of looking at a stream of letters that all appear at the same locaiton in space and trying to decide if there is a number in the stream of letters or other similar tasks. It gets even trickier if a second characteristic is added to the mix. 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 to 500 ms before the second stimulus is presented.
Another topic that I found the least interesting in this chapter is the section of the chapter that covered the physiological basis of attention. All of got out of this section was that attention could enhance neural activity, attention could enhance the processing of a specific type of stimulus. I also learned that the fusiform fac area is an area in the fusiform gyrus of human extrastraite cortex that responds prefecntially to faces in fMRI studies. And that parahippocampal place area is a region of cortex in the temporal lobe of humans that appears to respond with particular strength to images of places. Even though it is very rare, sometimes people will be unfortunate enough to experience bilateral lesions of the parietal lobes. There are three main symptoms of this (known as Balint syndrome). the first is that the spatial localization abilities of patients with balint syndrome are greatly reduced. as a result, a patient may have a very hard time trying to reach to an object. The second is that patients with this dont move their eyes very much. and finally, they behave as if they can see only one object at a time. this seems to be like an extreme form of extinction or neglect, in the attending to one object eliminates everything else. this inability to perceive more than one thing at a time is known as simulagnosia.
Topics that I would like to cover more in depth in class are picture memory and change blindness. Changes blindness is the failure to notice a change between two scenes. if the changes does not alter the fist or meaning of the scene quite large changes can pass unnoticed. the book discusses several different experiments that were done researching peoples picture memories. I found this very interesting and would like to discuss them in greater detail in class.
Terms: Attention, covert attention, overt attention, divided attention, sustained attention, selective attention, visual search, target, distractor, feature search, salient, serial self-terminating search, limited-capacity parallel process, conjunction search, feature integration theory, preattentive, binging problem, guided search theory, rapid serial visual presentation, attentional blink, fusiform face area, parahippocampal place area, neglect, extinction, balint syndrome, simlagnosia, change blindness
The book states that attention is not a single thing, it is a label we give to a group of mechanism within our nervous system that allow us to deal with all the inputs we get from the outside world.
When we have an encounter a stimulus, there is a certain amount of time between the point when it is presented and when we reaction to it. Scanning for an open seat (the goal stimulus or target) in the union can be hard during the lunch hour. There are many other stimuli or distracters (other tables). However there can be cue leading us to that empty seat, like people moving away from the area. The book describes “stimulus onset asynchrony” as the reaction time between the onset of one stimulus and the onset of another, or the onset of the cue and the stimulus (in this case the people walking away and the spotting of the open seats).
The book also introduces the different theories of how we conduct our searches and scans with our eyes. Similar to saccadic, do we search with spotlights? Do our eye dart as they sweep across the scene? Although this seems logical to me, the book points out other ways too. Attention might expand from our set fixation, and then fading to focus on another stimulate.
The book states that there are different ways that we search for in regards to our target. Feature searches-looking for one certain feature- are the most efficient. Salient means that the target’s features stands from the distracters with distinguishable features like color and orientation. We can scan and process these searches same time or in a parallel process.
There are searches that are inefficient or more complex. The distracters are similar (contain the same basic features) to the target. Each stimulus has to be examined individually until the target is spotted. This is called serial self-terminating search. Another inefficient search our visual system conducts is called limited-capacity parallel process. This expansion on the parallel process is similar but takes longer. Our processing resources are spread thin on these similar stimuli, and we have to spend more time on each of the stimulus.
The book states that either an inefficient or efficient process is a holistic view. There are also processes like conjunction searches. In these searches, the target is more likely defined by the presence of two or more attributes(Like if you are looking for a table in the union, you want it to me empty and a certain size). Thus searching and scanning is more of a procedure.
Anne Treisman proposed feature integration theory a model for the process of scanning and processing of target. Within this model there are two stages. The simple and limited set of basic features can be processed in parallel searches within the preattentive state (You might pick up any open table). However you really need a big open table. The binding problem is the challenge of tying all the different attributes together. This can be a “problem” because it is easy to make mistakes, or combined features that are wrong because they are handled by different brain circuits. This is called illusory conjunction. The second stage, or the attentive stage is the process of attention to a stimulus or location, and the search can stop
The book also discusses the physiological basis of attention. When you are asked to paid attention to a location on your visual field, the neurons in part of our brain that respond to that part of the field will become more activated. There are parts of the brain that are attentive to faces( fusiform face area).
Lastly the book discusses disorders of the visual attention system. First of all in damage to the parietal lobe; patients will lose or neglect a part of their visual field. The patient will no longer have the ability to attend to or respond to stimuli in the “contralesional visual field”. Balint syndrome happens when patients have lesions in both right and left hemisphere partial lobes. This affects normal scanning in a couple of different ways. The patients can only really see one object at a time, the rest blend together, this is called simultagnosia. The book questions that even if a patient cannot understand more than one object, do they still perceive it in their vision. Furthermore, how much do people without visual-field defect really understand about what they see? The book uses the popular example of the video with the ape man. I remember being amazed that I missed something right in front of my face. I think this phenomenon shows how we scan pictures or scenes. We did’t lose or fade our attention (covertly or overtly) from our target to a distracter. Maybe it is because the distracter is not similar to the target. Either way we can see heuristic. That our brain sees what it what to see, and leaves out other details.
What I’d like to focus on in class is the physiology basis of attention
target, distracters, stimulus onset asynchrony reaction time self-terminating paralell salient inefficient efficient, binding problem guided search theory fusiform face area balint sydrome simlagnosis feature search limited capacity parallel process conjunction search preattentive attentive
Chapter 8 talks about attentions and scene perception. This chapter was a fairly interesting one. First, I will start off by defining attention, it is a word we often hear but do not think about. Attention is directly tied to the brain by any large selective process. The book goes on to talk about what it means “to pay attention”. This is also something we often hear but do not think about. I thought it was very interesting that the book defined reaction time as the measure of interest. The actual definition is the amount of time a probe appears and when that probe hits a response. A cue is very important when talking about reaction time. A cue is a stimulus that indicates where a stimulus will be. Moreover, the book talks about stimulus onset asynchrony (SOA). I found the spotlight metaphor used in the book to be very interesting. The spotlight metaphor talks about attention and the way it moves from one fixation point to a cue. Visual search, target, distracter, and set size are all key terms in attention and how it works. It is important to note that all four of these terms are research terms therefore they are used in research. First, visual search means that a person is looking for a target is a display which contains distracting elements. Second, a target (what the person is looking for) is the goal of the visual search. Third, a distractor is any stimulus other than the target. Last, the set size is the number of items in a visual display. It is really neat to see all these work together and play a key role on the entire test. The chapter goes on to talk about tests and different things that are studied when studying attention. One that I found very basic is serial self-terminating search. We have all seen things like this. This is a search that ends when the target is found. I thought the section titled “Most Real-World Searched Are Neither Totally Efficient nor Totally Inefficient” was interesting. Real World searched are a conjunction search. This is when you search for a target that has two or more distinct attributes. The example given in the book (also seen in class) is the example of a picture of a parking lot that asks us to find a red station wagon. I found illusory conjunction to be very interesting also. We also did this in class. Illusory conjunction is a false combination of the features from two or more different objects. Next, attentive is when attention is directed to one item at a time. Illusory conjunction and attentive are two parts to Anne Treisman’s feature integration theory.
Next, the book talks about Attending in time: This is switching from attention in space to attention in time. Psychologist use rapid serial visual presentation (RSVP) as a means of studying attention in time.
The book then goes on to talk about the physiological basis of attention. Another thing we don’t think about is how attention could enhance neural activity. This should not be surprising considering attention is tied directly to the brain. It gets more interesting as the book goes on to talk about how attention could enhance the processing of a specific type of stimulus. Two terms that are associated with this are fusifrom face area and parahippocampal place area. The book goes even more in depth to talk about how attention affects single cells. When our attention is focused on one stimuli, neurons are released, this is called response enhancement. If a neuron response more precisely than normal, this is called sharper turning.
There are also some disorders of visual attention. One disorder is visual-field defect. Another disorder is parietal lobe. First, visual-field defect is a portion of the visual field with no vision or with abnormal vision. This is typically due to damage to the visual nervous system. I thought the section that talked about neglect was very interesting. The book talks about how neglect patiants act as if part of the work were not there. Extinction is related to neglect. Some people think extinction is neglect in a milder form. Extinction as defined by the book is the inability to perceive a stimulus in the presence of another stimulus.
This chapter made me really ask questions about eye witnesses in the courtroom. This chapter really exposed to me how unreliable eye witnesses are. This is what I found most interesting.
Attention is a collection of encoding process, cue detectors, and effortful control. When we are trying to perform a task we divert most of our cognitive energy to trying to complete the task. For example visual search tasks force us to look at the item set and contemplate, pretty much overpowering other cognitive processes and perception of stimuli that are not related to the task. Feature search refers to our ability to scan an entire group of objects and compare them almost instantly, based on a parallel feature; a feature that most or all of the objects share, such as color or orientation. Feature search allows our brain to pick out contrasting items and pinpoint them very quickly. This is a limited-capacity parallel process, meaning that as number of items and number of features being encoded increases our perceptual processes are more and more unable to analyze features of all the objects and may have to switch to a method called self-terminating serial search, which basically means examine each item one at a time until the target is found. Most searches are probably a combination of parallel feature searches and less efficient serial searching. I believe our brain will try to do the least effortful, and fastest way method first. Then we will either give up or if we feel properly motivated we will continue to search and may begin to search each item individually or perhaps a few items at a time. Feature integration theory describes it as our brain using a feature search, and then when it recognizes the possible target based on features it examines the target and looks for confirmation that it is indeed what we were looking for. This is called a binding process.
Our brain has limited ability to encode, and especially recall feature information. Generally these processes are influenced by expectations and the brain is already putting cognitive effort into looking for a specific feature. Illusory conjuntions are errors in recall in which we combine two features that were present but not present together.
Attentional blink is an interesting phenomena, it happens in a range of 200-300 milliseconds after a particular target has been percieved, if another target is presented the viewer is likely to miss it. It is possible that the viewer is in the second stage of feature integration, confirming that the first target is indeed legitimate. It is interesting that it has a very specific temporal range.
Feature search, parallel features, limited-capacity parallel process, self-terminating serial search, Feature integration, binding process, illusory conjunction
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