Chapter 6- Long term memory- structure Flashcards
LTM function
Retaining information about the past is an important function of LTM, but it’s also involved in dynamic processes.
LTM is used to understand conversations. Working memory holds a sentence in the mind, while LTM is used to assess the meanings of the words and interpret what they mean. It provides background information, so that if another person mentions a friend’s name, you know who they’re talking about.
Serial position curve
A serial position curve is created by presenting a list of words to a participant, one after another. After the last word, participants are asked to write down all of the words that they can remember. The curve plots the percentage of participants that recalled each word versus where the word was on the list
Primacy effect
Participants are more likely to remember words presented at the beginning of the sequence. The first word gets 100% of the participant’s attention, so they likely have more time to rehearse it. This can also be explained by less proactive interference- no words came before the first word
Recency effect
Better memory for stimuli presented at the end of a sequence. This is likely because recently presented words are still in STM and are therefore easy to remember. Can be explained by less retroactive interference- nothing came after the last word.
Rundus primacy effect study
Rundus studied the primacy effect by presenting participants with lists of words and telling them to repeat any word out loud in the intervals between the words. Words presented earlier to the list were rehearsed more and were more likely to be remembered later, indicating that rehearsal creates the primacy effect
Glanzer and Cunitz recency effect study
Glanzer and Cunitz presented a list of words and after the list was presented, asked participants to count backward from 30 to prevent rehearsal. This eliminated the recency effect, suggesting that it was due to storage of the last words in the STM. With a longer delay, there was poorer recall of words. This interfered with STM maintenance
Coding
The form in which stimuli are represented in the mind. There are multiple types
Mental approach to coding
Asking how a stimulus is represented in the mind- this is what we will be focusing on in this chapter
Visual coding in STM and LTM
Coding in the form of a visual image. Remembering a visual pattern in a demonstration would be visual coding in the STM, while visualizing a person or place from the past would be coding in LTM.
Auditory coding in STM and LTM
Coding in the form of sound. In STM an example is the phonological similarity effect- people misremember two letters that sound alike. LTM- when you play a song in your head
Semantic coding
Coding in the mind in terms of meaning
Wickens semantic coding study methods
Studied semantic coding in STM. In each trial, participants were presented with words related to either fruits or professions. Participants listened to 3 words, counted backward for 15 seconds, and attempted to recall the 3 words. They did this for 4 trials with different words each time.
The goal was to create proactive interference- the decrease in memory that occurs when previously learned information interferes with learning new information.
Wickens semantic coding study results
Words from the same category were presented in all trials (either all fruits or all professions). Proactive interference is demonstrated because performance decreases with each trial. When words from a different category are presented at the last trial, performance increases. This is called release from proactive interference. Placing words into categories involves the meanings of words and participants were recalling words within 15 seconds of hearing them, so this experiment represents semantic coding in STM
Sachs semantic coding study
Studied semantic coding in LTM. Participants listened to a tape recording of a passage. Their recognition memory was measured to determine if they remembered the exact wording of the sentences or just the general meaning of the passage. It was found that specific wording was forgotten but general meaning can be remembered for a long time.
Recognition memory
The identification of a stimulus that was encountered earlier, studied by Sachs. Procedure- present a stimulus during a study period and later present the same stimulus along with others that were not presented. A multiple choice exam would be an example. This is different from recall, where participants are expected to produce the correct answer.
What type of coding is most common in STM tasks?
Auditory coding is most common due to the nature of STM tasks. For example, repeating a number over and over in your mind is an example of auditory coding.
What type of coding is most common in LTM tasks?
By reading a story a week ago, you are unlikely to remember the exact wording or what the words looked like. You probably remember the general meaning, which is semantic coding. Semantic coding is most common with LTM tasks.
Patient HM
Patient HM had his hippocampus removed to treat seizures in 1953. As a result, he was no longer able to form new long term memories. His STM was intact, but he could not transfer information to LTM. This suggests that STM and LTM are controlled by separate brain regions.
Patient KF
Patient KF suffered damage to a parietal lobe in a motorcycle accident. His LTM was intact, but he had poor STM. His digit span was reduced to 2, although 5-9 is normal. The recency effect in his serial position curve was reduced.
Double dissociation for STM and LTM
With patients KF and HM, a double dissociation could be established since they had damage to different areas of the brain and opposite memory impairments. This supports the idea that STM and LTM are caused by different mechanisms that can act independently.
Ranganath and D’Esposito hippocampus study methods
The hippocampus is crucial for LTM, but researchers wanted to determine if it could hold information for short periods of time. A sample face was presented to participants, followed by a delay, then a test face was presented and participants decided whether it matched the sample face. Some participants were assigned to the novel face condition, others were assigned to the familiar faces condition.
Ranganath and D’Esposito hippocampus study results
It was found that activity in the hippocampus increases as participants are holding novel faces in memory during the delay, but activity only changes slightly for familiar faces. These results suggest that the hippocampus is involved in maintaining novel information during short delays. The hippocampus and other medial temporal lobe structures that were once thought to be involved in only LTM also play some role in STM- these functions may not be as separated as we previously thought.
Episodic memory
Memory for experiences
Semantic memory
Memory for facts
Mental time travel
The experience of traveling back in time to reconnect with events that happened in the past. When you recall an event, you typically remember many visual details and how you felt at the time, like you are reliving the experience. According to Tulving, this is the defining characteristic of episodic memory and describes it as “self knowing” or “remembering”
Why doesn’t semantic memory involve mental time travel?
Semantic memory involves accessing knowledge about the world that isn’t necessarily tied to personal experience. When we experience semantic memory, we are are accessing things we are familiar with and know about. Tulving describes semantic memory as “knowing”, and it does not involve traveling back to the past.
Patient KC
Patient KC suffered brain damage to the hippocampus and surrounding structures in a motorcycle accident. He lost his episodic memory so he can’t relive past events, however, his semantic memory is intact. For example, he knows that his brother died 2 years ago, but does not remember personal experiences like what happened at the funeral.
Patient LP
Patient LP lost her semantic memories due to encephalitis, but her episodic memories were intact. For example, she could remember what she had done during the day, but could not remember where items were located in the store or recognize famous people.
Double dissociation for semantic and episodic memory
Patients KC and LP have opposite memory impairments, so they are an example of double dissociation for LTM. This supports the idea of separate mechanisms for semantic and episodic memory.
Brain imaging study for episodic and semantic memory
Used fMRI scans. Participants kept audio recording diaries of episodic/autobiographical memories and semantic memories from their knowledge. During the scan, researchers played the participants’ recordings. The scans showed that different areas of the brain were active during semantic and episodic memory.
How does knowledge affect experience?
Our knowledge (semantic memory) guides our experience, which in turn influences which episodic memories are formed.
Autobiographical memory
Memory for specific experiences from our life- can include both episodic and semantic components. Example- having a memory of meeting a friend at a restaurant (episodic) and remembering that the restaurant is always busy at a certain time (semantic)
Personal semantic memories
Facts associated with personal experiences
Autobiographically significant memories
Semantic memories involving personal episodes- Westmacott and Moscovitch
How can episodic memories help with recall of semantic memories?
Westmacott found that recall for the names of famous people was higher for people with more autobiographical significance. You’re more likely to remember the name of a famous singer if you’ve been to one of their concerts (episodic). In people with brain damage who have lost their episodic memory, the advantage for recall of semantic memories is absent.
Is forgetting an all or nothing process?
No. You might remember meeting a person before, but not who they are or where you’ve met them
Familiarity vs recollection
With familiarity, a person might seem familiar but you can’t recall any specific experiences involving the person. This is associated with semantic memory because it’s not associated with the circumstances under which the knowledge was acquired. Recollection is when you remember specific experiences related to the person. This is associated with episodic memory because it includes awareness of an event that happened in the past.
Remember/know procedure
Participants are presented with a stimulus they’ve seen before. They’re asked to indicate whether they know the stimulus is familiar and they remember seeing it earlier, they know the stimulus is familiar but they don’t remember seeing it, or if they don’t remember the stimulus at all. The remember response indicates episodic memory and the know response indicates semantic memory
Petrican remember/know study method
Older adults were presented with descriptions of an event and asked if they remembered (had a personal experience of the event or remembered hearing about it on TV), knew (if they were familiar but had no personal experiences) or if they didn’t remember the event at all.
Petrican remember/know study results
For events that occurred 40-50 years ago, remember responses decreased much more than know responses (from 10 years ago events). This illustrates semanticization of remote memories- loss of episodic detail for memories of long ago events.
Semanticization of remote memories
Loss of episodic detail for memories of long ago events. You generally remember much more about what you did today than what you did a week ago. You might remember semantic information from middle school, but you likely have no episodic memory of the classroom you were in when you learned it, for example.
Constructive episodic simulation hypothesis
States that episodic memories are extracted and recombined to construct simulations of future events.
How does memory play a role in imagining the future?
There seems to be a connection between remembering the past and imagining the future- patient KC, who lost his episodic memory, also lost his ability to imagine personal events that could happen in the future.
McDermott imagining future events study
Participants were asked to remember an event from the past or imagine an event that might happen in the future. Participants were asked to report they were seeing their event in a first or third person perspective. It was concluded that there are likely common processes involved in both situations.
Why is it important to be able to imagine the future?
When the future becomes the present, we need to be able to act effectively. The main role of episodic memory may be to allow people to simulate possible future scenarios in order to anticipate future needs and guide future behavior. Similarly, mind wandering can be an adaptive process and play a role in imagining the future and retrieving autobiographical memories.
Explicit memories
Also called declarative- memories we are aware of. Includes episodic and semantic memory
Implicit memories
Memories where learning from experience is not accompanied by conscious remembering. Includes procedural memory, priming, and conditioning
Procedural memory
Also called skill memory, memory for doing things that usually involve learned skills. People perform skills without being consciously aware of how to do them. Some cognitive skills, like knowing grammar rules for a language, also count as procedural memory.
Evidence for the implicit nature of procedural memory
Although HM could not form new episodic memories, he could improve at a procedural task (mirror tracing task). Each day, he improved at the task although he had no memory of doing it before. He also could form spatial memories, like memory for the layout of his house. People with amnesia can become experts at tasks they don’t remember training in.
Expert induced amnesia
Well learned procedural memories do not require attention. These actions occur automatically, like an expert pianist playing music without looking at their fingers
How are procedural memory and semantic memory connected?
Patient LSJ lost the ability to remember past events in her life and her knowledge of the world (semantic memory) due to encephalitis. However, she could answer questions related to things that involved procedural memory. This suggests that knowledge about specific fields (semantic memory) is linked to the ability to carry out skills (procedural memory).
Priming
When the presentation of one stimulus (the priming stimulus) changes the way a person responds to another stimulus (the test stimulus).
Repetition priming
Occurs when the test stimulus is the same as or resembles the priming stimulus. Seeing “bird” earlier in an experiment may cause you to respond more quickly to the word later on, even if you don’t remember seeing it- therefore, this type of priming is called implicit memory
Graf implicit memory study
Participants with and without amnesia were given explicit and implicit memory tasks (memory for words and word completion). For the explicit memory task, patients were asked to rate whether they liked or disliked the words to prevent rehearsal. Testing patients with amnesia ensured they would not remember the priming stimulus. It was found that participants with amnesia had poor explicit memory, but their implicit memory was as good as the controls.
Propaganda effect
Participants are more likely to rate statements they had read or heard as true just because they’ve been exposed to them before. Involves implicit memory because people may not be aware that they’ve heard the statement before. They might even have thought it was false when they first heard it (illusory truth effect)
Classical conditioning
Occurs when two stimuli are paired: a neutral stimulus that initially does not result in a response and a conditioning stimulus that does result in a response. Example- pairing a tone with a puff of air will eventually cause the person to blink even in the absence of the puff of air when the tone plays. This is implicit memory because people can forget about the original pairing of the stimuli
Serial position effect
The tendency for some words to be more likely to be recalled. The accuracy in recall differs across the original positions in a list
Decay
Forgetting occurs due to the passage of time (fading)
Interference
Forgetting occurs due to the presentation of other material (in the case of the Glazner study, it was the backwards counting task). There are two types.
Proactive interference
Interference caused by earlier events, or past events. Example- you have trouble remembering where you parked today
due to interference from where you parked last Monday. Or, already knowing Spanish interferes with your ability to learn Italian.
Retroactive interference
Memory for an event is impaired by later events, or recent events. Example- trouble remembering where you parked last Monday because of where you parked today.
What types of memories cause more interference?
Not all memories interfere with each other equally. Memories that are similar will interfere with each other more than two dissimilar memories. Ex- monologues from Hamlet and Macbeth (similar) will cause more interference than those from Macbeth and the Wizard of Oz (dissimilar)
Release from proactive interference
The buildup in PI in the Wickens study is due to the similarity of the lists. Semantically similar lists compete for representational space more than
semantically dissimilar lists- more similar = more proactive interference. If the category of stimuli changes, you are “released” from the interference
and recall performance improves. Extent that you are “released” again influenced by semantic similarity
Hippocampus
Hippocampus is one of the most important brain areas for LTM, it’s located in the medial temporal lobe
Flashbulb memory
An extremely vivid autobiographical memory, typically not very accurate
Amnesia
The catastrophic loss of memory or
memory abilities caused by brain damage or disease. Many of the components of the taxonomy of long-term memory have come from studying patients with amnesia
Retrograde Amnesia
The loss of memory for events before a brain injury. More disruption for more recent memory, less disruption for older memory. Ex- can remember childhood best friend, but not your college best friend.
Anterograde Amnesia
The disruption of memory for events occurring after brain injury. Acquiring new long-term memories
Gabrieli visual priming study
Tested visual priming effects (patterns). Used dot patterns. Recognition- participants were used to indicate if a pattern is new or old (explicit memory). They were primed using dot-line patterns (implicit memory). HM had much worse explicit recall than controls, but HM still exhibited the priming effect.
