26.2 - Attention and Memory Flashcards
Summarise the main types and subtypes of memory/learning.
- Declarative (explicit) -> Conscious memory of facts and events
- Semantic -> Factual information (e.g. location of Eiffel tower)
- Episodic -> Personal experiences (e.g. what you had for breakfast)
- Non-declarative (implicit) -> Modes of learning that are non-conscious
- Skills/Procedural -> Learning skills and habits (e.g. how to ride a bike)
- Category -> Assigning objects/skills in the world into classes for the purpose of generalization, discrimination, and inference (e.g. movie genres)
- Priming -> Where identification of a stimulus is improved by an earlier encounter of that or other stimuli (e.g. being able to complete a partially completed letter once you recognise what it is)
- Associative -> Learning to associate one stimulus with another stimulus (i.e. conditioning).
- Non-associative -> When repeated exposure to a stimulus leads to a change in how intensely it is perceived (e.g. repeatedly hearing a sound in the background may cause you to tune it out).
Compare whether semantic or episodic (both declarative) memories are stored in the long term.
- Semantic memories (i.e. facts) are likely to be stored in long-term memory
- Episodic memories (i.e. experiences) are unlikely to be stored in long-term memory, as the name suggests
What is short-term memory?
[IMPORTANT]
- The process of holding memories for between 3 and 18 seconds, such as the digits of a phone number. It very rapidly decays.
- Note that this is different from the colloquial definition of short-term memory.
Give some experimental evidence for how short-term memory can be assessed.
[EXTRA]
- Verbal short-term memory is assessed using a digit span test (seeing how many digits the individual can remember)
- Visuospatial short-term memory is assessed using the Corsi blocks test (tapping the blocks in the correct sequence)
Where in the brain are verbal and visuospatial short-term memory stored? Give some experimental evidence for this.
- Verbal STM = Left parietal lobe
- Patient KF (Shallice & Warrington, 1970) with a left parietal lesion had a digit span of only 2 but normal spatial span on Corsi blocks and normal long-term memory
- Visuospatial STM = Right hemisphere
- Patient ELD (Hanley et al, 1991) with a right hemisphere lesion had an impaired spatial span but normal digit span and long-term memory
What is working memory?
[IMPORTANT]
- A cognitive system with a limited capacity that can hold information temporarily.
- Working memory is important for reasoning and the guidance of decision-making and behavior.
Describe a model of working memory.
Baddeley + Hitch model → most influential account of WM
3 functionally independent buffers:
*Phonological loop → stores verbal info
*Visuospatial sketchpad → stores visuo-spatial info
*Episodic buffer → integrates ^ information temporarily stored for (perceptual) processing/ comprehension.
Supervisory system controls, coordinates, + regulates these systems.
Responsible for task-shifting/ retrieval strategies/ selective attention/ inhibition.
Describe the areas of the brain involved in working memory.
One theory suggests:
- Parietal cortex -> This is where short-term memory is stored
- Prefrontal cortex -> This is where manipulation and monitoring of information occurs
How does memory change with age?
- Short-term memory improves during development
- But both short-term and long-term memory decline with age
- The only exception to this is semantic memory (e.g. facts about the world), which accumulates with time
(Reuter-Lorenz, 2009)
Is working memory related to intelligence? Give some experimental evidence.
(Colom, 2008):
- Found that working memory and intelligence were highly correlated
(Jaeggi, 2008):
- Tested whether training working memory can lead to improvements in fluid intelligence
- Found that improving working memory did significantly increase performance on a non-verbal intelligence test
- However, not all other studies have been able to replicate this finding and it remains controversial
Where is episodic long-term memory stored in the brain?
The hippocampus is involved in consolidating the memories, which are ultimately largely stored in the cerebral cortex (i.e. they pass from the hippocampus to the cortex).
Compare the regions of the brain involved in short and long-term memory.
- Short term = Parietal cortex (and prefrontal cortex in working memory)
- Long term = Hippocampus (medial temporal lobe) and cerebral cortex
Describe the case of patient HM and what this tell us about long-term memory.
[EXTRA]
- Patient H.M. suffered from epilepsy and had his hippocampus and parahippocampal regions removed as a possible treatment
- The result of this was that he developed severe anterograde amnesia, meaning that he was unable to form new memories
- He also had graded retrograde amnesia, meaning that his long-term past memory was more affected most regarding memories just before the operation -> He was able to recall childhood memories but struggled with memories of the years before the operation
- This demonstrated the importance of the hippocampus in forming episodic long-term memories
How can patient HM’s graded retrograde amnesia be explained?
- Memory consolidation is thought to work by initially sotring the memories in the hippocampo-cortical regions
- It is then eventually transferred fully to the cortex
- This explains why patient HM’s loss of the hippocampus caused him to not only develop anterograde amnesia, but also lose some recent past memories that had not yet been fully consolidated
What is Ribot’s law?
[IMPORTANT]
- The idea that new memories are more likely to be lost than old memories.
- This can be explained by the theory of memory consolidation, where memories are initially stored in the hippocampo-cortical regions and then eventually transferred fully to the cortex -> Once it is fully consolidated, it is less likely to be lost
What are the causes and symptoms of Korsakoff syndrome?
[IMPORTANT]
- It is a syndrome characterised by severe memory loss and confabulation
- It is caused by thiamine (vit. B1) deficiency, which is often seen in alcoholics
- The mammillary bodies in the Papez circuit seem to be particularly affected
- It is reversible
Give some experimental evidence for the “last in, first out” theory of memory.
[EXTRA]
(Butters & Cermak, 1986):
- Studied a professor who developed Korsakoff’s syndrome shortly after writing his autobiography
- Assessment showed that the professor retained far better memory of events that were a long time ago, compared to just before his diagnosis
What is procedural memory?
A form of implicit memory relating to how to perform different actions and skills (e.g. riding a bike).
What is priming?
Where identification of a stimulus is improved by an earlier encounter of that or other stimuli (e.g. being able to complete a partially completed letter once you recognise what it is).
Amensics typically have lesions of…
Medial temporal lobe (e.g. hippocampus)
Are procedural memory and priming affected in patients with hippocampal lesions (i.e. amnesics)?
No, they appear to be intact:
- Patient HM was able to learn in a mirror tracing task (procedural learning).
- Dr Claparède pricked an amnesic woman in the hand with a pin every time he shook her hand. Even though she couldn’t remember him each time she saw him, she became aversive to shaking his hand (priming).
Give an example of a condition with medial temporal lesions that leads to amnesia.
Alzheimer’s disease (it tends to affect the entorhinal cortex and then the hippocampus)
Describe the concepts of primancy and recency.
[IMPORTANT]
- When information is presented in a list, we tend to remember the most from the start of the list (primancy) and end of the list (recency).
- Clinical relevance: Patients recall best the information you give them at the beginning and end of the consultation.
How can recency be lost? What is this evidence for?
- The recency effect is lost when there is gap between the end of the information and recall that is filled with an activity, such as counting back in 3s.
- Counting backwards prevents rehearsal and retention of words in short-term memory. Thus, this demonstrates that recency is likely to be mediated by STM.
Are recency and primacy affected in medial temporal lobe lesions (e.g. hippocampus)?
- Recency is not affected, because it is mediated by short-term memory, which is not controlled by the medial temporal lobe
- Primacy is affected, because it is mediated by long-term memory, which is controlled by the medial temporal lobe
Memory is…
Reconstructive
What is meant by memory being reconstructive?
We do not store and recollect memories exactly as they are, but much rather we reconstruct memories based off information and previous knowledge.
Give some experimental evidence for memories being modified or even created.
[EXTRA]
(Loftus, 1974):
- Participants watched a video of a car crash
- They were then asked to judge the speed at which the cars crashed
- The average speed the participants estimated varied depending on the verb that was used
- Some also falsely recalled seeing broken glass
(Wells, 1998):
- Studied eyewitness testimony
- Participants watched an 8 second security video and asked to pick the gunman from photographs.
- Every observer picked someone despite the fact that none of the people in the photos was the gunman.
What is confabulation?
[EXTRA]
- False memories without conscious knowledge of their falsehood.
- These are often plausible, but imaginary, recollections of an event or sometimes a grand account of personal life.
- They occur after orbitofrontal cortex damage and in Korsakoff’s syndrome, perhaps as a consequence of failures in control over memory retrieval.
Compare how and where episodic and semantic long-term memories are stored.
- Episodic memory is first stored in the hippocampus (medial temporal lobe) and then consolidated in the cortex.
- Semantic memory is eventually found to be stored in the left temporal pole. It is quite likely that the hippocampus plays a role in the formation of these memories, but there is more uncertainty about this.
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 are the disorders of attention mentioned in the spec?
[IMPORTANT]
- Extinction
- Unilateral neglect
- Goal neglect / Dysexecutive syndrome
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.
Which parietal cortex is more commonly lesioned in unilateral neglect?
Right
Do attention disorders usually feature lesions of the early visual centres?
No, it is usually later than that. The patient can usually see everything fine, just can’t perceive it.
Why do right hemisphere strokes lead to more profound unilateral neglect?
The left hemisphere is more concerned with speech and language.
If a stimulus activates the primary visual cortex, does this mean it will be perceived?
- No, because attention disorders can cause a lack of perception, so the stimulus is not consciously perceived (Rees, 2000).
- This can be studies using fMRI.
Give some interesting experimental evidence for unilateral visual neglect. Halligan 1988
(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
What are some drugs that may improve attention?
[EXTRA]
- Methylphenidate (ritalin) and amphetamines
- Modafinil
- Donepezil
What lesions may cause problems with executive control over attention (a.k.a. cognitive control)?
Frontal lobe
Give an example of a test that may be used to test executive control over attention (a.k.a. cognitive control).
- Stroop test
- In this test, executive attention must be used because the words do not correspond to the colours, so normal reflex reactions to reading them do not work and must be overcome
What is dysexecutive syndrome and what causes it?
[IMPORTANT]
- It is a lesion of the frontal lobe
- It features impaired executive functions, including the planning, focusing attention and behavioural
- An example of symptoms is that the patient may struggle with the Stroop test
What is the difference between:
- Simultanagnosia
- Unilateral neglect
- Visual extinction
- Dysexecutive syndrome
- Simultanagnosia -> Cannot perceive more than one object at once, anywhere in the visual field
- Unilateral neglect -> Cannot perceive stimuli on the contralesional side
- Visual extinction -> Cannot perceive a stimulus in the contralesional field WHEN an stimulus is also shown on the ipsilesional side
- Dysexecutive syndrome -> Problems with executive control
How are attention and sensory stimuli related? Give some experimental evidence.
[IMPORTANT]
(Veldhuijzen, 2006):
- Had subjects perform high attention load and low attention load tasks while being subjected to painful stimuli.
- Results indicate that highly demanding attentional task performance and pain processing interfere as a result of difficulties in allocating attention.
Furthermore, decreased attention can lead to sensory loss and leave the individual with a reduced ability to recognise inputs, potentially causing them to miss vital information that would improve outcomes.
How are attention, planning and intelligence related?
[IMPORTANT]
There are strong links between attention, short term memory, and planning ability through executive control, as well as better attention usually linking to improved outcomes and completion of tasks that can make an individual seem intelligent.
Summarise which brain areas are involved in attention.
- Right inferior parietal lobe
- Responsible for spatial processing in attention
- Lesions lead to neglect of the left visual field, despite the eyes and visual cortex being intact
- Frontal lobe
- Responsible for executive control over attention (top-down hypothesis)
- Lesions can lead to poor scores on the Stroop colour and word test as a result of decrease attention to the contents of the visual field
- Right frontal and parietal lobes (again)
- Involved in sustained attention (staying focused on a task in the long-term, driven by goal-motivated behaviours)
- Frontal eye fields
- Involved in shifting attention using the gaze
What is anterograde/ retrograde amnesia?
Anterograde -> inability to create new memories
Retrograde -> inability to recall memories from before onset of amnesia
What is the temporal gradient in memory?
Temporal gradient in memory refers to a pattern of retrograde amnesia where there is greater loss of memory for events from the recent past compared to events from the remote past
