7. Attention and Memory March 14, :18 PM

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1 7. Attention and Memory March 14, :18 PM Seizures: uncontrolled random firings of groups of neurons that can spread across the brain H.M. s seizures originated in the temporal lobes Removed parts of medial temporal lobes, including hippocampus, which did stop seizures, however, inhibited formation of long term memories Memory: the nervous system s capacity to acquire and retain usable skills and knowledge, allowing organisms to benefit from experience Memories often incomplete, biased, and distorted; can be altered subtly through tellings and retellings How does attention determine what is remembered? To get info into memory, one needs to pay attention Attention is the ability to direct something in ourselves; pay infers that there are costs associated with attending to some pieces of info over others Attention is limited tasks become difficult when there are too many at once Visual attention is selective and serial Anne Treisman made great advances in study of attention We automatically identify primitive features (colour, shape, orientation, movement), in our environments Separate systems analyze different visual features Parallel processing allows all systems to process info at same time; we can attend selectively to one feature by blocking the further processing of others Searching for one feat. is fast/automatic; searching for two is serial (need to look at stimuli one at a time), and effortful (takes longer and more attention) Conjunction task: when stimulus you are looking for is made of 2 simple feats. Auditory attention allows selective listening Hard to perform 2 tasks at same time if they rely on the same mechanisms (listening to 2 conversations) Talking on cell phone and driving more dangerous than talking to passenger (cell phone convo will not vary with driving conditions); hands free phones don t solve problem Cocktail party phenomenon (E.C. Cherry): you can focus on a single convo in the midst of a chaotic party, but a stimulus like hearing your name/juicy gossip can capture your attention Proximity and loudness influence what you attend to, but your selective attention can also determine what you hear

2 Shadowing: technique where one message delivered to one ear, and another to the other ear. Person asked to attend to one message and shadow it by repeating aloud. Participant usually notices unattended sound, but does not know about its context Selective attention can operate at multiple stages of processing Filter theory (Donald Broadbent): explains selective nature of attention Ppl have limited capacity for sensory info and screen incoming info, letting impt information in (like a gate) Some stimuli demand attention and shut off ability to attend to other things Stimuli that evoke emotion can capture attention b/c they provide impt info about threats in environment Object produces stronger attention when viewed as socially relevant than nonsocial (ex: faces provide impt social info like if someone is an appropriate mate/potential harm) Faces, especially when threatening, are prioritized over less meaningful stimuli Helps ppl focus on impt objects/threats in environment (adaptation) Decisions about what to attend to are made early in perceptual process, but unattended info is still processed to some extent (processed unconsciously) Change blindness: common failure to notice large changes b/c we cannot attend to everything in the vast array of visual info available; shows we can attend to limited info and discrepancies exist b/w what we actually see and what we think we see Our perceptions of the world are often inaccurate; we don t know how much info we miss around us What are the basic stages of memory? Memory is a form of information processing (similar to computer) Encoding phase: info is acquired and changed into neural code the brain can use (occurs at the time of learning) Storage phase: can last a fraction of a second or a lifetime; the retention of encoded representations over time that correspond to some change in the nervous system that registers the event Retrieval: recalling/remembering stored info to use it Modal memory model (Richard Atkinson and Richard Shiffrin): memory is a 3 part system involving sensory, short term/ working, and long term memory Sensory memory is brief Temporary memory system, lasting only a fraction of a second and closely tied to sensory systems So short we are often unaware it is operating Everything we remember is the result of neurons firing in the brain; we obtain all our info through our senses

3 Through rows of letters test, George Sperling concluded that the visual memory persisted for about one third of a second before fading to extinction Our sensory memories allow us to experience the world as a continuous stream rather than in discrete sensations Visual memory keeps info just long enough to connect one image with the next in a smooth way Working memory is active Info passed from sensory stores to short term memory Limited capacity memory system that holds info in awareness for a brief period (longer than sensory memory) Memory storage system that combines info from different sources and can work on the info we have in memory (also called immediate memory) Material in short term memory constantly replaced by new info Lasts 20 30s, then disappears unless info is actively rehearsed/repeated Memory span and chunking : Limit is generally 7 plus/minus 2 (memory span); recent research suggests this number is too high Varies among individuals Sometimes used in the measure of IQ Chunking: organizing info into meaningful units to make it easier to remember The working memory is updated to take in new info Done through retrieval, transformation, and substitution Sometimes only one of the processes is required to update the working memory Working memory s 4 parts: WM is an active processing unit dealing with multiple types of info (ex: sounds, images, ideas) Central executive: the control system. Encodes info from sensory systems and filters it to be stored in long term memory. Also retrieves info from long term memory. Relies on other 3 components which temporarily hold audio and visuospatial info/personally relevant info Phonological loop: encodes auditory info and is active whenever a person tries to remember words by reading, speaking, or repeating them ( inner voice ). Words are processed in the WM by how they sound rather than what they mean. Visuospatial sketchpad: processing visual info such as features and location. Episodic buffer: holds temporary info about oneself Long term memory is relatively permanent Nearly limitless Allows you to remember nursery rhymes from childhood, the meaning and spelling of words you rarely use, etc. Distinguishing LTM from WM: Distinguished through duration and capacity

4 Serial position effect: ability to recall items from a list is dependent on order of presentation; items presented in middle not remembered well (primacy effect when words presented first are remembered, recency effect when words presented last remembered) Primacy effects=ltm Recency effects=wm (questionable whether entirely responsible) LTM and WM highly interdependent, but can be separated What gets into LTM: Info enters permanent storage through a rehearsal Overlearning (repeated rehearsal of material), leads to improved memory Material studied through multiple sessions distributed practice is remembered better than massed practice/cramming Only info that helps us adapt to our environment is typically transformed into a LTM (of billions of thoughts everyday, we want to store only useful info) Evolutionary theory: memory allows us to use info to assist us in reproduction and survival (what is edible and what isn t, predators from prey, etc.) What are the different LTM systems? Researchers at UofT argue that memory is not just one entity, but is a process involving several interactions Systems share a common function (to retain info), but encode and store different types of info in different ways Explicit memory involves conscious effort Implicit memory: unconscious memories Explicit memory: process used to remember info we can say we know (what you had for dinner last night) Declarative memory: the cognitive info retrieved in explicit memory; knowledge that can be declared. Can involve words or concepts, visual images, or both. Explicit memory can be further divided: Episodic memory: a person s past experiences including info about the time and place the experience occurred Semantic memory: the knowledge of facts independent of personal experience Episodic and semantic are separate (evidence found in cases of brain injury where one is functional and one is not) Implicit memory occurs without deliberate effort Consist of memories w/o awareness therefore cannot be expressed in words Classical condition uses implicit memory Does not require conscious effort=automatic Used by advertisers; we are often unaware of how we think/feel Implicit attitude formation can affect our beliefs about ppl (ex: whether particular ppl are famous)

5 False fame effect: if all you remember about a name is that you ve heard it before, you will likely assume it belongs to a famous person Involved in repetition priming (the improvement in identifying/processing a stimulus that has been experienced previously) Procedural memory (motor memory): involves motor skills and behavioural habits (ex: stopping when you see a red light). Have an automatic unconscious aspect; consciously thinking about the behaviours interferes w/ the smooth production. Prospective memory is remembering to do something Future oriented; an individual remembers to do something in future time Remembering to do something takes up cognitive resources by reducing the # of items we can deal with or the # of things we can pay attention to Involves automatic and controlled processes Sometimes particular environments have retrieval cues (ex: seeing a particular person triggers the fact that you were supposed to tell them something) Jogging your memory helps avoid the effort of remembering How is information organized? Long term storage is based on meaning Memories are stored representations Retrieval often involves an explicit effort to access the contents of memory storage, but you often retrieve info w/o any effort, therefore retrieval is both implicit and explicit Levels of processing model (Craik and Lockhart, UofT): the more deeply an item is encoded, the more meaning it has and the more easily it is recalled Different types of rehearsal lead to different encoding: Elaborative rehearsal: encodes in more meaningful ways (thinking conceptually/making a connection); elaborating on basic info by connecting it with things in your LTM; remembered best Maintenance rehearsal: repeating the item over and over Schemas provide an organizational framework Structure in LTM that help us perceive, organize, process and use info Helps sort incoming info and guide our attention to an environment s relevant features Allow us to construct new memories by filling holes within existing memories Can lead to biased encoding b/c culture influences schemas Info is stored in association networks

6 An items distinctive features are linked so as to identify the item (Collins&Loftus) Each unit of info in the network is a node which is connected to other nodes Spreading activation models of memory: idea that activating one node increases the chance that nearby nodes will also be activated; the closer the nodes the stronger the association Stimuli in WM activate specific nodes in LTM increasing the ease of access to that memory Retrieval of some items leads to enhanced memory for related items For this process to occur, info must be organized logically Allows us to find needed info fast Retrieval cues provide access to long term storage Can be anything that helps a person sort through the vast data in LTM to access the right info Encoding specificity: Almost anything can be a retrieval cue Encoding specificity principle (Endel Tulving): anything that helps someone recall information from a memory Context dependent memory: based on things like physical location, odours, and background music (provide sense of familiarity) Internal cues (ex: mood), can facilitate recovery of info from LTM State dependent memory: enhancement of memory when internal states match during encoding and recall What brain processes are involved in memory? There has been intensive effort to identify memory s physical location Engram (Lashley): the physical site of memory storage Memory is distributed throughout the brain rather than confined to a specific region (equipotentiality) Memories stored in multiple regions and connected through memory circuits (Donald Hebb) Not all brain areas equally involved, though great deal of neural specialization occurs Different memory systems (ex: declarative and procedural), use different regions Lashley s failure to find critical brain regions for memory due to: Maze task he used involved multiple sensory systems so rats could compensate for loss of one with other senses Did not examine subcortical areas (impt for memory retention) Regions within temporal lobe impt for coding new memories (shown through H.M. case) Temporal lobes impt for declarative and implicit memory Cerebellum impt for how motor actions are learned and remembered

7 Amygdala for fear learning (type of classical conditioning) The medial temporal lobes are impt for consolidation of declarative memories Middle section of temporal lobe Consists of amygdala and hippocampus Damage to medial temporal lobe interrupts storage of new memories w/o impairing access to old ones Consolidation: process of immediate memories becoming lasting memories All learning leaves biological trail in the brain; results from changes in strength of neural connections that support memory and from construction of new synapses Medial lobe responsible for coordinating and strengthening connection among neurons, but actual storage most likely takes place in the particular brain region engaged during the perception, processing, and analysis of material being learned Reconsolidation: once memories activated they must be consolidated again to be stored back in the memory Suggests that when memories for past events are retrieved, they can be affected by new circumstances, and may differ from original memory Memories change when we use them and aren t accurate Opens possibility that bad memories can be erased by activating and reconsolidating them Spatial memory: Memory for the physical environment, including info on directions, locations, and cognitive maps Morris water maze test (mice swimming to platform) Hippocampal damage impairs special memory Hippocampus supported by place cells (neurons that fire when at a specific location) Frontal lobes involved in many aspects of memory Impt for episodic mem., WM, spatial mem., time sequences, and various aspects of encoding and retrieval Frontal lobes work together w/ other brain regions to coordinate the encoding, storage, and retrieval of memory Frontal lobes crucial for encoding (especially deep encoding tasks) Frontal activation good predictor for what will be remembered and forgotten Some researchers hypothesized frontal lobe plays role in the WM; patients w/ damage to frontal lobe often have difficulty following plans and goals (also purpose of WM) Frontal region active when info retrieved from LTM into WM or encoded from WM to LTM Neurochemistry underlies memory

8 Memories involve alterations in connections across synapses; as memories are consolidated, neurons link to distributed networks which become linked Various neurotransmitters can weaken or enhance memory; known as memory modulators Neurochemistry indicates the meaningfulness of stimuli: Impt events lead to neurochemical changes that produce emotional reactions which make them especially likely to be stored in memory Minimally arousing tasks are stored minimally Adrenaline shows memory enhancement; not secreted within brain, but into bloodstream, therefore does not directly influence memory Researchers initially believed it affected memory b/c it causes release in glucose, which enters brain and influences memory storage More recent studies suggest epinephrine enhances memory b/c of effect on norepinephrine activity in the amygdala Other drugs enhance memory too The amygdala and neurochemistry of emotion: Arousing event= greater activity of norepinephrine receptors= stronger memory of event Amygdala has norepinephrine receptors and is involved in the memory of fearful events Emotional memory activates right, not left amygdala in men (opposite in women) Women have better memory than men for emotional events Effects of amygdala activity on memory are long lasting Post traumatic stress disorder: mental health disorder that involves frequent recurring unwanted thoughts related to the trauma; may experience memory and attention problems later (inability to forget). Hyper alert to stimuli associated with traumatic event, leading to activation of amygdala When Do People Forget? Forgetting is the inability to retrieve memory from long term storage Occurs rapidly over the first few hours and days but then levels off Seven sins of memory transience, absentmindedness, blocking, misattribution, suggestibility, bias, persistence

9 Transience Is Caused by Interference Pattern of forgetting over time Proactive interference: prior information inhibits our ability to remember new information Retroactive interference: new information inhibits our ability to remember old information Blocking Is Temporary Occurs when a person has a temporary inability to remember something that is known

10 Similar words keep recurring as we try to remember the target word Tip of the tongue phenomenon: people experience great frustration as they try to recall specific words that are somewhat obscure Absentmindedness Results from Shallow Encoding Inattentive or shallow encoding of events caused mainly by failing to pay sufficient attention to details Change blindness: inability to detect changes to an object or scene Amnesia Is a Deficit in Long Term Memory Results from disease, brain injury, or psychological trauma Damage to medial temporal lobes, other subcortical areas (e.g. around the thalamus) Retrograde amnesia: loss of past memories for events, facts, people, or personal information Anterograde amnesia: loss of the ability to form new memories Korsakoff s syndrome: severe form of memory disturbance linked to chronic alcoholism Vitamin deficiency that results in thalamic damage How are memories distorted? Human memory is biased, flawed, and distorted Flashbulb memories can be wrong Vivid memories for the circumstances in which one first learned of a surprising, consequential, or emotionally arousing event Do you remember where you were when you heard Better memory for the flashbulb experience occurs among those who found the news surprising and felt the event was impt Ex: ppl living in NYC have the most accurate memories of 911 Stress and memory revisited: Flashbulb memories are not completely accurate, but ppl more confident about flashbulb memories than ordinary events Any event that produces a strong enough emotional response is likely to produce a vivid, not completely accurate memory Distinctive event might simply be recalled more easily than a trivial event (Restorff effect)

11 Possible that greater media attention to major events leads to greater exposure to details=greater memory People make source misattributions The misremembering of the time, place, person or circumstances involved w/ a memory (Schacter) One of seven sins Ex: False fame effect Sleeper effect: arguments that initially are not very persuasive b/c they come from questionable sources become more persuasive w/ time; over time you might remember the argument but fail to remember the source Cryptomnesia: When a person thinks they came up with a new idea, but really have retrieved an old idea from memory and failed to attribute the idea to its proper source People are bad eyewitnesses Cross ethnic identification: Ppl particularly bad at accurately identifying individuals of other ethnicities/races Ppl tend to have less frequent contact w/ members of other races Ppl encode race and ethnicity based on rules and categories and don t notice much about the individual Suggestibility and misinformation: Ppl can develop biased memories when provided misleading info Car example: effect of word choice, smashed or bumped By retelling story over and over, witness may develop stronger memories for inaccurate details Eyewitness confidence: Eyewitness who are wrong are just as confident, if not more confident, than those who are right Eyewitnesses to real crimes tend to be focused on things like weapons, not minor details Strong confidence for minor details may indicate the memory is false People have false memories Source amnesia: when a person has a memory for an event but cant remember where they encountered the info Most ppl cant remember specific memories from before age 3 Absence of early memories (childhood amnesia), may be b/c of early lack of linguistic capacity as well as immature frontal lobes When a person imagines an event happening, they form a mental image, which may be confused with a real memory (person struggles to monitor the source of the image)

12 Children especially susceptible Confabulation: Unintended false recollection of episodic memory; honest lying Ppl recall mistaken facts and try to make sense of it when questioned (H.W.) Capgras syndrome: patients believe their family members have been replaced by imposters; even when confronted with contradictory evidence they persist in inventing facts that support their delusions (often result of damage to frontal lobes and limbic regions) Most likely cause is that region involved in emotion is separated from visual input; visual image remains the same, but emotion is different Repressed memories are controversial Long repressed traumatic memories can resurface during therapy (memories of childhood sexual abuse more common) Little evidence indicates that recovered memories are genuine/believable False memories for traumatic events have been implanted by well meaning but misguided therapists (Schacter) Children can be induced to remember events that didn t occur (ex: many adults falsely accuse their parents of abusing them as a result of therapy) People reconstruct events to be consistent Memory bias: the changing of memories over time in ways consistent with current beliefs/attitudes Ppl tend to recall their past attitudes as being consistent with their current beliefs, often revisiting memories when they change their beliefs Ppl tend to remember events as casting them in prominent roles/favourable light Exaggerate roles and remember success more than failure Neuroscience may make it possible to distinguish between true and false memories If the memory is true, same brain regions should be activated when recalling the memory as when the event occurred/initial encoding If false, unrelated brain areas activated One problem is that false memories tend to be similar to true memories in many ways (may correctly recall event in gym class, but incorrectly recall teacher) How can we improve learning and memory? Mnemonics are useful strategies for learning Strategies for improving memory Practice: The more times an action is repeated, the easier it is to perform

13 Memories are strengthened with retrieval Repeated testing in school is a good way to strengthen memory Elaborate the material: Deeper processing=increased likelihood of remembering Critical thinking skills impt; organizing info in a way that is meaningful to you is helpful Overlearn: Recognition is easier than recall Rehearse material even if you think you already know it Distributing study time is more effective Adequate sleep: May help with consolidation/joining of memories Chronic sleep deprivation interferes w/ learning Verbal mnemonics: Advertisers often create slogans that rely on mnemonics Ex: cells that fire together wire together Use visual imagery: Creating mental image of material helps you remember Working memory has very verbal component (phonological loop), and visuospatial component sometimes called sketchpad Method of loci: visualizing yourself placing objects in familiar locations so when you have to retrieve the material you just imagine going to that location Pegs: a list of key words Technique involves learning pegs, then hanging new words on those pegs by visualizing the new words together with pegs