26.3 - Constraints on Cognition: Human Attention Flashcards
What are the different types of attention?
- Selective attention -> Filtering out irrelevant information to focus on the relevant
- Sustained attention -> Maintaining processing on a certain goal for a long period of time
- Executive control over attention (a.k.a. cognitive control) -> Maintaining focus when the response is not the automatic one (i.e. things are getting difficult)
The spec mentions spatial attention and selective attention.
What is spatial attention?
[IMPORTANT]
Spatial attention involves selecting a stimulus on the basis of its spatial location.
What is selective attention?
[IMPORTANT]
Filtering out irrelevant information to focus on the relevant.
What are the main types of disorders of attention?
- Developmental
- Attention Deficit Hyperactivity Disorder (ADHD)
- Degenerative
- Parkinson’s disease
- Alzheimer’s disease
- Disorders in young adults
- Traumatic brain injury
- Schizophrenia
- Attention lapses (in all people, even without disorders)
Give an example of selective attention.
Our bodies sense lots of touch stimuli, but we filter out lots of these, such as the rubbing of clothes against our skin.
What is the consequence of selective attention?
We can fail to be aware of things that our brains see.
How can selective attention be demonstrated?
Using change blindness demonstrations:
- Two pictures with a very small difference are shown very quickly one after the other
- The viewer is unlikely to be able to notice that difference due to more interesting things happening in the photo
What is the clinical relevance of dealing with patients with attention disorders?
Much of the information given to patients will not be encoded well, especially if they have attention disorders. So it is worth speaking slowly and clearly, emphasising the important information.
What are the two ways in which selective attention can work?
- Bottom-up (stimulus-driven)
- Top-down (goal-driven)
Give an example of bottom-up selective attention.
- This is where a sudden change in your visual field catches your attention.
- For example, a brick being thrown is likely to capture your attention.
Give an example of top-down selective attention.
- This is where our processing is selectively directed towards certain information.
- For example, if you are looking to meet a friend wearing a red coat, you can scan the crowd looking at just the red parts of the crowd.
Give some examples of ways in which we can study spatial selective attention. Name a paper that studies each of these.
- Track where we look (gaze direction)
- Provides a measure of what has captured attention in the visual scene, bottom-up or top-down (Yarbus).
- Show that it is possible to enhance perception
- If attention is deployed to a location, perception should be enhanced there – but at a cost of reduced perception at other spatial locations (Helmholtz).
- Measure how long it takes it to detect a target
- This should be faster if attention is already deployed at the location a target is presented (Posner) or when there are fewer distracting stimuli (Treisman)
Explain Yarbus’ studies about spatial selective attention.
(Yarbus, 1967):
- Showed subjects this patients and tracked their eyes to see where they looked
- Without any prompt, this allowed it to be seen where top-down attention draws our eyes to (e.g. faces, clothes etc.)
- When prompted with tasks like “assess the ages of the individuals”, the eye movement is much more restricted to just faces, etc.
Explain Helmholtz’s studies about spatial selective attention.
(Helmholtz, 1867):
- Had a chart of different letters, with a cross in the middle
- Focused his eyes on the centre cross, but diverted his attention covertly to a corner of the chart (without changing his gaze)
- His recollection of the letters in that corner improved, but worsened in other corners
- This illustrated that attention can be separated from vision and that focusing our attention on certain stimuli improves our perception of them, but it is at the cost of worse perception elsewhere
Explain Posner’s studies about spatial selective attention.
- Used a setup with a central cross and a box on either side
- The subject is told to look at the central cross
- One of the boxes lights up yellow as a “cue” for which box will light up next -> The subject can see this cue in their peripheral vision (covertly moving their attention there without moving their eyes)
- The cue is correct about 80% of the time
- Next, one of the boxes lights up blue and the subject needs to press a corresponding button as quickly as possible
- When the cue is correct, the response time is much faster than when the cue is incorrect, since the subject must shift their covert attention, which takes time
- The difference in time is the invalidity cost
Which parts of the brain are involved in shifting human attention overtly (via eye movement) and covertly?
[IMPORTANT]
- Superior parietal lobe
- Intraparietal sulcus
- Frontal eye fields
Explain Treisman’s studies about spatial selective attention.
- Treisman used visual search tasks, where a subject looks for a certain object within a field of distractors
- When the subject looks for a green T in a field of red Ts, this is known as a feature search -> It is almost immediate and the time to find the T does not vary with the number of objects in the field
- When the subject looks for a horizontal green T in a field of horizontal/vertical red Ts and verticl green Ts, this is known as a conjunction search -> It is slower and the time to find the T increases with the number of objects in the field. This is because the attention must shift between objects and each one must be analysed, which takes time.
Describe Treisman’s feature integration theory.
(Treisman, 1980):
- Suggests that there are various feature maps in the brain, such as for colours, orientations and motion -> These are pre-attentive
- This means that if you are looking for a red shape among green ones, it is easy and fast because you can do it all within these feature maps
- When looking for a conjunction of features (such as a red shape on its side), the brain moves an attentional spotlight across the retinotopic mapping in the brain and looks to see if the features exist in combination at that spot -> This is called feature binding
- In other words, conjugation search is much slower because it requires combination and processing of information
- This integration might occur in the parietal lobe
Give some experimental evidence for feature binding.
[EXTRA]
- A patient who has Balint syndrome, with bilateral parietal lesions, may experience problems with feature binding
- In these cases, the patient may frequently confuse the colours of two letters that are shown next to each other
What is simultanagnosia and who studied it?
- It is the inability to perceive more than one object at a time
- Balint studied this -> He had a patient with bilateral stroke of the parietal cortex, who struggled to see perceive more than one object at a time.
- Luria also studied this -> He showed his patients a star drawn using two differently coloured triangle and the patients could only perceive one of the triangles when looking at it.
What is visual extinction?
[IMPORTANT]
- A disorder that occurs after damage to the parietal lobe
- The patient is able to perceive stimuli on their own in any part of the visual field
- However, they cannot perceive a stimulus on the contralesional side if it is presented alongside a stimulus on the ipsilesional side
What is unilateral neglect?
[IMPORTANT]
- When a patient has unilateral damage to the parietal lobe, resulting in inability to perceive any objects on the contralesional side of the visual field.
- For example, when drawing an object, the patient may only draw half of the object.
Give some interesting experimental evidence for unilateral visual neglect.
(Halligan, 1988):
- Showed patients with unilateral neglect two pictures of houses, one of which is burning
- They asked the patients to select the house they would prefer to live in
- 80% of patients selected the non-burning house because it looked nicer, despite not being able to identify that the other house was burning
- Thus, this implies that visual information may influence our biases, even if it is not consciously perceived
Give some experimental evidence surrounding how sustained attention changes over time.
- Macworth studied the attention of radar operators over time
- The graph showed how this attention declined with time spent at the radar
Which parts of the brain are involved in sustained attention?
[IMPORTANT]
- Right frontal
- Right parietal
Can unilateral neglect be treated?
- Patients may improve scanning to the contralesional side on the training tasks, such as identifying bright flashing lights
- But this does not ‘generalise’ to other tasks in everyday life
