Lecture 18 - Types of Knowledge/Memory Flashcards
semantic memory
your knowledge base: the things/facts that you know
version of LTM
(i.e. memory for
categorical, factual information)
episodic memory
the events that you remember
things that happened to you or things that made an impression
procedural memory
skills
things you can do/know how to do
declarative memory
things you can state or verbalize
implicit memory
the things that you’re not aware that you know
stuff that you can do but you’re not consciously aware that you can do
explicit memory
stuff that you’re conscious of (when you recall something
Semantic memory is thought to
have three primary characteristics:
1) It is organized by content
2) It allows us to make inferences
3) Semantic info generalizes beyond a single episode
Semantic memory is organized by content
Similar concepts are more likely to cue one-another through association. [lexical decision task]
e.g. “doctor and nurse” are content that share alot of context so they’re more tightly associated than “doctor and table”
Semantic memory allows us to make inferences
There appears to be a logical, hierarchical order to the
categories (to LTM).
Semantic info generalizes
Information is not tied to a single instance but rather is more reflective of all the things that have happened
One way of testing semantic information is
using a lexical decision task (Meyer &
Schvaneveldt, 1971).
trying to decide: is something a word or not?
• A string of letters is presented (e.g. PRINTER or
PROGER) and you judge it is a word or nonword.
- The letter string is PRECEDED by a related or unrelated word.
- Related primes (e.g. nurse –> DOCTOR) were faster than unrelated primes (e.g. butter –> DOCTOR).
• What does the speed of retrieval say about the
internal structure of memory?
priming
sets up activation in a network
feedforward activation of some concept (nurse) that goes to activate other related concepts
Semantic memory is thought to be structured and allows
inferences.
- Is a canary a bird?
- Is a canary made of molecules?
• The first question requires retrieval from long-term memory; the second question is likely novel and requires an
inference or other knowledge - semantic relatedness (and takes a bit longer):
canary -> bird -> animal -> physical object -> made of
molecules
• The speed of retrieval and nature of the inferences suggests a possible structure to long-term memory.
The speed of retrieval (taking longer for novel objects) and nature of the inferences suggests
a possible structure to long-term memory.
what kind of structure does memory follow?
hierarchical
Collins & Quillian (1969) proposed a hierarchical model of long-term memory.
very much like a computer model: digital conception of what knowledge would ideally look like
an attempt to use logical operators
• Nodes in the model are concepts or ideas (e.g. bird, animal).
• Links are labeled (“is-a” or “has-part”) and directed. Subordinate categories
point to superordinate categories.
• Activation tags help verify inferences in the network.
− Canary is yellow (faster)
− Canary has skin (slower)
Nodes in hierarchal model
not just words but concepts
are concepts or ideas (e.g. bird, animal).
each node has links to other elements
Links in hierarchal model
are labeled (“is-a” or “has-part”) and directed. Subordinate categories point to superordinate categories.
links point in a direction, natural flow
sometimes they point to a property or the relationship between different nodes
“is-a” link
the canary “is-a” bird, a bird “is-a” animal
the way things are organized in the structure
“has-part” link
a bird has wings, has feathers, other qualities that that node (concept has)
activation tags
help verify inferences in the network.
e.g. “can sing”, “is yellow”
− Canary is yellow (immediate activation of has-part link, faster)
− Canary has skin (slower)
- not something you would really tie to the concept of canary - subordinate category, so not immediate activation because memory has to work for it
The hierarchical model has three main criticisms.
• Problem 1: the typicality effect.
• Problem 2: Violations of the
hierarchical order.
• Problem 3: How do you respond with “False”?
the typicality effect
• People verify (yes/no, true/false) typical instances of a category faster than atypical
examples.
− typical: Is a canary a bird? (faster)
− atypical:Is a penguin a bird? (slower)
by a hierarchical model there should be just one link from canary to bird because they both relate to the same class and one link from penguin to bird
- there's no reason for the penguin to be slower based solely on this model (should be the same number of steps and the same amount of time)
Violations of the
hierarchical order.
• Some activations seem to go around the hierarchical order.
- you don’t follow nice straight path, INSTEAD take shortcuts
− “A canary is a bird?” is faster
than “A canary is an animal?”
(okay) .
− “A penguin is a bird?” response is slower than “A penguin is an animal?” (problem).
–> should go in a strict hierarchy from penguin to bird to animal (so in effect, it should take longer to take to animal)
How do you respond with “False”?
• Speed to respond “false” should only depend on “is-a” and “has-part” links (the number of links you have to go through).
However, people also seem to
consider similarities.
− “A bat is a bird?” gets a slower
false response.
− “A bat is a plant?” gets a faster
false response.
− Bat => Mammal => Chordata =>
Animal
• This is called the relatedness effect.
we’re not computers! we don’t go through those logical inferences
to fix the “typicality effect” problem
• To fix this, some links need to be stronger than others.
- you’re so used to canaries (more exposure) than penguins so that canary link is stronger than penguin link (strengthen the neural connection there)
==> your experience with these things should make a difference
- say that penguin is really a different kind of thing than canary
way to fix the “Violations of the
hierarchical order” problem
• Need to add a link from penguin to animal, ((but this violates the hierarchy.))
if you keep going with this you can have links going any direction anytime the reaction time is faster ==> get a breakdown of what it means to have a true hierarchy there
the relatedness effect
the slowing down when things are somehow similar
when you’re trying to make a judgment about some node (some category) but you’re slower because it’s similar in some salient way to another category
e.g. bats and birds (similar cause they both fly)
how is semantic memory generated?
not a single instance, but over many instances (Episodes) that you build up this semantic knowledge over time
Episodic memory is
detailed information for
specific autobiographical events (i.e. things that
happened to you).
how are memories organized in episodic memory?
The memories are temporally organized
(Tulving called this “mental time travel”).
you’re going through time and trying to retrieve one instance
in episodic memory there is an association between the memory and….
….its specific source.
e.g. high school graduation: the day is the source, the event is the source
Difference between episodic memory and semantic information
Unlike semantic information, the truth of a
memory can only be determined by the
individual (making it difficult to study).
Amnesia
is a loss of memory function
Amnesia is typically
characterized by four symptoms:
1) Anterograde
2) Retrograde
3) Confabulation
4) Key: Other intellectual functions remain intact
(tumors/infections)
Anterograde amnesia
New information can’t be learned (extends to both episodic & semantic).
cannot later remember events that occur after brain damage
ex: H.M.
Retrograde amnesia
Most typically old episodic memories cannot be retrieved and are patchy. (can be semantic too)
cannot remember events prior to brain damage
“TV amnesia”
Confabulation
for facts around time of injury you will make up stuff that sounds good (not intentionally lying)
you had things that weren’t quite encoded but you try to make sense of it
Amnesia in Korsakoff’s syndrome
usually develops after
prolonged alcoholism.
- Marked by severe anterograde amnesia.
- Usually retrograde amnesia as well, but it is temporally graded. (Patients have greater deficits for more recent events and faces.)
− Older memories are preserved better; this may be due to the effects of alcohol on encoding and storing those memories.
− Both episodic and semantic information are affected by Korskoff’s syndrome.
• Because both episodic and semantic information are affected perhaps they aren’t so different?
temporally graded
memory for events, info, is worse for more recent events and gets better for things that were further in the past
deficits greater for recent events
maybe older memories are preserved better?
alcohol affects encoding and learning so you’re not going to remember as much: not gunna encode or store things in LTM as you’re using more and more alcohol
Episodic/semantic distinction
Based on some neuropsychological evidence in retrograde
amnesia patients, there may be a double dissociation for
episodic and semantic memory.
• Patient K.C. had a damaged hippocampus (and surrounding
regions) and lost his episodic memory. Has general knowledge, but little detail.
• Italian woman with encephalitis lost general knowledge of people and places, but could remember specific life events.
- had episodic but lost categories (couldn’t tell you what things were)
*suggests that these two different functions are separable
what’s a double dissociation?
two different functions are independent and you show this independence by different types of brain damage
Perhaps episodic and semantic
memory work together?
• Episodic memory may build up and generalize over time in early childhood to give you a “base” for semantic memory.
− Semantic memory is strengthened by repetition (presenting more and more episodes over time).
• Once you have some semantic memories established, episodic
memories will be stronger when they are more novel or unusual or meaningful or emotional.
− e.g.You remember a really bad meal or strong emotional events. - if you had lots of similar episodes - the strength of those memories will go down and maybe they become the base for semantic information
In The Bourne Identity, Matt Damon played a character who
had severe episodic amnesia, but remembered all of his superspy
skills. He spends the movie(s) trying to figure out his past.
Which of the following is the best description of his condition?
Retrograde amnesia
declarative memory
knowing that something is true.
episodic and semantic:
* Knowing what you had for dinner last night (episodic). * Knowing whether or not it was nutritious (semantic).
Procedural Memory
knowing how to do something.
• How do you put toothpaste on your toothbrush? How do you shoot a free throw? * All skills and activities. * Hard to verbalize, but easy to do. (shoe tying)
Evidence from amnesia
We known that H.M. had severe anterograde amnesia for declarative
knowledge (both episodic and semantic), but what about perceptual
motor skills?
Brenda Milner (1965)
• gave H.M. a series of mirror tracing tests. You
trace an object, watching your movements in a mirror.
• As with normal controls, H.M. IMPROVED over time. However, he had no
memory of having done the task before.
• This demonstrates that declarative and procedural memory are two different systems
Explicit memory
conscious awareness
of an event or meaning.
- You know that you know.
- Can be recalled or recognized.
and once you’re explicitly aware of it you can declare it
Implicit memory
change in performance without conscious awareness of the cause (think latent learning).
- May be a skill (procedural), but not always.
- Classical conditioning: making unconscious associations between two different types of stimuli.
- Priming may activate a word meaning without awareness.
- Think of the recognition tasks from the CogLab assignment. Felt like you were guessing, but scored better than chance
Graf and colleagues (1985)
used REPETITION PRIMING to test explicit versus implicit memory.
• Presented a list of words twice and then tested subjects for recall (explicit) or word completion (implicit).
• At test, asked to recall a word that started “mar—-” or fill-in “mar___” with
the first letters that come to mind.
• Subjects were amnesic patients and two groups of control patients.
• Amnesic patients did worse on the recall test, but equally well on the
implicit memory task.
suggests that you can perform in such a way that you have a memory but not be consciously aware of it
Evidence from advertising
Perfect & Askew (1994)
building up a response to something without being explicitly aware and because it lasts over time it’s a type of memory
found that people are more likely to rate statements as being true if they have read them before.
• Called the propaganda effect, statements are more likely to be
believed even if they were stipulated as false on the first presentation.
- “The president is an alien from Mars and is here to steal our aluminum foil.”
- It is implicit memory because people will rate the statement as more likely true even if they don’t remember seeing or hearing it before.
propaganda effect
statements are more likely to be believed even if they were stipulated as false on the first presentation.
you repeat things and people accept them as true (manipulation)
mistake familiarity with truth
