Long-term memory - summary of chapter 5 of Cognitive Psychology by Gilhooly, K & Lyddy, F, M

Cognitive Psychology
Chapter 5
Long-term memory

Three important aspects of long-term memory processes:

• Long-term memory processes are not disturbed throughout the brain. Damage to particular areas within the temporal lobes will cause profound long-term memory loss. Particular brain regions are responsible for long-term memory function.
• Long-term memory encompasses a number of different abilities and some learning may be possible after damage to the system.
• memory is separable form language, perceptual and other cognitive functions.

Memory and amnesia

Amnesia revers to the amnesic syndrome. A pattern of memory loss characterized by impaired long-term memory and spared short-term memory.
General characteristics:

• Short-term memory is intact
• Memory for language, and concepts is largely intact.
• There is a severe and lasting anterograde amnesia (memory for events after the onset of the amnesia will be impaired).
• There will be a retrograde amnesia, of variable extend. The patient will have loss of memory for events prior tot the onset of amnesia.
• Skill learning, conditioning and priming will be unaffected. The patient will also be able to engage in skills acquired prior to the onset of amnesia.

Ribot’s law:
Recently formed memories are more susceptible to impairment that are older memories.
Wechsler Memory scale: a widely used neurocognitive assessment that measures visual memory, auditory memory and working memory.

Causes of amnesia include effects of brain surgery., infections, head injuries or stroke, conditions such as Korsakoff’s syndrome, and injury.

Korsakoff’s syndrome: brain dame related to thiamine (vitamin B1) deficiency. It generally occurs following prolonged alcohol abuse in per-disposed individuals. It is associated with damage to the thalamic, mamillary body and frontal brain areas.

In patients with amnesia, language and concepts are generally intact. The person can answer a question and can understand what a particular object is, and what it does.
However, most of our knowledge about the world and about language is laid down early in life.
One of the problems with testing patients with amnesia is being sure that the information was stored in memory in the first place.

Long-term potentiation (LTP): a mechanism that is inferred from animal models. LTP is a long-lasting increase in the strength of synapses that occurs with repeated stimulation.
Long-term depression (LTD) or depotentiation: a weakening of synapses.

The structure of LTM

There are different kinds of LTM.

When we call something in mind, we are using short-term memory, but all of the memories that we have, whether we are currently thinking of them or not, are stored in LTM.

Multiple memory systems model

LTM consists of separate components. The precise number of components, their exact nature and the relationship between them continue to be debated.

Verbal learning: the area of experimental psychology concerned with how we learn and remember language-based items.

Distinction in LTM between:

• Non-declarative (or implicit) memory
  Memory that is not accessed consciously and that we are not able to report verbally. In includes memory which benefits form previous experience but without our awareness of that experience.
• Declarative (explicit) memory
  Involves conscious recollection of memories such as events, facts, people and places
  Know that opposed by know how.

Free recall: when participants in a task recall the information in any order, without hints or clues to recall.
Cued recall: when a hint or cue is given to task participants to aid recall.
Recognition: when a task participant must verify if an item is a target.

In almost all cases of amnesia, difficulties with declarative memory are noted, while non-declarative memory was still intact.
Learning in amnesia can extend to a wide range of types of task. These task have in common that they do not require explicit memory, they do not require retrieval of the original learning episode.

Endel Tulving. A tri-partite (three part) model of LTM.
Distinction:

• (Declarative) episodic memory
  Memory for events, experiences and episodes
  Relies on temporal context for recall.
• -(Declarative) semantic memory
  Memory for facts and knowledge about the world
  Doesn’t rely on temporal context for recall.
• Non-declarative memory

Not everyone agree s that there is a clear-cut distinction between episodic and semantic memory.

• Not all information can be reliably classified as either episodic or semantic.
• The distinction blurs by autobiographical memory

Non-declarative memory

Much of memory occurs without our conscious awareness.
Non-declarative memory is demonstrated on a wide range of tasks, including classical conditioning, motor skill learning, and priming.

Skill learning

Procedural memory: a type of non-declarative memory involving memory for how to perform skills and actions.
Closely associated with motor performance but cognitive skills and some perceptual learning skills are also aspects of procedural memory.
Such knowledge is generally acquired over time through practice and can become automatic. Sometimes when we concentrate our thoughts on a skill we can disrupt the processes involved and performance can suffer.

Procedural memory is generally preserved in patients with amnesia.

Habit learning

Habit learning refers to memory acquired over time through repeated associations between stimuli and responses.

Poorly understood in humans because of the difficulty in eliminating the influence of conscious memory on the learning situation.

Probabilistic classification learning: involves learning a set of associations that cannot be readily memorized, and information from across many trials must be used to complete the task.
Used to investigate habit learning.

Repetition priming

Priming: an implicit memory effect whereby exposure to a stimulus affects a subsequent response.
The facilitatory effect of previous exposure to a stimulus on the subsequent processing of that stimulus or a related stimulus.
Performance may be faster, accuracy may be improved or there may be a bias towards a particular stimulus.
Priming can be conceptual or perceptual, depending on whether it is the stimulus form or the stimulus meaning that is salient.

Conceptual priming tasks:

• Category exemplar tasks: those where participants are given category names one by one and are asked to generate exemplars for each. Some categories will have been encountered during an earlier stage.
• Word association.

Most repetition priming tasks do nor require declarative memory processes and performance is unimpaired in patients with amnesia.

Declarative memory

Episodic memory

Episodic memory is the system within LTM that allows us to remember our past experiences. It enables us to consciously re-experience past events.
Three key properties:

• It is associated with our subjective sense of time that allows us to engage in ‘mental time travel’.
• There is a connection to the self. Mental time travel requires a traveler.
• Mental time travel is associated with a special kind of conscious awareness called autonoetic (self-knowing) consciousness. (allows humans to use memory to relive past events and imagine ourselves in the future, from a self-perspective.)

Episodic memory:

• Evolved recently
• Develops late
• Deteriorates early
• Is vulnerable to disruption by brain damage
• Is unique to humans
• Evolved from semantic memory

Memories are constructed anew when they are called to mind, and can differ from the original event, and with each recall of the event. Memory is a constructive process.

Memory as a (re)constructive process.

The concepts of ‘mental time travel’ neatly describes the experience of remembering or reminiscing.
Episodic memory is not an exact copy. Memory is constructive and when we recall our past experiences, we reconstruct the event in our minds, using information gained before, after and at the time of the event or episode itself.

Memory is reconstructive and not a passively recalled record of events. It can be open to modification and error.

The role of schema in remembering past events.
Schema; an active organization of past reactions or past experiences.
Recall involves condensation, elaboration and invention. These all very often involve the mingling of materials belonging originally to different schemata.
Schemas are organized memory structures that allow us to apply past experience to novel situations so as to guide behavior.
They demonstrate the interaction between semantic and episodic memory.
Schemas produce expectations that reduce the ambiguity of new situations, however, these expectations can sometimes lead to erroneous judgments.

The cognitive system focuses resources on the past only insofar as it contributes to thinking about the future.
The adaptive function of memory is to allow us to use past experiences in order to adapt our behavior so as to deal more effectively with the present and future events.
Focus on past performance only serves a purpose if it influences future behavior, if you can learn from the experience and apply it to a future examination or similar experience.
The adaptive function of episodic memory lies in its potential for imagining of future events.
Prospective memory: memory that allows us to keep track of plans and carry out intended actions. Remember to remember.

Prospective memory and imagining future events

Travel forward in time.
This use of memory is an essential component of forward planning.
Prospective memory. Memory for intended actions, actions that are to be performed at some future time.

Individuals with amnesia lost their prospective memory and find it difficult to conceptualize a personal future.

The most common prospective memory failure involves neglecting to carry out an actions at the appointed time.
Prospective memory lapses often involve a failure to interrupt habitual routines.
They differ from actions slips (an action being completed when it was not intended)
Prospective memory is normally highly effective.
Unlike other kinds of memory, prospective memory is not necessarily triggered or cued by an obvious external event. Rather retrieval in prospective memory is self-initiated.

Two kinds of prospective memory tasks:

• Event-based
  May be triggered by a particular cue.
• Time based
  A specific time prompts action.
  Two kinds of intention.
  • Pulses: involve intentions that are time-locked. Associated with better recall. And are more likely to be facilitated by means of memory aid (like making a note in a diary)
  • Steps: intentions that have a wider time frame in which they can occur.

Neuroscientific evidence supports substantial overlap between brain areas engaged when thinking about the past and when imagining the future.
Shared activity is evident in prefrontal cortex and medial temporal lobe regions, including hippocampus and pararhippocampal gyrus.

Autobigraphical memory

Most of the day-to-day events that we will remember over a short period of time disappear from memory quickly.
It would not be useful for us to remember the banal details of everyday experience. We remember what is useful, salient or distinctive and other details are lost.
Episodic memories become embedded in the broader conceptual system, along with semantic memories, autobiographical memories are formed.
These are our memories for both personal episodic information and personal semantic information.
Personal episodic information includes personally experienced events, from everyday activities to once-in-a-lifetime experiences.
Personal semantic information consists of facts about ourselves.

Autobiographical memory involves personal experience and it is closely associated with the self.
Even these highly personal memories are not free from bias.
Memory is a reconstructive process, and when we recall life events, we reconstruct or interpret the memory ‘record’ rather than play it back passively.

False memories: inaccurate recollections of events that did not occur, or distortions of events that did occur.
Imagination inflation: strengthening of a false memory through repeated retrieval. Imagining false events increases the likelihood that they well be ‘recalled’.

Demand characteristics: the aspects of a research study which convey the hypothesis or aims to the participants and may thereby shape performance.

Déjà vu: a type op illusion of autobiographical memory: knowledge that a situation could not have been experienced, combined with the feeling that it has.
Three possible mechanisms:

• Split perception. We get a brief glimpse of a visual scene before becoming fully aware of the scene
• Implicit memory: we have already experienced the scene or part thereof but it has been stored such that only a feeling of familiarity is elicited when we re-encounter it.
• The notion of gestalt familiarity: that overall configuration of the present scene closely resembles a scene that we have have encountered in the past. Though the specifics are different.

Jamais vu: then something familiar momentarily seems unfamiliar.
Presque vu: the feeling that we are about to experience a moment of insight.

Semantic memory

Our store of general knowledge about the world, the people in it, as well as facts about ourselves.
It includes our knowledge of facts, language and concepts. And all the knowledge we need in order to use language.
General knowledge.

People who share the same language and culture have much in common in terms of semantic memory.
Semantic memory also contains individual knowledge.

Semantic memory differs from episodic memory in a number of ways:

• Metamemory: (the ability to monitor and inspect the content of memory. It allows us to know whether we know something). It differs in the two.

Semantic memory remains intact and available even after a brain injury affecting memory.
Once knowledge had stabilized in semantic memory, it remains resistant to forgetting over potentially a very long period.
Permastore: involves the long-term retention of content that has been acquired and relearned over a period of time. Even if rarely used after.
Similar for personal semantic memory.