Motivation and emotion/Book/2013/Emotion and memory

Emotion and memory:
How do emotions affect memory?

Multimedia presentation (5 min)

Overview

Emotions can have a very strong influence on memories, during any of the three stages. This influence can be positive in that emotions can help strongly encode memories and help in retrieving older memories. Emotions can also be a negative factor in memories as they can result in forgetting, and also in creating false memories.

The brain regions involved in memories and emotion are the amygdala and the hippocampus. Damage to these areas, and emotional trauma, can result in problems with memory such as amnesia and post traumatic stress disorder.

There are several strategies that can be used to strengthen the link between memory and emotions, and in turn strengthen the memories themselves.

Definitions

Emotion

Emotion is an involuntary, subconscious mental state that occurs as a result of one's environment, situation and event's in one's life (Fox, 2008). It is a positive or negative feeling that usually involves experience, arousal and expression (Burton, Westen and Kowalski, 2009).

Memory

Memory is the way in which the brain stores information.

There are three stages of memory

Encoding - Encoding is the way in which the brain processes and registers information. The information is represented as code that can later be recovered (Burton, Westen and Kowalski, 2009).
Storing - Storing is the brain creating a record in which the information is kept. This can be stored in either short-term or long-term memory (defined below) (Burton, Westen and Kowalski, 2009).
Retrieval - Retrieval is the process through which the brain is able to recall information from stored memory (Burton, Westen and Kowalski, 2009). This involves bringing a long term memory in to the short term memory.

There are three types of memory

Sensory memory - Sensory memory holds information for a fraction of a second, although the representation of the memory remains for further processing (Burton, Westen and Kowalski, 2009).
Short term memory - Short term memory can hold between 5 and 9 items and has a limited capacity. This information is then rehearsed if it has to be stored as a long term memory (Burton, Westen and Kowalski, 2009).
Long term memory - Long term memory can last a whole lifetime and can include memories of experiences, events, numbers, images etc. (Burton, Westen and Kowalski, 2009).

Test your memory

Can you remember what colour this square is after looking away from it?

You have just tested your sensory memory

Can you remember these numbers after looking at them for 10 seconds?

3 9 61 23 55 84 7

You have just tested your short term memory

Can you remember the last time you went to the beach?

You have just tested your long term memory

There are two main types of long term memory

Explicit memory - Explicit memory involves memories that are consciouslly recollected and brought into the short term memory (Burton, Westen and Kowalski, 2009).
Implicit memory - Implicit memory is not consciouslly recalled but instead expressed through our actions (Burton, Westen and Kowalski, 2009).

Emotion and memory

Emotion has been found to have a large impact on explicit memory. There are three main ways this occurs.

The number of events remembered

Events that invoke either positive or negative emotions are remembered more commonly than neutral events (Kensinger and Schacter, 2008). This is especially true when it comes to autobiographical memories, which are memories about the self (Conway, 1990). In memories of events, however, is no significant difference between the number of positive events and negative events recalled (Bradley, Greenwald, Petry and Lang, 1992). This is not the case in autobiographical memories, where memories associated with positive emotions are recalled more than memories associated with negative emotions (D'Argembeau, Comblain and Linden, 2005). LeDoux (1996, in Kensinger and Schacter, 2008) suggested that people who seek positive goals and experiences were ones who remembered more positive memories. He also however theorised that it is important to remember negative experiences and is vital for our survival as it helps us avoid future situations that could be harmful to us.

The vividness of the events remembered

Events or experiences that have a high emotive value are remembered more vividly and clearly than neutral ones. In this aspect, a distinction is made between the terms recognition and recall. Recognition is the idea that you can tell that you have seen someone or something before but you are not sure what the source of that information is, for example, where or when you saw that person. Recall on the other hand, is knowing that you have seen someone or something and actually remember it. While the rate of recognition is similar for emotional and nonemotional stimuli, the rate of recall is significantly higher for emotional words or pictures (Dewhurst and Parry, 2000).

One rare example of the vividness of emotional memories is the phenomenon of flashbulb memories where the memory consists of highly detailed, almost photographic images. This usually only occurs in events with very strong emotions (Brown and Kulik, 1977). There are a few famous events that people report to have flashbulb memories about such as the 9/11 terrorist attacks and the assassination of John F. Kennedy (Budson et al., 2004). Memories that elicit strong emotions are more likely to be remembered more vividly, not only in great detail, but as if the event was being experienced again (Kensinger and Schacter, 2008).

Studies have found that there is a difference in the quality of the memory depending on the valence, or whether the memory is based on positive or negative emotions (Storbeck and Clore, 2005). Positive memories are more likely to have more errors in retrieval as those in a good mood tend to focus on the overall experience, whereas those in a negative mood are more likely to focus on the details of an experience (Bless et al., 1996). The valence does not affect the quantity of the memories, only the quality of them.

The amount of detail of the events remembered

There is varying research to demonstrate whether there is a difference in the details of a retrieved memory based on the valence of it. The majority of the research suggests that negative memories seem to have a higher level of detail than positive memories (Kensinger and Schacter, 2006). Another study (Buchanan and Adolphs, 2002) found that emotions can help in remembering the gist or general semantic theme of an experience, it can actually hinder the encoding of the details of the situation. This is known as the central/peripheral trade-off where central information is attended to but memory for peripheral information is impaired (Funk and Hupbach, 2013). For example, you will remember the details of the dog that bit you, but not the details of the surrounding environment. According to Mather (2007) arousal leads to a narrowing of attention, focussing only on the central details of the memory, and not the context. He called this the object-based framework.

These issues can be avoided by engaging in certain strategies where encoding is improved by explicitly trying to encode peripheral details (Funk and Hupbach, 2013).

Brain regions and processes

"An experience may be so exciting emotionally as almost to leave a scar on the cerebral tissue."

- William James (in MacLeod, 2006)

Brain regions and processes play a role in the encoding, storing and retrieval of memory. The 'scar' in the quote above is based on the scarring circuits that are formed by the release of the neurotransmitter noradrenaline during the creation of a memory of an emotional event (MacLeod, 2006). The limbic region of the brain is activated in the processes of emotions and memories.

The amygdala and hippocampus are two areas in the temporal lobe of the brain that are involved in memories. These two areas usually work separately, but in situations where there is emotional arousal, the areas form a link and act together (Phelps, 2004).

The amygdala

The amygdala usually works in emotional processes such as the learning of fear (Kalat, 2009). In the process of emotion related memories, the amygdala works in the encoding and storage stages of memory (Phelps, 2004). Neuroimaging studies have shown that the amygdala is activated during the encoding of emotional information, but not neutral information. This has been demonstrated in patients who had damage to their amygdala and did not show increased memory for emotional events (Kensinger and Schacter, 2008). Emotional experiences that show the highest level of amygdala activity during encoding are the memories that are most likely to be recalled (Hamann, 2001). While the amygdala has been shown to be important in the encoding process (Dolan, Lane, Chua and Fletcher, 2000), studies have also shown that it is active during the retrieval memories, more so those with high emotional value than those with neutral value (Maratos et al., 2001; Smith et al., 2004, in Kensinger and Schacter, 2008). A stronger emotional memory means it is more likely that the memory will be retrieved (Dolcos, LaBar and Cabeza, 2005). High levels of activity in the amygdala is also linked to recalling memories more vividly (Dolcos, LaBar and Cabeza, 2004). While the amygdala has been shown to increase the number of memories recalled, it has been theorized that it can also actually hamper levels of attention (Phelps, 2004). This is known as attentional blink and was demonstrated when subjects in an experiment could not encode detail from a second non-arousing stimuli, after an arousing stimuli had been presented (Anderson and Phelps, 2001 in Phelps, 2004).

The hippocampus

The hippocampus area of the brain is important in declarative and episodic memories (Phelps, 2004). The activation of emotions in the memory process is strengthened in the hippocampus in regards to episodic memories, as it attaches emotions and the interpretation of events to the memory (Phelps, 2004). Declarative and episodic memories do not get stored immediately by the hippocampus, instead there a period during which the memory can be lost or strengthened and stored. After this process, called consolidation, the retrieval of the memory does not depend on the hippocampus. During the consolidation process, the amygdala activates stress hormones that strengthen emotional memories as events that invoke strong emotions are more likely to aid survival (Phelps, 2004).

The interaction between the amygdala and the hippocampus

Studies (Dolcos, LaBar and Cabeza, 2004; Kensinger and Corkin, 2004) have shown that the interaction between the amygdala and the hippocampus is essential for strong emotional memories to be formed. One particular study (Richardson, Strange and Dolan, 2004) was conducted on patients with amygdala atrophy and patients with hippocampus atrophy. They found that amygdala atrophy was negatively correlated with the activity in the hippocampus during the encoding of emotional experiences. They also found that hippocampus atrophy was negatively correlated with amygdala activity. This means that the higher the amount of damage to the amygdala or hippocampus, the less activity there is in the hippocampus or amygdala respectively. Another study was conducted in which it was shown that the amygdala and hippocampus interacted to encode emotional words while only the hippocampus was active when encoding non-emotional words (Kensinger and Corkin, 2004 in Kensinger and Schacter, 2008). The amygdala enhances memory by increasing perception and selective attention and therefore making it a priority in the hippocampus (Phelps, 2004). The amygdala itself is not necessary in forming memories, but it enhances the memory by incorporating emotions (Phelps, 2004).

Problems with emotion and memory

Problems can arise when emotions influence memories. These can result in creating memories of events that did not exist, or losing memory for events that did occur.

False memories

The idea of false memories has been controversial in cases of childhood sexual abuse where memories are falsely retrieved with the help of a clinician (Del Monte, 2001). False memories involve believing that a memory is of a real experience or event when it has actually been fabricated through suggestion. Studies have been done on false memories where subjects have reported recognising related words instead of the target word (Clancy, Schacter, McNally and Pitman, 2000). For example if the target word is pillow, words such as bed, blanket, sheets etc. were 'recalled' even though they were never actually presented.

In the case of Beth Rutherford, a young girl incorrectly remembered being raped, getting pregnant and having to abort the fetus herself between the ages of 7 and 14. With the help of a church counsellor during therapy, Beth falsely retreived memories of her father raping her and impregnating her twice. At the age of 22, a medical exam showed that Beth had never had sex and had never been pregnant. These false memories were generated as a result of a strong susceptibility to suggestion (Loftus, 1997).

Repressed memories

Repressed memories occur after a traumatic event or experience in which the memory for the event is lost and can result in gaps of up to years in the memory (Burton, Westen and Kowalski, 2009). This is common in cases of sexual abuse and combat (Briere and Conte, 1993 in Burton, Westen and Kowalski, 2009). This was empirically evaluated through a study in which Williams (1994), interviewed subjects 17 years after they had been admitted to hospital for sexual abuse and found that 38% of subjects reported that they did not remember the event of sexual abuse (in Burton, Westen and Kowalski, 2009).

Amnesia

There are two types of amnesia.

Anterograde amnesia

Anterograde amnesia involves not being able to retain new memories. This usually occurs when the hippocampus or other areas of the temporal lobe are damaged. Memories before the trauma can be retrieved but new memories cannot be made (Burton, Westen and Kowalski, 2009).

Retrograde amnesia

Retrograde amnesia involves not being able to retrieve memories that were encoded for a certain time before the trauma. Memories before and after the period are able to be recalled as normal. This usually occurs in patients who have suffered a stroke or a tumour, but can also occur with emotional trauma such as depression (Burton, Westen and Kowalski, 2009).

Post traumatic stress disorder

Emotional memories that are associated with feelings of anger, guilt, fear or grief can cause enough trauma to result in post traumatic stress disorder (PTSD) (Burton, Westen and Kowalski, 2009). The symptoms of PTSD can include nightmares, flashbacks, and a distancing from the outside world (Burton, Westen and Kowalski, 2009). Memory plays a role in maintaining PTSD as emotional memories reinforce the feelings that caused the PTSD (Boals and Rubin, 2011).

How to improve memory through emotions

There are several strategies that can be used to improve memory. In term of emotion, the following theories can be applied to improve memory.

Theories

Mood state dependent retrieval

Studies have shown that emotional cues can help retrieve memories with a similar mood (Clark and Teasdale, 1985). This theory is known as the mood state retrieval effect. A study by Knight, Maines and Robinson (2002) put participants in two conditions, a sad mood or a neutral mood and asked them to remember a list of sad words. Their results found that sad words were remembered significantly more when participants were in a sad mood. They also found a difference between young adults, who showed stronger mood state dependent effects, than older adults. This theory states the certain emotions activate certain nodes in the brain where information related to that emotion is stored (Lang, Craske, Brown and Ghaneian, 2001).

Therefore, in order to enhance memory, encoding to information in a similar emotional state to when it will be retrieved will help in the recalling process.

Mood congruence effect

Mood congruence effect refers to the idea that memories will be retrieved based on the mood the person is in. For example it is easier to recall memories that have sad emotions associated with it when the person is currently in a sad mood (Knight, Maines and Robinson 2002).

Therefore to aid in remembering a certain memory, attempting to put yourself in the same mood as the memory would enhance the retrieval process.

Conclusion

Emotion and memory are two closely related concepts and studies have shown that emotions can have both a positive and negative effect on memory. The hippocampus is an essential part of the brain used when processing memories, and the amygdala and hippocampus interact to form emotional memories. The mood congruence effect and the mood state dependent retrieval theories can help in improving memory through emotional processes.

Quiz

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