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EMOTION AND MEMORY :PENCIL2: P+C2 LECTURE 8 - Coggle Diagram
EMOTION AND MEMORY
:PENCIL2:
P+C2 LECTURE 8
Computer Memory vs. Human Memory
Emotional states interact with memory systems influencing how efficiently they function
Bias what information can be readily retrieved
Arousal and Memory
Arousal, Memory and Embarrassment:
When we do embarrassing things, it would be good to be able to forget they ever happened.
Unfortunately, these memories often remain vivid for ourselves, and even worse, they can remain vivid for other people as well!!
This is because the negative emotional reaction of embarrassment leads to arousal, and arousal can help store memories.
Yerkes-Dodson Law (1908)
Arousal changes throughout the day, and also throughout weeks, months, etc.
International Affective Pictures (IAP)
Bradley et al. (1992)
A key issue is to decide whether it is general levels of arousal that influence memory or whether it is the kind of emotion (good vs. bad) that has an effect.
Participants viewed pictures and are asked to recall immediately or 1 year later.
Recall task was a brief description of the picture.
Results...
Better immediate recall of highly arousing images but no significant difference between pleasant & unpleasant.
One year later still better recall of highly arousing images and no effect of valence.
Not statistically significant.
Effect lasted a whole year later.
People were more likely A key issue is to decide whether it is general levels of arousal that influence memory or whether it is the kind of emotion (good vs. bad) that has an effect.
Emotional Stimuli vs. Emotional Memory
Activation of the arousal state can facilitate memory for neutral stimuli, like numbers.
Participants were presented with word-digit pairs and were asked to remember them.
Half of the words were emotional, and half were neutral.
E.g. ‘Field - 37’ (neutral)
E.g. ‘Suffering - 35’ (emotional)
Then, either immediately or 24 hours later, the words were provided and participants were asked to recall the neutral number that was associated with the word.
‘Field’ → 37
E.g. ‘Suffering’ → 35
Although no differences in number recall immediately,
after 24 hours numbers paired with emotional words were significantly better recalled.
Hence better consolidation into memory for stimuli (such as numbers) associated with emotional context.
Increased arousal facilitates memory
Exciting positive stimuli (e.g. image of ski slope)
Exciting negative stimuli (e.g. image of plane crash)
...But also neutral stimuli such as numbers (when paired with arousing words)
Experiment
Told to focus on the word in the middle and ignore the word on the side.
97% accurate in later recall of the central word, so focused attention.
Results
Assessed memory for peripheral words either immediately or 24 hours later.
Found recall of the neutral peripheral/ignored words declined but the emotional/arousing words were better recalled 24 hours later.
This suggests not more attention as a mechanism, as the words were ignored, but
automatic encoding of emotion facilitates consolidation.
The role of attention
Sharot & Phelps (2004)
In an aroused state > focus more attention?
Or is it more of an automatic process?
Neural mechanisms of arousal-memory interactions
(1) Patients with damage to the amygdala do not show the improved memory for arousing stimuli.
LaBar & Phelps (1998)
At recall 1 hour later controls showed an advantage for emotional/arousing stimuli but people with damaged amygdala did not show this emotion advantage.
(2) Neuroimaging studies reveal a correlation between strength of amygdala response to an emotional stimulus at encoding and later recall.
Hamann et al. (1999)
That is, while encoding the stimulus, if the amygdala is more active the stimulus is more likely to be recalled later.
Stress and Memory
Increased arousal improves memory consolidation.
This is a useful system because events that are arousing are important and need to be remembered.
However, prolonged stress and extreme arousal can have the opposite effect: they can impair memory processes (
Yerkes-Dodson Law
)
The effects of stress can be short or long term
Short term stress is a state of panic.
A sudden panic attack impairs decision making and blocks access to memory.
Situations such as examinations or making a best-man speech at a wedding.
Idzikowski & Baddeley (1983)
Study
: A first talk at a conference can trigger these transient episodes.
Participants were tested on a number of tasks just before giving their first talk or at a neutral period.
Heart rate increased and they reported higher levels of stress just prior to the talk.
Short term stress: Memory
In digit memory span tasks, a set of numbers (e.g., 8, 3, 4…) are presented and then people are asked to report them back in the correct order.
The span measures how many they can recall.
Working memory capacity was reduced in the stressed state prior to the talk.
Verbal fluency requires retrieval from memory.
People are given a letter and asked to recall as many words as possible that start with that letter.
One minute is allowed for each letter.
Again, pre-talk
stress reduces a person’s ability to retrieve information from memory.
Short-term stress: Attention
Stroop interference
This measures selective attention ability.
That is, how well distractor word meaning can be inhibited while naming ink colour.
This selective attention process
was not
affected by pre-talk stress.
Results
Short-term memory:
Impaired
Verbal fluency:
Impaired
Stroop interference:
Unaffected
Therefore short-term stress appears to affect memory but not attention in this study.
Long-term stress
Where an individual is under stress for prolonged periods there are hormonal changes
Glucocorticoids are stress hormones released from the adrenal gland.
McEwan & Sapolsky (1995)
Stress in rats increases the release of Glucocorticoids:
Reduced firing rate of hippocampus neurons.
Impaired memory performance.
Hippocampal atrophy after long term exposure to stress.
It is not ethical to place humans under prolonged periods of stress, so the animal studies have no human equivalent.
Alternative approaches
Newcomer et al. (1994)
First, a
drug that artificially increases the level of glucocorticoids
can be given and
compared to a placebo.
After 4 days there was evidence for impaired memory performance.
PTSD
Long term effects of a severe stressful event such as being assaulted, traffic accidents, warfare.
It often involves flashbacks: extremely vivid memories of the scene of the initial terror. This can be accompanied by nightmares and general state of anxiety.
Two people experience the same stressful event. Why does one of them develop PTSD while the other appears to be unaffected?
Support for animal models
People with PTSD who have suffered from these disorders for several years show signs of hippocampal atrophy.
E.g. 12% reduction in volume of the hippocampus in PTSD.
However...
(1) The PTSD could have caused the hippocampus to shrink.
(2) The hippocampus may already have been smaller and this is what made the person vulnerable to PTSD.
A typical comparison would be between a person with PTSD and a control. This could show reduced hippocampus.
E.g. Twin A2 and Twin B1
But this critical comparison is between the identical twins who never experienced stress. We would expect both would have normal hippocampi, but this is not the case.
Twin A2 and Twin B2
Results
The results support the idea that individuals who have a normal hippocampus are protected from developing PTSD.
We know that during stress the emotional encoding in the amygdala causes the release of adrenaline and cortisol, stress hormones that trigger fight or flight.
Perhaps the larger hippocampus enables people to resist these stress effects.
When people are exposed to combat >> size of the hippocampus predicts PTSD.
Interestingly the hippocampus size of a twin who has never experienced war predicts the PTSD of their twin sibling.
Long-term stress in tree-shrews
Fuchs (2005)
Tree shrews live in isolation or pairs and defend territories.
This produces a natural stressful situation when a male has visual and olfactory exposure to a male he has been defeated by.
Loss of weight, less active, disturbed sleep, increased cortisol.
This
stress reduces axon branching in the hippocampus
when comparing unstressed (left) to stressed (right) tree shrews.
Mood and Memory
State-dependent retrieval
For example, many people report that things said and done while drunk cannot be recalled when sober.
However, when next in the drunk state the memories come flooding back.
Putting something away safely while drunk cannot be found when sober, only when drunk again does the hidden location come back to mind.
Such context specific retrieval has been shown in experimental settings where information learned while drunk is better retrieved when drunk again than when sober.
Extreme mood and memory
In more extreme cases such as assault and murder, these acts are often carried out in states of extreme emotion such as rage and while under the influence of drugs.
In up to 30% of such cases the culprit claims to have no memory.
Often it is necessary to resort to hypnosis to place people back into the emotional context state, and then accurate recall is achieved.
Bobby Kennedy
Sirhan Sirhan allegedly assassinated Bobby Kennedy in a hotel kitchen in 1968.
He claimed no memory of this violent act.
However during hypnosis he again went into a highly emotional state and relived the event.
But when returned to the normal state he had no memory and denied it was him speaking in the recording.
Selective encoding of mood congruent material
Mood state determines memory retrieval
Negative mood:
Faster retrieval and more negative memories from episodic memory.
Better learning and recall words like “failure”.
-
Positive mood:
Faster retrieval and more positive memories retrieved.
Better learning and recall of words like “success”.
Mood Induction
One of the main techniques for studying the effects of mood on perception and memory.
Initially participants fill in a questionnaire to assess mood.
This is required to see whether the mood induction technique worked by shifting their mood either positively or negatively from the starting point.
Then mood induction procedure such as the Velten (1968) technique where participants read self referential statements designed to make them happy or sad, e.g. for sad states:
“Things have been going badly for me lately”.
“I’m feeling very lonely, isolated and depressed.”
Other approaches show a funny or sad movie or listen to exciting or depressing music and ask participants to feel whatever the movie/music depicts.
Then a second questionnaire to check the manipulation shifted mood in the expected direction.
Automatic mood induction via odor
Most mood manipulations are explicit, such as the Velten procedure where people read aloud statements that express positive or negative feelings, or they are exposed to music or images that are positive or negative.
These tasks require people to actively engage with the stimuli and move into different emotional states: “The news story reports terrible things, the world is a dangerous place.”
Experimenter bias: Participants might think they need to maintain their mood state, and hence actively select mood congruent information from memory.
Need a technique that
avoids explicit emotion related cognitive activity
and where people do not know emotion effects on memory are being investigated.
Odor
Use odor to induce positive and negative states.
Odor is a basic perceptual stimulus that often has emotional properties.
Positive: the scent of a flower, fresh fruit, food.
Negative: the smell of sewage, infection.
Experiment
While exposed to the pleasant or unpleasant odor participants listened to neutral words (e.g., “walk”). Their task was to recall a specific memory from their life related to the word.
At the end of the experiment they heard a recording of their own responses and then rated how happy the memory was.
At the end of the experiment they heard a recording of their own responses and then rated how happy the memory was.
Implications for clinical issues: pleasant odor reduces retrieval of negative memories causing anxiety and depression.
Business/work environment:
More creative/contented work-force.
Positive associations with a product.
Memory for emotional public events
There are limits to what we can do to study emotion in the laboratory. The emotions and mood states we create must be relatively mild.
This is the classic problem in experimental psychology. The work often lack ecological validity, being distant from the real-world interactions' humans experience.
One way around this problem is to study real-world events and how these events alter memory and perception processes. Although such “natural experiments” lack the high levels of control seen in the laboratory, they nevertheless provide important insights.
The first such study was the assassination of President Kennedy. (
Brown & Kulik, 1877
)
Assassination of John. F. Kennedy (1963)
People asked to recall details of the event: where they were and who they were with etc.
Many people felt they had very accurate memories, almost like a photograph.
These were termed
flashbulb
memories.
A sort of “print now” in the memory system for extremely important and emotional events.
World Trade Centre 9/11
Many people report seeing the first plane hit the towers on the day it happened.
This was not the case as the image came from the general public and was not on TV until the following day.
Emotional Public Events: Unique Memories
These memories appear vivid and accurate, but it is not obvious that they are special and different to other memories.
It is most likely that they reflect memories with a very strong arousal input and that they are unique relative to other memories so there is little interference.
Black people were more likely to have more vivid memories of the deaths of Martin Luther King and Malcolm X than whites because these individuals were of great importance to them.
Positive Memory Bias
Across the world, income levels, age and sex, people tend to report they have relatively happy lives.
Even people with physical and mental impairments report being happy.
Our assessments of our lives are determined by what we recall, and there appears to be a bias in that we recall many more positive memories than negative memories.
Waldfogel (1948)
Asked people to retrieve memories from the first 8 years of their life.
50% were positive
30% negative
20% neutral
Similarly if asked over longer periods of time to note memories that spontaneously come to mind:
49% were pleasant
32% were neutral
Only 19% negative
This memory bias improves our wellbeing.
However, it could just reflect frequency of memory: more good events are experienced.
Therefore we need a controlled experiment where present positive, negative and neutral scenes and then ask people to recall them at a later time.
Is it the case more positive images are reported?
Study
As we have seen, better memory for both positive and negative emotional stimuli when young.
However,
a positive bias emerges as we get older.
As we age and life gets shorter more focus on maintaining wellbeing rather than accurately gathering information and achieving goals.