Topic 5- attention

Question 1

Outline the difference between neuroscience and psychology.

Answer 1

Psychology and neuroscience are connected by the inherent goal to understand the mind and the brain but where cognitive neuroscientists mainly use the technology, cognitive psychologists use experimental tasks to study the mind through behaviour.

Question 2

What is attention?

Answer 2

Studying attention involves studying focus and how it operates.

Even though different things may be competing for your attention it is possible that only some messages will reach your conscious awareness and this complex process involves some sort of filtering mechanism that is yet to be fully understood.

Question 3

What is dichotic listening?

Answer 3

Listening to input from one ear (attended channel) while ignoring that from the other (unattended channel).

Recall of content (also known as shadowing) has been found to be almost perfect for the attended channel but almost non-existent for the unattended one.

The cocktail party effect refers to the ability to focus one’s attention a particular stimulus while filtering out a range of other stimuli .

Question 4

Explain Broadbent’s filter model.

Answer 4

2 stages- A non-selective stage captures and processes all incoming sounds whilst the selective stage is limited in capacity and can thus only be concerned with distinct sounds.

He argued that a filter regulates selection of sounds to progress to that second stage according to distinct, physical, surface-level characteristics and that semantic processing is carried out after the information has been filtered by the selective stage.

Broadbent has been criticised for his argument that only perceptual characteristics of an unattended message are processed.

A particularly famous yet controversial study for example reported that participants who were conditioned to associate certain words with an electric shock still exhibited a galvanic skin response, indicating emotional arousal, when presented with these words in an unattended message, even though they generally could not recall them consciously. This indicates that some deeper level of processing of the meaning of those words took place.

Question 5

Explain Deutsch and Deutsch’s late selection model of attention.

Answer 5

Deutsch and Deutsch proposed an alternative view of late selection in which they argued that both the unattended as well as the attended message get processed, including the perceptual and semantic features, but only the attended message is later made available to conscious memory.

Question 6

Explain Treisman’s early attenuation model.

Answer 6

Attenuation basically means ‘to a lesser extent’ and this model suggests that suggesting that whilst the unattended message gets processed it does so to a lesser degree.

Question 7

Explain the difference between exogenous and endogenous control of attention.

Answer 7

Exogenous:

• bottom up
• the type of attention we do not control; it is demanded by an external stimulus that captures your attention

Endogenous:

• top down
• you choose what you attend to; your intentions and interests direct your attention

Question 8

Explain inattentional blindness.

Answer 8

This happens in situations where you are paying attention to one stimulus but not the other, and as a result you do not notice a change in the unattended stimulus.

Mack and Ross: participants were asked to focus on a cross in the middle of the screen and were told that another cross would appear and they would have to determine whether the horizontal or vertical line on the cross was longer. The fixation cross was changed into shapes or even strings of letters and most participants did not notice. This is also applicable to sound (inattentional deafness) and touch (inattentional numbness).

Question 9

Explain change blindness.

Answer 9

When we see two similar images flickering back and forth disrupted by a blank screen we are not able to see the difference between the images at first or even for a while.

Both change blindness and inattentional blindness demonstrate the limits of our attention.

Question 10

What is sustained attention?

Answer 10

Sustained attention is often defined as the maintenance of vigilance, so rather than exerting control over your focus as you do in selective attention, sustained attention is related to survival instincts

Question 11

How is sustained attention measured in humans?

Answer 11

Sustained attention is often measured using the Sustained Attention to Response Task (SART).

This involves presenting numbers 1-9 ) sequentially or randomly, and asking participants to continuously press this button unless the number 3 is presented. The score on this task, so the numerical indicator of sustained attention, is often the number of commission errors, so the number of times erroneously responded to the number 3, or the number of omission errors, so the number of times not responded to a number that is not 3.

There are two versions of this task – the fixed version where numbers are presented in the correct order from 1 to 9, and the random version where they are presented randomly.

Research involving traumatic brain injury patients has demonstrated that performance on this task is reliably associated with brain damage severity and informant-reported everyday attentional failures.

Some research suggests that the SART is not a measure of sustained attention but rather a measure of response inhibition, so the ability to resist a response to the number 3.

Question 12

How do we know that there is an involvement of non-visual mechanisms in situations in which we actively attend to a stimulus?

Answer 12

Early research by Posner and Snyder has found a way of doing this using a so-called priming paradigm. In these paradigms participants are usually presented with a prime which is either the same or similar to a target stimulus before being presented with said stimulus. In this study participants were asked to indicate whether two letters were the same or different – so, for example, if they saw two As the answer was yes whereas if they saw an A and a B the answer was no. Therefore, this was a very simple task. Before seeing these letters, participants saw a warning just above where they would appear. There were three types of warnings: a neutral warning which was just a plus sign, a prime warning which was a letter which also appeared in the target pair, and a misleading warning which was a letter not appearing in the target pair. You can see examples of these warnings in the blue box on the slide. The likelihood of the prime warning appearing was either 80%, 50%, or 20% in this study. In other words for some participants the warning was very reliable, whereas for others it was not very helpful at all.the prime warning was always associated with a benefit regardless of its reliability, however, only when the prime warning was very reliable was the misleading warning significantly associated with a cost.

This tells us that expectation-driven priming effect demonstrates that merely being prepared to see a stimulus is enough to facilitate its processing and this system is only disrupted by a different stimulus when a large proportion of resources is directed towards the expected stimulus. In turn, this demonstrates that a wider system is involved in processing information even before it is presented in the visual field. It also demonstrates the limits of such a system.

Question 13

Why is attention commonly compared to a ‘spotlight’?

Answer 13

This analogy captures that, even though a space might contain many different elements, our conscious awareness is limited to either what we attend to or to what our attention is directed towards.

Question 14

Explain the attention network test.

Answer 14

A study by Fan and colleagues used the attention network test to demonstrate this. In this task participants were presented with a number of different screens: the first screen showed either a fixation cross, a cue, or both. This was followed by a screen featuring just the fixation cross and was then followed by the target trial. The target trials always featured a fixation cross and 5 arrows. These arrows were either above or below the cross. Furthermore, on easy trials all arrows pointed in the same direction, whereas on difficult trials the central arrow pointed in the opposite direction to the others. It was the participant’s task to indicate the direction of this arrow.

Question 15

Explain what was found in the attention network test about the alerting system.

Answer 15

In one condition participants did not see a cue, whilst in the others they either saw a centre cue appearing in the centre of the screen or a spatial cue appearing where the arrows would appear later on.

Alerting was measured as the performance following the centre cue in relation to the performance following no cue. In essence, the latter served as a baseline, whilst the former, the centre cue, alerted the participants to the upcoming stimuli. The degree to which such a cue facilitates processing is a measure of sustained attention. Previous research involving patients implicated the frontal and the parietal lobes, especially in the right hemisphere of the brain, in the ability to maintain attention. Therefore, Fan and colleagues were not surprised to see these areas to display increased blood flow on these trials.

Question 16

Explain what was found in the attention network test about the shifting system.

Answer 16

The areas of the brain associated with alerting were hypothesised based on their association with the norepinephrine network, which is associated with the maintenance of an alert state.

Orienting on the other hand requires a person to shift their attention from one thing to another. Fan and colleagues therefore expected the involvement of the superior parietal region and the temporal parietal junction in the orienting condition in particular because of their previously established role in shifting attention. Once again it was successfully predicted that activation would be found predominantly in the right hemisphere.

The difference between the orienting and the alerting condition in the task was that this time the effect was calculated by subtracting performance following the spatial from performance following the centre cue. This was done because, in the case of the centre cue, the participants need to shift attention to the location of the arrows once they appear.
This is not the case in the spatial cue condition, therefore, this difference captures the cost associated with shifting attention.

Question 17

Explain what was found in the attention network test about the executive.

Answer 17

Executive functions, as opposed to automatic behaviours, encompass the processes involved in the active control of attention. In the case of the study of Fan and colleagues this was operationalised by calculating the difference in performance on incongruent, so difficult, and congruent easy trials.

A wealth of previous research has demonstrated the involvement of the anterior cingulate cortex as well as the prefrontal cortex in executive function. This is also what the study found.

Whilst activation in the hypothesised areas did occur and they were distinct from one another for the three respective functions, other areas of the brain were also engaged, for example the posterior regions in the executive control condition.

Question 18

What is hemispheric assymetry?

Answer 18

The fact that due to our neuroanatomy, the right hemisphere of our brains processes elements in the left visual field whereas the left hemisphere processes information in the right visual field.

Question 19

Explain unilateral neglect syndrome/visuospatial neglect and some research associated with it.

Answer 19

Unilateral neglect is usually caused by right hemisphere damage from stroke, leading to difficulties in attending to stimuli in the left perceptual hemifield.

Patients may not respond to individuals trying to interact with them from the left, they may only shave the right hand side of their face, or they may only apply makeup to the right hand side of the face. Crucially, the issue here is not with their vision but rather the fact that they are not aware of elements of the left visual field.

This is nicely illustrated in a study by Bisiach and Luzzatti who asked residents of Milan with damage to the right parietal cortex to imagine the Piazza del Duomo, which they all knew well. Depending on the standpoint participants were told to imagine the square from, they recalled only shops and cafes to the right-hand side demonstrating that it was not their knowledge of the location of things that was impaired but rather their awareness.

A further study demonstrating that visual neglect is not about vision and, strikingly, may not even always be about space was conducted by Behrmann and Tipper. When showing participants with right parietal cortex damage a barbell which featured a stimulus, patients took a lot longer and made significantly more errors when the stimulus was on the left-hand side of the barbell. However, when slowly rotating the barbell by 180 degrees the opposite pattern emerged. Patients detected the stimulus in the formerly right location, which was now on the left, more successfully. This study demonstrates that once a focus has been established patients with visual neglect maintain it regardless of a change in location.

Furthermore a study by Volpe and colleagues demonstrated that, whilst the conscious recollection of a stimulus on the left may not be possible for a patient with visual neglect, some unconscious processing may still take place. The patients in this study were actually able to name objects on both the right and the left side of the visual field when no other objects were present. This demonstrates how diverse this condition can be. As you can see in the second image from the left it appears that the right hemisphere of these patients was successfully able to communicate with the left hemisphere via the corpus callosum, which facilitates communication between the two hemispheres. As expected when two objects were present patients could only name the one on the right, however, when asked whether the two objects were different patients performed above chance indicating some awareness, although unconscious, of the object on the left.

Another example of this comes from a paper by Marshall and Halligan who simultaneously presented patient P.S. with two drawings of houses. Despite the patient not being aware of any differences between the drawings and believing it was silly that she was asked to choose between them, when asked where she would prefer to live she choose the house that was not on fire nine out of eleven times.

Imaging evidence of this effect comes from a study by Rees and colleagues who use imagery which is processed in specific areas of the brain, namely faces and houses. As expected, when presented with a trial similar to the left of the slide, the patient in the study reported only seeing the house but not the face, however, fMRI data revealed activation in the fusiform face area which is associated with the processing of faces. Taken together, all this evidence suggests that there is a difference between conscious awareness and unconscious processing in patients with right parietal cortex damage.

Question 20

Explain testing on patients with damage to their prefrontal cortex.

Answer 20

This area of the brain is associated with the executive system. Damage to this area, therefore, leads to problems in the control of attention.

One of the psychological problems Gage reportedly displayed after his accident was an inability to successfully make and execute plans. Similarly, patients with damage to the prefrontal cortex exhibit what is referred to as goal neglect. In order to measure this, patients are usually given a very complex figure. Patients ned to look at the figure and plan how to recreate it; those with prefrontal cortex damage struggle to do this effectively as it requires planning and execution of a plan.

Another measure commonly used to test executive function abilities in patients but also in healthy individuals the Wisconsin Card Sorting Test. Participants are commonly asked to sort the card on the bottom right of the image by colour at first. After a while they are asked to switch and to sort by shape or number of shapes instead. What we find is that patients with damage to the prefrontal cortex are unable to switch between tasks and continue to sort by colour.