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Chapter 6: Long-Term Memory – Structure
DISTINGUISHING BTWN LTM & STM
• Korsakoff’s Syndrome: Condition caused by prolonged deficiency of vitamin B1, usually as a result of
chronic alcoholism. This deficiency leads to destruction of frontal and temporal lobes, causing severe
• Anterograde Amnesia: Loss of ability to retain new knowledge or memories – unable to recognize
people he has just met, follow a story in a book. Retrograde Amnesia: Loss of memory for events that
have happened in the past
• Long-Term Memory (LTM): System responsible for storing large amounts of info for long periods of
time, an “archive” about past events in our lives. STM is to RAM, working memory is to CPU, and LTM is
to hard drive.
Long-Term & Short-Term Processes
• Recollections in LTM stretch from a few moments ago to years to decades back (long duration, large
capacity). Recent memories tend to be more detailed, while with time these details fade with the passage
of time and accumulation of other experiences
• LTM not only retains information about the past, it operates dynamically to interact with working
memory to create our ongoing experience; wealth of background information we are constantly
consulting as we use working memory to process what is happening at a particular moment.
• E.g. Tony’s friend Sarah says, “Jim and I saw the new James Bond movie last night” Jim is the new
guy Sarah met a month ago + Sarah is a big James Bond fan + I saw that movie, it was good.
Serial Position Curve
• Murdoch (1962): Subject hears a list of stimulus words being read (at 1 word every 2 seconds), and at
the end must write down all the words heard, in any order.
• Serial Position Curve: Percentage recall for each word against the word’s position in the list, e.g. how
many words were remembered from the first 5 entries, middle 5, and last 5?
• Memory is better for beginning and ends words than the middle. The primacy effect may exist
because subjects have more time to rehearse these words and transfer them to LTM, particularly at the
beginning when no other words are being attended to; as additional words are presented, less rehearsal
is possible for later words
• Rundus (1971): Presented list of 20 words at 1 word every 5 seconds, later asked to recall words. To
some subjects, he asked them to repeat words out loud during the 5-second interval between words, but
not told which ones to repeat. Indeed, subjects rehearsed words presented early in the list much more,
which they were more likely to remember later.
• Recency effect may occur since the most
recently presented words are still in the STM/WM.
• Glanzer & Cunitz (1966): Measure recall with
subjects having to count backwards for 30
seconds between having heard the last word on
the list and recalling (attention and WM
occupied). This prevented rehearsal and allowed
time for info to be lost from STM, such that the
recency effect was eliminated.
Coding in Long-Term Memory Page 148-167, 20 pages Page 2 of 6
• Auditory, visual, and semantic coding can occur for STM. LTM can also involve each of these types,
such as visual coding to recognize someone’s face, auditory coding for someone’s voice, and semantic
coding for remembering the meaning of an event in the past.
• Semantic coding is the predominant type of LTM coding.
• Sachs (1967): Participants listen to a tape recording of a message, then measure recognition memory
with identification of a stimulus that was encountered earlier – specifically the exact wording of sentences
in the passage, or the general meaning of the passage.
• E.g. List of words including “house”, then present series of words including “house” and other words
such as “table”. The subject must answer “yes” if the word was presented previously and “no” if it was not
– this is different from recall where one would have to produce the item to be recalled.
• Original sentence “He sent a letter about it to Galileo, the great Italian scientist” with option 1 being
identical, option 2 as “Galileo, the great Italian scientist, sent him a letter about it” and option 3 as “He
sent Galileo, the great Italian scientist, a letter about it.”
• Most correctly identify 1 as identical and 2 as changed, but misidentified 3 as matching. The subjects
remembered the sentence’s meaning instead of its exact wording.
Locating Short & Long-Term Memory in the Brain
• Experiments that compare where STM/WM and LTM are represented in the brain – there is both
separation and overlap in brain regions
• Dissociations can be used to draw conclusions from case studies of brain-damaged patients, including
differentiating between STM and LTM where one function is affected but the other is spared. With two
cases of opposite effects, a double dissociation can indicate that STM and LTM operate independently
and are served by different mechanisms.
• H.M. underwent lobectomy of the hippocampi, amygdala, and other structures to relieve seizures. He
experienced retrograde and anterograde amnesia (LTM), but had normal LTM.
• Clive Wearing similarly has functioning STM for the most recent 30 seconds, but is unable to form new
• Patient K.F. with opposite problem, suffered a stroke to the left parietal lobe. With a damaged
phonological loop, normal LTM but poor STM as shown by a reduced digit span – span of 1 rather than
between 5 and 8 digits. In addition, recency effect in serial position curve is reduced.
• Talmi (2005): Activation of different areas of the brain for STM and LTM tasks with fMRI. First presented
list of words to subjects, but instead of asking to recall, they presented a single “probe” word that was
either from near the beginning of the list (LTM), near the end (STM), or a novel word. The subject had to
indicate whether the word had been presented before.
• Probe words from the beginning of the list (LTM) activated brain areas associated with both LTM and
STM – LTM to remember and transfer to STM during recall. In contrast, probe words from the end of the
list only activated areas associated with STM. Accessing LTM requires activation of the STM/WM to be
brought to awareness!
Types of Long-Term Memory
• Explicit Memory: Conscious or declarative memory. It consists of episodic memory for personal
experiences and semantic memory with stored knowledge for facts. E.g. Going to cognitive psychology
class memory, versus facts about theories of attention. Include recall and recognition tasks.
• Implicit Memory: Non-declarative or unconscious memory. It consists of memories used without
awareness, such that these cannot be reported. Includes priming with change in response to a stimulus
caused by previous presentation of the same or a similar stimulus, such as recognizing familiar words.
Also includes procedural or “skill” memory for doing things, such as typing. Finally, includes classical Page 148-167, 20 pages Page 3 of6
conditioning where an initially neutral stimulus is paired with another to result in the neutral stimulus
taking on new properties
EPISODIC & SEMANTIC MEMORY = EXPLICIT
Distinguishing between Episodic & Semantic Memory
• Distinguishing based on type of information remembered: events for episodic, facts for semantic.
• Tulving (1985): Episodic memory involves mental time travel, to reconnect with events that happened
in the past such as a trip to London. This experience is about self-knowing or remembering with
putting oneself back in a situation – however, this does not guarantee the memory is accurate.
• Semantic memory involves accessing knowledge about the world that need not be tied to a personal
experience, such as facts, vocabulary, and concepts. Semantic memory is about knowing and does not
involve mental time travel – e.g. can remember population size of London or historical facts, but not
where I learned these things.
The Separation of Episodic & Semantic Memory
• Evidence that these two types of LTM are served by different mechanisms
• K.C. at age of 30 suffered severe damage to his hippocampus, and lost his episodic memory – unable
to relive any of the events of his past, but he knows that certain things occurred (semantic remains). For
example, he is aware his brother died two years ago, but cannot recall its circumstances or where he
was when he heard about it.
• The opposite scenario occurred to an Italian woman who suffered encephalitis. She experienced
difficulty recognizing familiar people, and remembering the meaning of words on the shopping list or
where things were located in a grocery store – all semantic memories destroyed. However, she could
remember events in her life, such as what happened last week.
• There is a double dissociation between episodic and semantic memory, using different
• However, interpretation of neuropsychological cases is tricky since the extent of brain damage often
differs from patient to patient, and the method of testing patients may differ between studies.
Brain Imaging Evidence
• Levine (2004): Subjects keep diaries on audiotape describing everyday personal events and facts
drawn from semantic knowledge. When the subjects listen back to these tapes in an MRI scanner, the
recordings of everyday events elicited detailed episodic autobiographical memories, while the factual
recordings induced semantic memories.
• Areas activated