Chapter 3 :Chapter 3 Episodic and Semantic Memory: Memory for Facts and Events Slides prepared by Mary Waterstreet, St. Ambrose University


3.1 Behavioral Processes :3.1 Behavioral Processes


3.1 Behavioral Processes :3 3.1 Behavioral Processes Episodic (Event) Memories and Semantic (Fact) Memories How Humans Acquire and Use Episodic and Semantic Memories When Memory Fails Learning and Memory in Everyday Life— Total Recall! The Truth about Extraordinary Memorizers Models of Semantic Memory


Episodic (Event) Memories and Semantic (Fact) Memories :4 Episodic (Event) Memories and Semantic (Fact) Memories Who sailed across the ocean blue in 1492? Christopher Columbus, of course. How many people remember where they were and what they were doing when they first heard about Columbus?


Episodic and Semantic Memories :5 Episodic and Semantic Memories Episodic memory—for a specific autobiographical event within a spatial and temporal context Most students do not remember where and when they first heard about Columbus. Semantic memory—for facts or general knowledge of the world But, most students know about Columbus.


Comparing and Contrasting Episodic and Semantic Memories :6 Comparing and Contrasting Episodic and Semantic Memories


Episodic and Semantic Memories :7 Episodic and Semantic Memories Declarative or explicit memory—general terms for episodic and/or semantic memory Memories are consciously accessible. Nondeclarative or implicit memory—other types of memory (includes motor skill memories; e.g., how to tie a bow) Memories are not always consciously accessible or easy to verbalize.


Can Nonhumans Have Episodic Memory? :8 Can Nonhumans Have Episodic Memory? Many nonhuman animals have knowledge of their world. e.g., locations of food, danger Little evidence that nonhuman animals demonstrate self-awareness or sense of time. Nonhuman episodic memory may be very different from human episodic memory.


Episodic Memory in Gorillas :9 Episodic Memory in Gorillas Gorilla learned to use cards with abstract drawings to represent certain fruits and humans (semantic learning). Used cards to identify fruit he had eaten the day before, as well as who gave it to him (episodic learning).


Episodic Memory in Scrub Jays :10 Episodic Memory in Scrub Jays Scrub jays bury worms and nuts in sand-filled ice-cube tray compartments. When allowed to recover food 4 hours later, chose worms (favorite food). After 124 hours, tended to choose the still edible nuts. Bird Talk Einstein the Parrott Shoplifting Seagull Dr. Nicola S. Clayton, University of Cambridge


How Humans Acquire and Use Episodic and Semantic Memories :11 How Humans Acquire and Use Episodic and Semantic Memories Memory is better for information that relates to prior knowledge (memory in context). In study, participants remembered twice as many story details if they saw a contextual sketch before hearing the story. *Application* Skim a textbook chapter for key points before you read its details.


Effects of Organization on Memory :12 Effects of Organization on Memory (a) Data from and (b) adapted from Bransford and Johnson, 1972.


Deeper Processing at Encoding Improves Recognition Later :13 Deeper Processing at Encoding Improves Recognition Later Depth of processing The more meaningfully you analyze information at encoding, the stronger the retrieval.


Deeper Processing at Encoding :14 Deeper Processing at Encoding In study, students studied some adjectives by generating related images. Deep processing Other adjectives were studied through backwards pronunciation. Shallow processing Students recognized more “image” words than “pronounce” words.


Deeper Processing at Encoding :15 Deeper Processing at Encoding Student fMRIs showed more brain activity during “image” encoding than during “pronounce” encoding. (a) Data from and (b) adapted from Davachi et al., 2003.


The Forgetting Curve and Consolidation :16 The Forgetting Curve and Consolidation Most forgetting occurs in the first few hours or days (Ebbinghaus). Squire tested adult memory for one season TV shows from 1 to 15 years prior. Remembered more than 75% of the previous year’s shows. Recollection dropped from 2 to 9 years. Remembered almost as many shows from 15 years ago as from 10 years ago.


Transfer-Appropriate Processing :17 Transfer-Appropriate Processing “Tip-of-the-tongue” phenomenon—when memory is temporarily inaccessible. Transfer-appropriate processing—retrieval more likely if cues at encoding and recall are similar. Context may be a factor (e.g., words to words or images to images). Depth of processing at encoding helps when retrieval requires deep processing (e.g., requires knowledge of semantic meaning).


Transfer-Appropriate Processing: Research :18 Transfer-Appropriate Processing: Research In study, divers studied some words underwater and others on the beach. Words learned underwater were best recalled underwater. Words learned on the beach were best recalled on the beach When learning and recall environments were radically different, recall dropped about 40%.


Transfer-Appropriate Processing: Research :19 Transfer-Appropriate Processing: Research But, in another study, college students took final exams in: The same room where the course was taught. A novel classroom. Students’ exam performance was not affected by testing in a new classroom.


*Demonstration* :20 *Demonstration* Write down as many names of the twelve presidents since WWII as you can remember. Don’t consult with your classmates; just use your own memory.


Who knows the Presidents? :21 Who knows the Presidents?


Who knows the Presidents? :22 Who knows the Presidents?


More Cues Mean Better Recall :23 More Cues Mean Better Recall Free Recall—generate response from memory. Cued Recall—a prompt given to facilitate response generation. Recognition—identify target from distracter items. *For those who did not recall all 12 president names, did recognition help?


When Memory Fails: Interference :24 When Memory Fails: Interference Interference—when two memories are similar, the strength of either or both may be reduced. Proactive interference—old information disrupts new learning. Retroactive interference—new information disrupts old learning.


Proactive Versus Retroactive Interference :25 Proactive Versus Retroactive Interference A simple mnemonic for remembering the difference between proactive and retroactive interference: PRoactive means PReviously-acquired information interferes with newly-acquired memories. REtroactive means REcently-acquired information is interfering with previously-acquired memories.


When Memory Fails: Source Amnesia :26 When Memory Fails: Source Amnesia Amnesia—memory loss Source amnesia—confusion over the source of a memory (fact or event) Includes cryptomnesia: Mistakenly thinking an idea is original. Can lead to unintentional plagiarism.


When Memory Fails: False Memory :27 When Memory Fails: False Memory False memory—memory for events that never occurred. In studies, Loftus and others created false memories by using plausible childhood events, family support, doctored photos. Prompt participants to imagine missing details. Participants confuse imagined details with reality.


False Memory for Words :28 False Memory for Words Participants saw and heard words, then wrote down the words they could recall in any order (free recall). Some recalled a word associated with all presented words but NOT seen or heard (i.e., a false memory). Identified during a recognition test. Did you recall the word ________?


False Memory for Studied Words :29 False Memory for Studied Words Data from Cabeza et al., 2001.


3.1 Interim Summary :30 3.1 Interim Summary Episodic memory = autobiographical events we “remember.” Semantic memory = general fact information we “know.” Both generally accessible to conscious recall, can be communicated flexibly.


3.1 Interim Summary :31 3.1 Interim Summary Key differences: Episodic memory—always acquired in single exposure; always includes spatial/temporal context. Semantic memory—strengthened by repeated exposure; need not include spatial/temporal information. Some believe only adult humans capable of true episodic memory. Have sense of self; can relive past experiences.


3.1 Interim Summary :32 3.1 Interim Summary Factors affecting successful episodic and semantic memory encoding/retrieval: Can information be related to preexisting knowledge? How is information processed (Deep or shallow)? Do encoding and recall conditions match? How many cues are available to prompt recall? Most simple forgetting occurs early after the event (e.g., Ribot gradient).


3.1 Interim Summary :33 3.1 Interim Summary Memories also lost or distorted through: Interference Source amnesia Cryptomnesia False memory Hierarchical semantic networks = model for information encoding. Links (relationships) between nodes (concepts or objects)


3.2 Brain Substrates :3.2 Brain Substrates


3.2 Brain Substrates :35 3.2 Brain Substrates The Cerebral Cortex and Semantic Memory The Medial Temporal Lobes and Memory Storage Hippocampal-Cortical Interaction in Memory Consolidation The Role of the Frontal Cortex in Memory Storage and Retrieval Unsolved Mysteries—Are There Different Brain Substrates for Episodic and Semantic Memory? Subcortical Structures Involved in Episodic and Semantic Memory


The Cerebral Cortex and Semantic Memory :36 The Cerebral Cortex and Semantic Memory Sensory cortices help process sensory information, including: Auditory cortex in superior temporal lobe. Visual cortex in the occipital lobe. Somatosensory cortex in parietal lobe. Association cortex links information within and across sense modalities.


Semantic Memory and the Cerebral Cortex :37 Semantic Memory and the Cerebral Cortex


Cerebral Damage and Semantic Memory :38 Cerebral Damage and Semantic Memory Agnosia—difficulty processing sensory information May result from cortical damage. Associative visual agnosia—patients cannot recognize or name objects (though they can may have ability to identify by feel, or draw). Agnosia can be specific to category (visual, auditory, tactile).


The Medial Temporal Lobes and Memory Storage :39 The Medial Temporal Lobes and Memory Storage Medial temporal lobes (MTL) includes: Hippocampus Amygdala entorhinal cortex perirhinal, cortex parahippocampal cortex Bilateral damage results in anterograde amnesia (cannot form new memories). H.M. case study


MTL in Humans :40 MTL in Humans


The Hippocampal Region and Memory in Nonhuman Animals :41 The Hippocampal Region and Memory in Nonhuman Animals Monkeys have similar MTL to humans. Rats and rabbits have same structures, different organization and structure sizes. Birds and reptiles have a single structure. Nonhuman animals with hippocampal region lesions experience anterograde amnesia.


Hippocampal Region in Animals :42 Hippocampal Region in Animals


The Hippocampal Region and Memory in Nonhuman Animals :43 The Hippocampal Region and Memory in Nonhuman Animals In studies: Healthy rats learned to find food at the end of all 8 arms of a radial maze with few errors. Rats with hippocampal lesions made many errors, losing track of which rewards they had already eaten. Lesioned scrub jays searched for their buried food caches randomly.


Hippocampal Function in the Healthy Brain :44 Hippocampal Function in the Healthy Brain In studies, fMRI shows more active MTL during encoding of words and images that participants successfully recalled. Successful word recall associated with left MTL and frontal lobe activation at encoding. Successful picture recall associated with bilateral MTL activation. Science Magazine/Courtesy of Anthony D. Wagner


Hippocampal-Cortical Interaction in Memory Consolidation :45 Hippocampal-Cortical Interaction in Memory Consolidation Those with anterograde amnesia may also experience retrograde amnesia (inability to retrieve memories closest to injury). E.P. case study: Experienced bilateral MTL damage from encephalitis. Severe amnesia for a decade of his adulthood, but strong childhood memories.


The Role of Frontal Cortex in Memory Storage and Retrieval :46 The Role of Frontal Cortex in Memory Storage and Retrieval Frontal cortices may be important in declarative memory development. Facilitates attention, judgment, cognitive control.


Unsolved Mysteries— Are There Different Brain Substrates for Episodic and Semantic Memory? :47 Unsolved Mysteries— Are There Different Brain Substrates for Episodic and Semantic Memory? Semantic learning depends on medial temporal areas (including entorhinal, perirhinal cortices). Hippocampus may be needed for extra ability to record autobiographical context of episodic memories.


Subcortical Structures Involved in Episodic and Semantic Memory :48 Subcortical Structures Involved in Episodic and Semantic Memory Diencephalon—structures include mammillary bodies and mediodorsal nucleus of thalamus Basal forebrain—structures at base of forebrain Fornix—arch-like fiber bundle, connects diencephalon and basal forebrain to hippocampus. Damage to diencephalon, basal forebrain or fornix causes anterograde amnesia.


Diencephalon and Basal Forebrain :49 Diencephalon and Basal Forebrain


The Diencephalon May Help Guide Consolidation :50 The Diencephalon May Help Guide Consolidation Korsakoff’s disease: Thiamine (vitamin B1) deficiency Sometimes accompanies chronic alcohol abuse. Patients act like they have MTL damage, but damage is to diencephalon and other structures. Diencephalon might mediate frontal cortex and hippocampus during memory formation; damage could cause anterograde and retrograde amnesia.


Basal Forebrain May Help Determine What the Hippocampus Stores :51 Basal Forebrain May Help Determine What the Hippocampus Stores Basal forebrain is a MTL regulator. Certain strokes can lead to basal forebrain damage, resulting in anterograde and retrograde amnesia. e.g. anterior communicating artery (ACoA) aneurysm With frontal cortex damage and Korsakoff’s disease, survivors may confabulate (confuse free associations with reality).


3.2 Interim Summary :52 3.2 Interim Summary Cerebral cortex stores semantic memories. Different kinds of cortical damage may present as disruptions in semantic abilities. Difficulties remembering the purpose or meaning of words, objects, faces. Many cortical areas are prey to false-memory effect. Activity is similar for false and familiar items Region in MTL may signal if memory is true/false.


3.2 Interim Summary :53 3.2 Interim Summary Hippocampal region is active during encoding of material that will be remembered later. Damage to hippocampal region typically presents as: Severe anterograde amnesia Failure to acquire new event memories. Retrograde amnesia Loss of memory for events that occurred before injury.


3.2 Interim Summary :54 3.2 Interim Summary Unclear if episodic memories can become fully independent of hippocampus, or if hippocampus always helps access to memories stored in cerebral cortex. Frontal cortex may help bind event memory with spatial/temporal context. Individuals with damage to frontal cortex are prone to source amnesia.


3.2 Interim Summary :55 3.2 Interim Summary Diencephalon and basal forebrain: Key roles in memory. Poorly understood. Damage to either area presents as anterograde amnesia similar to MTL damage memory loss.


3.3 Clinical Perspectives :3.3 Clinical Perspectives


3.3 Clinical Perspectives :57 3.3 Clinical Perspectives Transient Global Amnesia Functional Amnesia Infantile Amnesia


Transient Global Amnesia :58 Transient Global Amnesia Transient global amnesia—temporary memory disruption, often due to brief interruption of blood flow to the brain from: Head injury Low blood sugar Heart attack or stroke Tranquilizers Alcohol “blackouts”


Transient Global Amnesia :59 Transient Global Amnesia Starts suddenly, lasts for hours. Usually ends within a day or so. Severe anterograde amnesia for encoding new episodic memories. Patchy retrograde amnesia.


Functional Amnesia :60 Functional Amnesia Functional (or psychogenic) amnesia— results from psychological (rather than physical) cause. e.g., dissociative fugue Loss of personal identity due to severe psychological trauma. Can be faked for personal gain.


Infantile Amnesia:Three Potential Factors :61 Infantile Amnesia:Three Potential Factors Infantile amnesia—the universal forgetting of episodic memories prior to age 3 or 4. Potential Factors: Hippocampus and frontal cortex may need to develop to a certain level to encode and retrieve episodic memories.


3.3 Interim Summary :62 3.3 Interim Summary Transient global amnesia may be temporary. Possibly caused when MTL are unable to carry out normal encoding role. Functional amnesia may be temporary. May be caused by psychological trauma, rather than discernable brain injury.


3.3 Interim Summary :63 3.3 Interim Summary Infantile amnesia = general lack of episodic memories from first few years of life. Possibly due to: Immature brain structures. No cognitive sense of self. Absence of language skills.