Karteikarten
Visual Attention
Karten in diesem Stapel (51)
- 1What is attention?Attention describes the way in which sensory inputs are selectively prioritised for high-acuity processing, because the brain has a limited capacity.
Any definition of attention must refer to this issue. - 2What is overt attention?This is attention characterised by the fovea being oriented toward the relevant visual input. This allows high-acuity processing, as a result of cortical magnification. This is done through saccades and fixations.
- 3What are saccades?These are the quick, ballistic (i.e. direction can’t be changed midway) movements of the eye. We do about three pers second, and they occur within tens of milliseconds, which is too quick for any processing to occur.
- 4What are fixations?This is when the eye stops moving. This is when processing of visual input can occur.
- 5What determines where the person fixates?Low level cues include salience, such as the objects colour, or motion (particularly in the direction of the eye).
Higher level cues include the nature of the task, and prior knowledge about a scene or situation. - 6What is covert attention?This mechanism describes the way attention and eye movements can be dissociated. For example, you can be looking somewhere, but pay attention to an area in the periphery.
- 7What is divided attention?This is when multiple things are being attended simultaneously. This minimises the resources available to each task.
- 8What is sustained attention?This is keeping attention on one object for a long time
- 9What is selective attention?This is the ability to pick up one (or a few) thing to focus on, among many stimuli.
- 10What is the Posner cueing (or precueing) paradigm?A person fixates on a fixation cross, and needs to indicate on what side a stimulus (E.g. red circle) appears. There is a cue (e.g. an arrow) which indicates where the stimulus is likely to appear. This cues that side, making processing of the stimulus quicker, if the cue is valid. The cue needs to be valid most of the time, or the effect disappears.
- 11In what way can attention alter the appearance of a stimulus? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INCOMPLETE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ GO BACK IN TEXTBOOK AND READ THIS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~In a cueing paradigm, participants were asked to indicate which grating (on the right or the left) had a greater contrast. When one side is cued (e.g. a dot appears somewhere off to the side), the participant is more sensitive to the level of contrast of that grating, and they are less likely to see it as having the same contrast as the other grating (i.e. a smaller difference in contrast will lead to the participant as seeing the gratings as being the same).
- 12What is feature search?This describes a visual search task wherein the target has only one significant feature difference from the distractors (E.g. colour). The number of distractors has no influence over reaction time. This is known as the pop-out effect. Attention is not needed for this task. For this reason, it's also called pre-attentive or parallel search.
- 13What is conjunction search?This is where multiple features of the target differ from certain distractors (e.g. there is variance in colour and orientation). Here, the number of distractors does cause a linear increase in the reaction time. Attention is required for this task. This uses serial search of each object, which ends when there are no more objects to scan, or the target is found.
This search is difficult and slower - 14What is feature integration theory?This describes the binding of features during conjunction search. There are two phases:
Preattentive stage: this is the independent processing of different features of an object in different parts of the brain, early in the perceptual process, before we're aware of the object. Because this process doesn't require attention, it is automatic and effortless.
Focused attention stage: upon paying attention to an object, the features are bound together, and we become aware of an object and all of its properties. - 15What is the binding problem?This describes the fact that, during conjunction search, you need to merge features together into a single object when observing an object. The way the brain does this is described by feature integration theory.
- 16What are illusory conjunctions?This is the incorrect binding of features observed when a person briefly observes shapes with different features. E.g. may have seen a blue X and a red O, but may report a red X.
- 17What is inattentional blindness? What evidence shows its influence?This is a participant's failure to notice a fully visible - but unexpected - object, because attention is preoccupied.
In an experiment, participants look at fixation cross where perpendicular lines appear, and need to indicate whether the horizontal or vertical line is longer. On the last trial, a small square appeared. Only 2 participants reported seeing it.
Participants watched game of people passing a ball around, and either a woman with an umbrella, or person in gorilla suit, walked through game. 46% of pps were unaware of this.
In a study, 24 radiologists were shown scans of lungs and and searched for cancerous nodules. In the last scan, a gorilla 48 times the size of the average nodule, was present. 83% did not report seeing it, despite the majority looking directly at it. - 18What is change blindness?This is the failure to detect changes in a scene, which is easily seen once it's noticed.
This has been shown in the Rensink paradigm, where the different images flash with a brief blank period in between. People are very bad at detecting the difference, and must see it multiple times. However, once the correct part of the screen is cued, the difference is detected more easily. - 19What is neglect?Visuo-spatial neglect leads a patient to act as if half of the world weren't there, as a result of damage to the parietal lobes. When drawing a picture (e.g. house, clock, flower), the person lacks crucial detail on the neglected side (e.g. drawing a circle, but not writing the numbers on the right side of the clock).
- 20What is extinction?This is the inability to perceive a stimulus on one visual field, while a stimulus in the other field is present.
For example, a patient can identify a spoon on one side and a fork on the other, but when both are presented at the same time, can only report one. - 21What is attentional capture?This is the way in which particularly salient objects attract our attention, perhaps without our meaning to.
- 22What is a saliency map?This is a map of an image which shows more salient regions in a lighter colour.
- 23Upon first looking at an image, what determines what we look at first? How does this change over time?Upon first glance, our eyes are directed to the most salient parts of an image. After a few moments, our gaze is directed by cognitive processes, taking into account our knowledge, intentions, interests, and expectations.
- 24What are scene schemas? What evidence suggests their influence?Scene schemas describe what we expect to see within a particular scene.
Objects which are out of place according to the scene schema receive longer fixations (e.g. a printer in a kitchen).
People use scene schemas to determine when to look for important stimuli. For example, in an experiment utilising a driving simulator, the participant was more likely to notice a stop sign if it was located at an intersection than in the middle of the block. This is because the participant's knowledge of regularities within the environment lead them to look for stop signs in places they're used to seeing them. - 25How does a person's goals influence eye movements?There is a very clear influence of goals on eye movements. While observing a painting, participants' eye movements concentrated on objects they were asked to remember. It was also possible to decode, in another experiment, what specific object a participant was searching for in an image through their eye movements.
- 26What is the influence of task-related knowledge on eye movements?Because eye movements allow us to interact with our environment by gaining information about it and act accordingly, our eye movements are closely related to the information available while we're doing a task. As we act, the environment changes, and the aspects of the environment that we're interacting with will shift, causing shifts in attention, as marked by eye movements. Eye movements precede motor movements by a fraction of a second.
- 27What is the 'just in time' strategy?This describes the way that, as we act, we move our eyes just before we need the information that this movement gives us. Eye movements precede motor movements by a fraction of a second.
- 28What is spatial attention?This refers to attention directed to a particular location.
- 29What is the same-object advantage? What evidence supports its influence?This is the idea that when attention is focused on a location, the entire object at that location receives attentional processing.
In an experiment, there are two rectangles, one on either side of a fixation point. A cue, followed by a stimulus, may appear at either the top or bottom of each rectangle (all of these points are equal distance apart). The participant indicated when the stimulus appeared. When the cue matched the location of the stimulus, response times were quickest. However, if the cue occurred in the same rectangle as the stimulus, reaction times were still faster.
In another study, participants looked at a photographed scene. After 3 seconds, the cue stimulus appeared. 317 ms after its appearance, a target stimulus appeared, either on the same object or a different object to the cue stimulus. The participant is told to look at the target stimulus as soon as it appears, and indicate what letter is transcribed on it. Response times were quicker when the cue and target stimuli appeared on the same object. - 30What evidence suggests that attention can affect the way an object is perceived?In an experiment, participants watch fixation cross. One side is cued with a dot, then two gratings appear, and they determine which of these has the highest contrast. If the gratings have different contrast, the cue has no effect; but if the gratings are identical, the cued side is indicated as having the greater contrast.
Other research has found that attended objects are perceived as bigger, faster, and more richly coloured. - 31What evidence shows the way that focusing on particular objects affects neural firing?In an experiment, participants were presented with (to both eyes) both a superimposed image of a face and house, one of which was moving. They were asked either to focus on the face or the house, or to indicate the direction of movement.
Focusing on the face increased activation in the fusiform face area (FFA). Focusing on the house increased activation in the parahippocampal place area (PPA). Focusing on the movement increased activation in the middle temporal/medial superior temporal (MT/MST) area. - 32What evidence shows the way focusing on a particular location affects neural firing?Participants look at the center of a stimulus disk, which consists of different sections, made up of lines of different colors and orientations. Depending on where the participant paid covert attention, the activity in the visual cortex was altered. This effect was depicted in attention maps, which could be used to decode where the participant was paying attention according to the activity in the visual cortex.
- 33What is coherence?This is the degree to which the responses of two brain areas are synchronised.
- 34What is a local field potential (LFP)?This is a measure of the general response of thousands of neurons surrounding an electrode.
- 35What evidence shows the way attention can cause the increased coherence of two brain areas?Generally, locations labeled A and B, within V1 in the visual cortex, send signals to location C, in the temporal cortex. In an experiment, a monkey pays attention to a fixation point. Two stimuli appear on the screen.
Paying attention to one stimulus causes the increase coherence between the LFP responses in locations A and C. Similarly, paying attention to the other stimulus causes increased coherence between the LPF responses in locations B and C.
It should be noted that paying attention to either stimulus did not significantly affect the responses given off at locations A or B, as attention doesn't appear to affect V1.
Thus, attention can cause the increased communication through coherence between different areas. This process also happens during higher functioning along the visual system. - 36What evidence supports feature integration theory?In an experiment, participants were briefly presented with a set of four shapes of different colours and sizes, with a black number on either side of the display. They were instructed in advance to report all of these stimuli, causing the division of attention. Because they were less able to attend to each object, the features were sometimes bound incorrectly, leading to illusory conjunctions, as predicted by feature integration theory.
In the case study of RM, the patient suffered from Balint's sydrome, and was unable to focus or shift his attention when presented with multiple objects. As such, when he was presented with two stimuli, he made illusory conjunction errors on 23% of trials, as he wasn't able to attend them. - 37What evidence shows the influence of top-down processing within feature integration theory?In an experiment, participants showed illusory conjunctions when reporting different shapes that were briefly presented. However, if the participants were told to look for real-world objects that were similar to the shapes, illusory conjunctions were less likely to occur. Knowledge of real-world objects increased their ability to correctly combine features.
- 38Under what circumstances are people less susceptible to change blindness? What evidence supports this?When the changes are surprising, or occur regarding objects that are meaningful to the person, or occur in task-related objects, people are more likely to notice them.
For example, smokers are more likely to notice changes in smoking-related objects (e.g. lighters) than in other household objects.
People are more likely to notice changes to objects which are unexpected in the context than to expected items (e.g. a printer in a kitchen).
During a colour-sorting task regarding blocks, participants are more likely to notice changes to the blocks' colour (task-related features) than to the block's height (task-unrelated features). - 39There is debate regarding whether the perception of scenes requires attention. What evidence supports the idea that attention is NOT required?In an experiment, participants were presented with a sequence of letters, which were either all identical, or one was different. The central task was to determine which was the case. The peripheral task regarded a stimulus which immediately flashed after the letter sequence, which was either a disk (half red, and half green) or a scene. The peripheral task was to determine either the order of the colours, or whether the scene included an animal.
Accuracy in the peripheral task was 90% when the stimulus was a scene, and only 50% (chance level) when it was a disk. This suggests that the perception of scenes doesn't require attention. - 40There is debate regarding whether the perception of scenes requires attention. What evidence supports the idea that attention IS required?In another experiment, a sequence of letters and numbers were flashed. The central task was to determine how many numbers were present. During this task, a natural scene flashed in the periphery. The periphery task was to indicate whether a car or an animal was present.
In isolation, participants showed 89% accuracy on the perception task. This dropped to 63% (still above chance) when the central task was introduced.
This suggests that, for at least some aspects of scenes, attention is required. - 41What is the load theory of attention? What research supports this theory?This is the idea that hard tasks (high-load tasks) take up more of your perceptual capacity than easy tasks (low-load tasks). The more of your perceptual capacity is empty (i.e. the easier the tasks are), the more remaining capacity there is, which enables the influence of task-irrelevant stimuli.
In an experiment, participants looked at a circle of letters, and needed to indicate whether an L or N was present. In the low-load task, the distractor letters were the same; in the high-load task, they varied. Only response times during the low-load task was very influenced by the presence of task-irrelevant stimuli, such as the flashing of a cartoon dog.
This is supported by studies in inattentional blindness. When the task was difficult, fewer people noticed distracting items than when the task was easy. This is because of their unused perceptual capacity allowing for the distracting effect of task-irrelevant stimuli. - 42What statistics demonstrate the dangers of using phones while driving?In a study of extensive driving recordings, in the case of 80% of crashes and 67% of near crashes, the driver was distracted 3 seconds prior. Using a mobile device was also involved in 22% of near crashes.
In an experiment, participants used a driving simulator which required them to press brakes as quickly as possible upon seeing a red light. Participants required to simultaneously talk on phone missed twice as many red lights, and had an increased time taken to apply the brakes. This effect occurred regardless of whether hand-held or hands-free phones were used. THis shows that talking on phone yields fewer mental resources available for driving.
Truck drivers have been found to be 23 times more likely to cause a crash or near crash while texting. - 43Are hands-free activities activated through voice recognition safer to use while driving than phones?No. It has been found that voice-activated activities (e.g. making reservations, posting on social media, responding to texts/emails) are in fact more distracting that phones.
- 44What is perceptual completion?This is the ability to recognise that an occluded object continues past the border of the occluding object.
- 45How has the habituation procedure aided research in the development of perceptual completion?Infants are presented with a display showing rod, which moves behind a stationary block. They are then presented with two moving rods, and one moving rod - both of which may explain the previous stimulus. Infants which can achieve perceptual completion will have seen the previous stimulus as one rod. Thus, the novel stimulus is the display of two rods, which they then look longer at. Otherwise, the novel stimulus is the single rod, which they then look longer at.
- 46According to experiments, when do children achieve perceptual completion?Infants develop this ability around the age of 3, as demostrated through an experiment which found both infants who could and could not achieve perceptual completion. However, another study found infants able to do this at the age of 2. Newborns have been found to be unable to perform this.
- 47What is Balint's syndrome?This is an attentional deficit which results from bilateral lesions of the parietal lobes. As a result, the person has reduced spatial localisation ability, does not move their eyes much shows optic ataxia (inability to reach for the objects they see), simultanagnosia (behave as if only seeing one object at a time, an extreme form of extinction or neglect), and are unable to bind features.
- 48What is optic ataxia?The inability to reach for things a person can see. This is a symptom of Balint's syndrome.
- 49What is simultanagnosia?This is an extreme form of extinction or neglect, wherein the person acts as if only able to see one item at a time. This is a symptom of Balint's syndrome.
- 50What is the influence of attention on other senses?Attention can prioritise one sense over the other, including causing the increase of pain.
- 51What cross-modal work has been done in regards to attention?In a visual elevation experiment, a participant looked at a fixation point, and indicated whether a light appeared at the top or bottom of the display (ignoring whether it appeared to the right or left).
A sound also played from a speaker, either on the right or the left of the display. When the sound of the speaker was heard from the same side on which the light appeared, the participant was quicker to respond.
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- Perception Karteikarten am Visual Attention, erstellt von Jamie Otten am 13/03/2019.
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