Chapter 6 - Study Questions Flashcards
(19 cards)
1) What are the two main points that William James makes about attention? (Hint: What it is and what it does.) What are two reasons for paying attention to some things and ignoring others?
Attention is the process of focusing on specific objects while ignoring others.
According to William James, we focus on some things to the exclusion of others.
As you walk down the street, the things you pay attention to stand out more than many other things in the environment. The reason you are paying attention to those things is that they are important to you.
Also, the perceptual system has a limited capacity for processing information.
Thus, to prevent overloading the system and therefore not processing anything well, the visual system, in James’s words “ withdraws from somethings in order to deal more effectively with others”.
2) What does the demonstration that involved finding Justin Bieber’s face tell us about attention and scanning?
The demonstration about finding Justin Bieber shows that scanning is an important feature. And when you scan your image you are moving your attention from one place to another.
Scanning is one of the mechanisms for selecting certain things in the visual environment, looking from one place to another.
Each time you briefly pause on a face as you scan for a specific face or target, you make a fixation.
When you move your eye to observe another face you make saccadic eye movement – a rapid jerky movement from one fixation to the next.
3) What are fixations? Saccadic eye movements? Over attention? How is overt attention measured? What is covert attention?
Each time you briefly pause on a face as you scan for a specific face or target, you make a fixation. Fixation is putting your attention on a specific thing.
When you move your eye to observe another face you make saccadic eye movement – a rapid jerky movement from one fixation to the next.
Overt attention is open attention or clear attention to one specific thin you are looking at.
Attention that involves looking at the attended object
Covert attention is attention without looking.
4) Describe the following factors that determine where we look: stimulus factors, cognitive factors, and task demands. Describe the examples or experiments that illustrate each factor. (Be sure you understand the role of stimulus saliency, attentional capture, scene schemas and scene statistics.)
Stimulus salience refers to physical properties such as color, contrast, movement, and orientation that make a particular object or location conspicuous.
When attention due to stimulus salience causes an involuntary shift of attention, it is called attentional capture.
Scene schemas – an observer’s knowledge about what is contained in typical scenes.
Scene statistics – are the probability of various things occurring in a dynamic environment.
5) What is spatial attention? Describe Posner’s experiment on speeding response to locations. Be sure you understand precueing procedure, covert attention, and what Posner’s results demonstrated.
Spatial attention is attention to a specific location
Precueing – is directing a person’s attention to a location before a stimulus happens.
In Posner’s experiment, the reaction time was faster when the square appeared after a correct precueing
This made him conclude that information processing is more effective at the place where attention is directed.
6) Describe Egly’s and Moore’s experiments on speeding response to objects. What is the same-object advantage?
When the stimulus is on an object, a stimulus that is in a similar location on the object also receives attention.
The faster responding that occurs when enhancement spreads within an object is called same-object advantage.
7) Describe Carrasco’s experiment that showed an object’s appearance can be changed by attention. Why did Carrasco have subjects report the orientations of the gratings rather than the contrast of the gratings?
Carrasco didn’t report the contrast to reduce the chances the subjects might think they might be influenced by any expectation they might have that attention might enhance the grating’s perceived contrast.
When the two gratings were physically identical, the subjects were more likely to report the orientation of the one that was on the same side as the flashed cue. Thus, when the two gratings were the same, the one that received attention appear to have more contrast.
“attention makes an object clear and vivid.”
8) Describe O’Craven’s experiment that showed how attention to faces or houses affects responding of areas specialized to respond to faces or houses.
Attention to Objects increases the Response of Specific Areas in the Brain.
Subjects were asked to focus on one stimulus: house or face. When they focused on the face, there was activity in the FFA and when they focus on the house it caused enhanced activity in the PPA
Also attention to movement caused activity in the movement areas MT moving face and MST moving house
9) Describe Datta and DeYoe’s experiment on how attending to different locations activates the brain. What is an attention map? What was the point of the “secret place” experiment? Compare this experiment to the “mind reading” experiments described at the end of Chapter 5.
Attention to Locations Increases the Responses at Specific Locations in the Brain.
Subjects were asked to look at different locations in the picture.
The experimenters created “attention maps “that show how directing attention to a specific area of space activates a specific area of the brain.
The secret place experiment was to see if the experimenters could check where the subjects were focusing on based on their brain activity.
It is similar to the mind reading activity where the computer could find the similar picture. Except in this one it was a little bit easier to predict since the person was just looking at areas within a picture and the experimenters had data indicating which area was activated depending on where in the picture the subject was looking at.
10) Describe Womelsdorf’s experiment that demonstrated how receptive fields are affected by attention.
Womelsdorf showed that attention can cause slight shifts in a receptive field’s location on the retina.
He demonstrated this by recording from neurons in a monkey’s middle temporal (MT) cortex. An area in the temporal lobe responsible for processing information about motion.
Womelsdorf mapped the receptive fields of a neuron as the monkey shifted its attention to locations that correspond to different locations on the retina. This result means that attention is changing the organization of part of the visual system.
Receptive fields, it turns out, aren’t fixed in place but can move in response to where the monkey is attending. This concentrates neural processing power right at the place that is important to the monkey at that moment.
1) Describe the following two situations that illustrate how not attending can result in not perceiving: (1) inattentional blindness (2) change detection.
Inattentional blindness means that not attending can cause us to miss things even if we are looking directly at them.
Change detection : detecting changes between two scenes/images
Change blindness in the difficulty in detecting changes in scenes.
2) Describe Li’s experiment that shows that under certain conditions we can perceive qualities of things we are not attending. How does the situation in Li’s experiment differ from the situation in the change blindness experiments?
Perceiving scenes requires attention, but some aspects of scene perception may not require attention.
In the case of Li’s experiments, subjects were asked to focus on a central task and then to answer questions on the peripheral tasks. Subjects were asked to answer questions about a disc or a scene, and the scene was well perceived but the discs were not.
The difference between change blindness and this experiment, is that we can perceive the gist of a scene and thus perceive a scene exists even without looking directly at it, but we might not be able to notice subtle nuances/change in the scene ( change blindness).
3) Describe the study by Forster and Lavie that shows that the distracting effect of a task-irrelevant stimulus depends on the nature of the task.
Task-irrelevant stimuli => Stimuli that don’t provide information relevant to the task which we are involved are task-irrelevant stimuli.
** If the task is easy, then task-irrelevant stimuli have an effect on performance. However, If the task is hard, task- irrelevant stimuli have little or no effect on performance.
4) How is Forster and Lavie’s result explained by Lavie’s load of theory of attention? Be sure you understand the concepts of perceptual resources and perceptual load.
Load theory of attention involves two key concepts: perceptual capacity and perceptual load.
Perceptual capacity refers to the idea that a person has a certain capacity that can be used for carrying out perceptual tasks.
Perceptual load is the amount of a person’s perceptual capacity needed to carry out a particular perceptual task. Some tasks, especially easy, well-practiced ones, have low perceptual loads; these low-load tasks use up only a small amount of the person’s perceptual capacity. Other tasks, those that are difficult and perhaps not as well practiced, are high-load tasks and use more of a person’s perceptual capacity. Lavie proposes that the amount of perceptual capacity that remains as a person is carrying out a task determines how well the person can avoid being distracted by task-irrelevant stimuli.
5) How has load theory been applied to inattentional blindness experiments?
We can also apply Lavie’s load theory to the phenomenon of inattentional blindness we described earlier. Remember that when subjects had to decide which line in a display was longer, only 10 percent of the subjects were aware of the small square presented near the cross. In terms of load theory, the difficulty length estimation task is a high-load task that uses up most of a person’s perceptual capacity, so there are few resources left to detect the small unattended stimulus. However, when the task was turned into a low-load task by asking subject to indicate which of the cross-hair was green ( horizontal or vertical), then 55 percent of the subjects reported seeing the unattended object
6) What are the two stages in feature integration theory? What does feature integration theory propose about the role of attention in perception and binding?
Preattentive stage and Focuses attention stage.
Feature integration theory tackles the question of how we perceive individual features as part of the same object. In her theory, the first step in processing an image or an object is the preattentive stafe. In the preattentive stage, objects are analyzed into separate eatures. For example, the rolling red ball would be analyzed into the features color (red), shape (round), and movement (rolling to the right). Because each of these features is processed in a separate area of the brain, they exist independently of one another at this stage of processing.
These features are combined in the second stage, called the focuses attention stage. Once the features have been combined in this stage, we perceive the object.
Attention brings things to our awareness and can enhance our ability to perceive and to respond.
The function of attention is to help create binding, which is the process by which features – such as color, form, motion and location – are combined to create our perception of a coherent object.
7) What evidence links attention and binding? Describe evidence that involves both illusory conjunctions and conjunction search in normal subjects and patient with Balint’s syndrome.
Visual search is something we do anytime we look for an object mong a number of other objects, sych as looking for justin Bieber in a group of musicians or trying to find Waldo in a “ Where’s Waldo?” picture. A type of visual search called conjection search has been particularly useful in studying binding.
Conjunction searches are useful for studying binding because finding the target in a conjunction search involves scanning a display in order to focus attention at a specific location. To test the idea that attention to a location is required for a conjunction search a number of researchers have tested the Balint’s partient R.M. and have found that he cannot find the target when a conkinction search is required. This is what we would expect because of R.M’s difficulty in focusing attention. R.M. can, however, find targets when only a feature search is required. Because attention-at-a-location is not required for this kind of search. Feature integration theory therefore considers attention to be an essential component of the mechanism that creates our perception of objects from a number of different features.
8) Describe the results of experiments that measured a) eye movements in autistic and nonautistic observers while they watched a film; b) the response of the STS to “congruent” and “ incongruent” conditions. What can we conclude from these results?
Austism is a serious developmental disorder in which one of the major symptoms is the withdrawal of contact from other people. People with autism typically do not make eye contact with others and have difficulty telling what emotions others are experiencing in social situations.
The nonauthistic observers fixated on the male actor’s eyes in order to access his emotional reaction, but the autistic observers looked near the female actor’s mouth or off to the side.
Another difference between how autistic and nonautistic observers direct their attention is related to the tendency of nonautistic people to direct their eyes to the place where a person is pointing.
The nonautistic person follows the poiting movement from the finger to the painting then looks at the actor’s face to await a reply. In contrast, the autistic observer looks elsewhere first, then back and forth between the pictures.
These results indicate that because of the way autistic people attend to events as they unfold in a social situation, they may perceive the environment differently than normal observers. Autistic people look more at thingsm whereas non-autistic observers look at other people’s actions and especialially at their faces.
Other experiments provide clues to physiological differences in attention between autistic and nonautsitic people. Kevin Pelphrey and coworkers (2005) measured brain activity in the superior temporal sulcus (STS), an area in the temporal lobe that has been shown to be sensitive to how other people direct their gaze in social situations. For example, the STS is strongly activated when a passerby makes eye contact with a person, but is more weakly activated if the passerby doesn’t make eye contact.
Pelphey measured STS activity as autistic and nonautistic people watched an animated character’s eye move 1 second after a flashing checkerboard appeared.
The character either looked at the checkerboard ( congruent condition) or in a direction away from the checkerboard ( incongruent condition). To determine whether the observers saw the eye movements, Pelphrey asked his observers to press a button when they saw the character’s eyes move. Both autistic and nonautistic obserrvers performed this task with 99 percent accuracy.
But even though both groups of observers saw the caracter’s eye’s move, there was a large difference between how the STS responded in the two groups. The STS of the non autistic observers was activated more for the incongruent situation but the STS of the autistic observers was activated equally in the congruent and incongruent situations.
What does this result mean? Since both groups saw the character’s eye move, the difference may have to do with how observers interpreted what the eye movements meant. Pelphey suggests that there is a difference in autistic and nonaustitic people’s ability to read other people;s intentions. The nonaustistic observers expected that the character would look at the checkerboard and when that didn’t happen, this caused a large STS response. Autistic observers, on the other hand, may not have expected the observer to look at the checkerboard so the STS responded the same way to both the congruent and incongruent stimuli.
9) What is perceptual completion? Describe the experiment that demonstrates the existence of perceptual completion in infants. What is the role of movement in this experiment? What is the role of attention in determining perceptual completion?
Perceptual completion – the perception of an object as extending behind occluding objects. This is also referred to as achieving object unity.
Because infants are more likely to look at a novel stimulus, we can create a preference for one stimulus over another by familiarizing the infant with one stimulus but not with the other. For this technique, which is called habituation, one stimulus is presented to the infant repeatedly and the infant’s looking time is measure on each presentation. As the infant becomes more familiar with the stimulus, he or she habituates to it, looking less and less on each trial.
Once the infant has habituated to this stimulus, we determine whether the infant can tell the difference between it and another stimulus by presenting a new stimulus. If the infant can tell the difference between the habituation stimulus and the new stimulus, he or she will exhibit dishabituation, an increase in looking time when the stimulus is changed.
If, however the infant cannot tell the difference between the two stimuli, he or she will continue to habituate to the new stimulus, (because it will not be perceived as novel.
Remember that the occurrence of dishabituation means that the second stimulus appears different to the infant from the habituation stimulus.
