Model of Memory Turning now to Long-Term Memory Sensory Signals Sensory Memory Short-Term Memory Long-Term Memory ATTENTION REHEARSAL RETRIEVAL

Long-Term Memory Characteristics (intuitive with some introspection): –Persists indefinitely (up to decades!) –Requires no active process of rehearsal (at least that we are conscious of)

Long-Term Memory Characteristics (intuitive with some introspection): –Persists indefinitely (up to decades!) –Requires no active process of rehearsal (at least that we are conscious of) –What are some examples of Long-Term Memories?

Some Distinctions in LTM Endel Tulving: There are two broad categories of information that are represented in LTM - Examples: –What did you eat for breakfast? –What is the capital of Canada –Where were you when… –Are maple trees deciduous? –Riding a bike !?

Some Distinctions in LTM Endel Tulving: There are two broad categories of information that are represented in LTM - Episodic Memory: memory of an event in your life autobiographical has a temporal context - something about time is encoded along with the memory

Some Distinctions in LTM Endel Tulving: There are two broad categories of information that are represented in LTM - Semantic Memory: memory of facts, knowledge of the world unconnected to an autobiographical event no temporal context

Some Distinctions in LTM A third category may be distinguished: –Example: riding a bike, playing an instrument

Some Distinctions in LTM Procedural Memory: memory for actions

Semantic Memory Capacity is huge (unlimited?)

Semantic Memory Structure of encoding is associative

Semantic Memory Structure of encoding is associative –Evidence: Semantic Priming in a Lexical- Decision Task Priming: prior exposure to some stimulus modifies subsequent processing of a target

Semantic Memory Structure of encoding is associative –Evidence: Semantic Priming in a Lexical- Decision Task Lexical Decision Task: Subject is shown a target word or pronounceable non-word (eg. gap or fap) and must respond “word” or “non-word”

Semantic Memory Structure of encoding is associative –Evidence: Semantic Priming in a Lexical- Decision Task manipulation: prime can be either related or unrelated to the target word

Semantic Memory Structure of encoding is associative –Evidence: Semantic Priming in a Lexical- Decision Task result: words are identified faster when preceded by a semantically related prime PrimeTargetResponse “space”“gap”fast “palace”“gap”slow

Semantic Memory Structure of encoding is associative –Evidence: Semantic Priming in a Lexical- Decision Task –Interpretation: the representation of information in semantic memory is associative: each fact or piece of knowledge is stored along with its relationship to other stored information related items can activate each other which facilitates recall

Semantic Memory Structure of encoding is associative –Example: Accessing a memory that is “on the tip of your tongue” recalling a movie you wanted to rent each recalled piece of knowledge “activates” related knowledge until the title is sufficiently activated

Semantic Memory Structure of encoding is associative –This idea is formalized in so-called “connectionist” networks bird canary chicken mockingbird To Kill A Mockingbird racism highschool Martin Luther King skiing Mr. Cassella physics

When You Don’t Remember Two reasons why you don’t remember semantic information:

When You Don’t Remember Two reasons why you don’t remember semantic information: Unavailable –It wasn’t successfully encoded - something when wrong while you were studying

When You Don’t Remember Two reasons why you don’t remember semantic information: Unavailable –It wasn’t successfully encoded - something when wrong while you were studying Inaccessible –memory is stored but cannot be retrieved, perhaps because appropriate connections aren’t being made

Recalling Memories Memory is affected by the nature of your engagement with the information Levels-of-Processing Theory

Recalling Memories Memory is affected by the nature of your engagement with the information Levels-of-Processing Theory –Consider this experiment: List CAT pie PILLOW TREE Method of Learning stating capitals or lower-case (surface processing) repeating words putting words into a sentence (deep processing) Recall is tested some time later.

Recalling Memories Memory is affected by the nature of your engagement with the information Levels-of-Processing Theory –Consider this experiment: Result: Best recall with “deep” processing Worst recall with “surface” processing List CAT pie PILLOW TREE

Recalling Memories Memory is affected by the nature of your engagement with the information Interpretation: –the successful use of memory depends on the number of connections that are made between related items and the degree to which these are initially activated

Recalling Memories context is critical! –location, physiological state, etc. affect ability to recall –e.g. lists of words are recalled better when recalled where they were first learned Similarities in context (especially smell) can trigger vivid recollections

Recalling Episodic Memory Recall is a generative process rather than simply calling up stored data

Recalling Episodic Memory Recall is a generative process rather than simply calling up stored data Evidenced by the fact that episodic memories can be distorted or completely false under certain circumstances

Recalling Episodic Memory Misinformation Effect - exposure to information subsequent to storage of memory can alter the contents of the memory

Recalling Episodic Memory Misinformation Effect Consider the following example: –Subjects were shown a video depicting a car accident

Recalling Episodic Memory Misinformation Effect Consider the following example: –Subjects were shown a video depicting a car accident –Then given the following question: “How fast were the vehicles going when they ______”

Recalling Episodic Memory Misinformation Effect Consider the following example: –Subjects were shown a video depicting a car accident –Then given the following question: “How fast were the vehicles going when they ______” –Different subjects were asked questions that differed in the “magnitude” of the final word

Recalling Episodic Memory Misinformation Effect Consider the following example: –Subjects were shown a video depicting a car accident –Then given the following question: “How fast were the vehicles going when they ______” –Different subjects were asked questions that differed in the “magnitude” of the final word –The possible words were: Contacted, Hit, Bumped, Collided, and Smashed

Recalling Episodic Memory Misinformation Effect Consider the following example: –Average estimated velocity depended on the nature of the question

Recalling Episodic Memory Misinformation Effect Interpretation: –Episodic memory can be distorted by subsequent information

Recalling Episodic Memory Misinformation Effect Interpretation: –Episodic memory can be distorted by subsequent information –Memory might be directly altered - the Changed-Trace Hypothesis –A second competing memory could be created by the question, which interferes with the initial memory - the Multiple-Trace Hypothesis

Recalling Episodic Memory Memory for episodes in life can be illusory

Recalling Episodic Memory Memory for episodes in life can be illusory Consider this example: –Subjects were given a list of words to remember via a video tape of a man and a woman speaking the words

Recalling Episodic Memory Memory for episodes in life can be illusory Consider this example: –Subjects were given a list of words to remember via a video tape of a man and a woman speaking the words –Then given a list of words, some but not all of which had been studied, and asked to indicate which speaker had said the word or indicate “not sure”

Recalling Episodic Memory Memory for episodes in life can be illusory Consider this example: –Subjects were given a list of words to remember via a video tape of a man and a woman speaking the words –Then given a list of words, some but not all of which had been studied, and asked to indicate which speaker had said the word or indicate “not sure” –87% of the unstudied words were attributed to one of the speakers !

Recalling Episodic Memory False Memories may arise when details of a crime are in question as in eye-witness testimony or repressed memories of abuse during childhood

Implicit and Explicit Memory: yet another distinction The successful recall of episodic memory entails a conscious awareness for the contents of the memory

Implicit and Explicit Memory: yet another distinction The successful recall of episodic memory entails a conscious awareness for the contents of the memory Explicit Memory is any memory that is both available and accessible by consciousness

Implicit and Explicit Memory: yet another distinction Are all memories explicit? Is all information stored in the brain subject to conscious scrutiny?

Implicit and Explicit Memory: yet another distinction Are all memories explicit? Is all information stored in the brain subject to conscious scrutiny? Implicit Memory refers to encoded memories that are not part of the “contents” of awareness

Implicit and Explicit Memory: yet another distinction How can we know whether memory is stored/recalled implicitly or explicitly?

Implicit Memory Consider the following distinction in recalling items from a list of words:

Implicit Memory Consider the following distinction in recalling items from a list of words: Free Recall - subjects can be asked to simply recall and report as many items as possible - these items are accessible as explicit memory

Implicit Memory Consider the following distinction in recalling items from a list of words: Implicit Recall - subjects can be asked to complete a word stem with any word that comes to mind after reading a list of words (no mention of testing memory!) __ack

Implicit Memory Consider the following distinction in recalling items from a list of words: Implicit Recall - subjects can be asked to complete a word stem with any word that comes to mind after reading a list of words (no mention of testing memory!) But how do you know that information is stored/recalled implicitly? Couldn’t it be explicit?

Implicit Memory Consider the following distinction in recalling items from a list of words: Twist - require subject to complete stem with a word that wasn’t on the list - if a word from the list is used preferentially, it was remembered implicitly

Implicit Memory Consider the implications regarding the nature of consciousness and the connection between neural activity and awareness

Next Time: –Repressed Memories by Beth Loftus –Tuesday - neuropsychology of LTM and discussion of The Lost Mariner by Sacks