Long-term memory (LTM) is explored, emphasizing both the division into different types and the interaction between them.
Different types of memory:
Episodic memory: Specific experiences from the past.
Semantic memory: Memory for facts.
Procedural memory: Memory for how to carry out physical actions.
The study of different types of memory relies on:
Behavioral experiments.
Neuropsychological studies.
Brain imaging experiments.
Explicit and implicit memory are referred to as declarative and non-declarative memory respectively.
Comparing Short-Term and Long-Term Memory Processes
Long-term memory (LTM) is responsible for storing information for long periods.
LTM is an archive of past events and learned knowledge, stretching from moments ago to as far back as we can remember.
LTM has a longer duration and a larger, possibly unlimited, capacity compared to STM.
STM is more than a temporary storage; it involves dynamic processes, leading to the concept of working memory.
LTM also involves dynamic aspects, interacting with working memory to create our ongoing experience.
Example: Oskar understanding Sarah's statement about seeing a James Bond movie. Working memory holds the statement, while LTM accesses word meanings and background information about movies and Sarah.
LTM provides an archive for past events and background information for current experiences.
Serial Position Curve
The interplay between STM/WM and LTM is fundamental.
The serial position curve indicates better memory for words at the beginning and end of a list compared to the middle.
Primacy effect: Better memory for words at the beginning, because participants have time to rehearse and transfer them to LTM.
The first word receives 100% of the participant's attention and as additional words are presented, less rehearsal is possible for later words.
Rundus,1971
Recency effect: Better memory for words at the end, because these words are still in STM.
When a short delay between the presented list and the recall period is introduced (for example 30 seconds) then the recency effect was found to disappear.
Glanzer & Cunitz, 1966
The serial position curve illustrates the interaction of STM and LTM.
Coding in Short-Term and Long-Term Memory
Coding refers to the form in which stimuli are represented.
Physiological approach: How stimuli are represented by neuron firing.
Mental approach: How stimuli are represented in the mind.
Types of coding to be compared:
Visual coding (visual image).
Auditory coding (sound).
Semantic coding (meaning).
Visual Coding
Short-Term Memory: Visual coding is used in the short-term memory when asked to remember the visual pattern.
Long-Term Memory: Recalling the view from a holiday home or a friend's face.
Auditory Coding
Short-Term Memory: Phonological similarity effect, where similar-sounding letters are confused.
Long-Term Memory: "Playing" a song in your head or "hearing" the next song on a playlist during the silence between tracks.
Semantic Coding
Semantic coding primarily happens in long-term memory, since we often do not seem to remember the visual or acoustic details of a story/film, but only the general plot.
Wickens, Dalezman, and Eggemeier (1976) study shows semantic coding in short-term memory using proactive interference.
Proactive interference: Previously learned information interferes with learning new information.
In the Wickens et al. experiment:
Participants presented with words from categories (fruits or professions).
Proactive interference occurs when words from the same category are presented in a series of trials.
Release from proactive interference occurs when the category changes, improving performance.
The proactive interference for the Fruits group can be attributed to the meanings of the words.
Release from proactive interference indicates semantic coding in short-term memory.
Sachs (1967) recognition study confirms semantic coding in LTM.
Participants remember the general meaning of sentences but not the exact wording.
Comparing Coding in Short-Term and Long-Term Memory
Information can be represented visually, auditorily, and semantically in both STM and LTM.
Auditory coding predominates in STM tasks.
Semantic coding predominates in LTM tasks because understanding is emphasized above literal repetition.
Locating Memory in the Brain
The prefrontal cortex, parietal cortex, and visual/temporal cortex are involved in working memory (Figure 5.28).
Neuropsychological studies provide the strongest evidence for the separation of STM and LTM in the brain.
Henry Molaison (H.M.) case study: Removal of medial temporal lobe (including the hippocampus) eliminated his ability to form new long-term memories, while short-term memory remained intact.
Brain imaging studies support the idea that the hippocampus is crucial for forming new long-term memories.
Ranganath and D'Esposito (2001) examined the role of the hippocampus in holding information for short periods.
Hippocampal activity increased when holding novel faces in memory during short delays.
The hippocampus and medial temporal lobe structures play a role in both short-term and long-term memory.
Functions are not as disconnected as previously thought, especially for tasks involving novel stimuli.
Episodic and Semantic Memory
Episodic and semantic memory are both part of explicit/declarative memory.
Episodic memory: Memory for specific experiences in the past.
Semantic memory: Memory for facts.
(1) the type of experience associated with episodic and semantic memories;
(2) how brain damage affects each one;
(3) differential effects of aging; and
(4) the fMRI responses to each one.
Distinctions Between Episodic and Semantic Memory
Episodic memory involves mental time travel – reliving past events.
Mental time travel is self-knowing or remembering.
Episodic memory also refers to what is measured in laboratory tasks that require conscious recall or recognition of previously presented material
Semantic memory involves accessing general knowledge about the world, not tied to a specific personal experience or encoding/study period.
Knowing without mental time travel.
Semantic memories are created by a process in which episodic memories are being 'stripped' from their original context and become abstracted or 'semanticized' with time and over multiple repetitions.
Neuropsychology Evidence
K.C. lost episodic memory due to damage to the hippocampus and surrounding structures but retained semantic memory.
An Italian woman lost semantic memory due to encephalitis but retained episodic memory.
These cases demonstrate a double dissociation between episodic and semantic memory.
Double dissociation: support the idea that memory for these two different types information probably involves different mechanisms.
Memory and Aging
Semantic memory increases until about 60-65 years of age, while implicit or non-declarative memory shows little change from early to late adulthood.
Episodic memory deteriorates rapidly with old age, especially when measured with a free recall instead of recognition test.
Episodic memory has been found to remain stable between 35-60 years of age and then to deteriorate quickly.
Semantic memory still increases between 35-60 and then also declines, but at a much slower rate.
The age-related decline in episodic memory has been associated with structural and functional changes in the brain, including those involving the prefrontal cortex and the medial temporal lobe containing the hippocampus
Brain Imaging Evidence
Levine et al. (2004) used brain imaging to study episodic and semantic memory.
Everyday events elicited detailed episodic autobiographical memories, while factual knowledge reminded people of semantic facts.
Knowledge guides experience which influences episodic memories that follow.
Autobiographical Memory
Autobiographical memory contains both episodic and semantic components (personal semantic memories).
Semantic components of this description are called personal semantic memories because they are facts associated with personal experiences.
Westmacott and Moskovitch (2003) - People's knowledge about public figures, such as actors, singers and politicians, can include both semantic and episodic components.
Autobiographically significant semantic memories.
Recall was better for names of people who had higher autobiographical significance.
Forgetting
Short-term memory lasts only about 15-20 seconds.
With time, memories fade and details about specific experiences get forgotten.
Familiarity is associated with semantic memory.
Recollection is associated with episodic memory.
Measure using the remember/know procedure.
Petrican et al. (2010) experiment shows that remember responses decreased much more than know responses by measuring memory for public events changed over time
The semanticization of remote memories-loss of episodic detail for memories of long-ago events.
The knowledge that makes up your semantic memories is initially attained through personal experiences that are the basis of episodic memories, but your memory for these experiences often fades, and only semantic memory remains..
Internet and Mobile Technology on Cognition, Attention and Memory
The main question often asked in studies is whether the internet makes semantic memory obsolete?
Procedural Memory, Priming, and Conditioning
Explicit memories are memories we are aware of and can talk about (or "declare").
Implicit memory occurs when learning from experience is not accompanied by conscious remembering.
Procedural Memory
Procedural memory is also called skill memory because it is memory for doing things that usually involve learned skills.
Implicit nature of procedural memory demonstrated in amnesic patients who can master new skills without remembering the practice.
Motor skills and cognitive skills both qualify as procedural memory.
Priming
Priming: Presentation of one stimulus (priming stimulus) changes the way a person responds to another stimulus (test stimulus).
Repetition priming: The test stimulus is the same as, or resembles, the priming stimulus.
Lexical decision task for example.
Repetition priming is called implicit memory because the priming effect can occur even though participants may not consciously remember the original presentation of the priming stimuli.
Graf, Shimamura and Squire (1985) measured three groups of participants: (1) amnesic patients with a condition called Korsakoff's syndrome, (2) patients without amnesia who were under treatment for alcoholism; and (3) patients without amnesia who had no history of alcoholism.
Word completion tests contained the first three letters of the 10 words that the participants had seen earlier (experimental condition), plus the first three letters of 10 words they had not seen earlier (control condition).
Implicit memory is presumed to be present when in the experimental condition, comparatively many word stems are completed with the words that had been presented before (in our example thus to carpet and volume).
In the recall experiment, the amnesic patients recalled fewer words than the two control groups.
Reducing Chances of Remembering Priming Stimulus
Researchers have used a number of methods to reduce the chances that a person in a priming experiment will remember the original presentation of the priming stimulus.
Perfect and Askew (1994) had participants scan articles in a magazine, and they gave higher ratings to a number of advertisements that they had been exposed to than to other advertisements that they had never seen.
This result qualifies as an effect of implicit memory because less than 3 advertisements of the total were recognized.
Propaganda effect: Participants are more likely to rate statements they have read or heard before as being true.
Implies that propaganda effect even occurs when people are not aware that they have heard or seen a statement before, and may even have thought it was false when they first heard it.
Classical Conditioning
Classical conditioning occurs when a neutral stimulus is paired with a conditioning stimulus that results in a response.
After a number of pairings with the puff of air, the person blinks in response to the tone.
This is implicit memory because it can occur even if the person has forgotten about the original pairing of the tone and the air puff.
Classical conditioning in daily live occurs when, for example, you automatically reach for your mobile phone when you hear a familiar notification chime.