Transcript Chapter 7
Memory Memory Three Stages of Memory: An Information-Processing View Information processing theories ◦ Brain and computer operations are similar Information-processing model ◦ Operations: input, storage, and retrieval ◦ Variety of control mechanisms at each point Information-Processing Theory Sensory information STORAGE economics literature INPUT RETRIEVAL Information is taken into brain Information is used as basis of behaviors and interactions culture science religion history math Information gets processed, analyzed, and stored until use Memory Memory Information-processing model ◦ Information enters through sensory receptors ◦ Attention selects information to be entered ◦ Information encoded for next memory stage ◦ Some memory is saved, other information is lost or discarded Stage theory of memory ◦ Assumes humans have 3-stage memory lasts less Discarded than a second, interprets stimulus Stimuli (input) Sensory Register Discarded Working Memory (Short-term Memory) Long-Term Memory (increasing or decreasing availability) Response (output or reaction behavior) Control Processes (selective attention, emotional regulation, strategic thinking) Memory Stages of Memory Sensory register ◦ Holds image or experience until processing ◦ Can last up to 4 seconds; usually lasts less Short-term memory (STM) ◦ Usually attention transfers information from sensory register to STM ◦ Usually information lasts less than one minute unless control processes like rehearsal and chunking are used Demonstration Attend to the words in the green box as they flash on the screen. When the last word disappears, write down as many words as you can recall. TABLE SNOW FOOT DOG SON END HAT BUS BREAD DOOR CAT Memory Stages of Memory ◦ Rehearsal – mental repetition of information Humans have preference for transforming information into acoustic codes or sounds ◦ Chunking – grouping information into bits Capacity limited to 7 items plus or minus 2 Rare to hold between 5 and 9 items in STM STM functions ◦ Temporary storage of information ◦ Serves as working memory: space used for retrieved memories from long-term memory Accuracy of recall for a single group of three consonants declines rapidly when subjects are prevented from rehearsing by being asked to count backwards Percent of accuracy of recall 100 80 60 40 20 0 0 3 6 9 12 Interval before recall in seconds 15 18 Memory Stages of Memory Differences between LTM and STM Volume: vast amount ◦ Indexed and retrieved selectively by cues • Type of information – In terms of meaning or semantic codes • Durability Processing location – Appears to be ◦ STM – frontal lobes permanent, of cortex forgetting occurs ◦ LTM – hippocampus then transferred to other brain areas Memory Types of Long-Term Memory Procedural ◦ Memory for skills and procedures (how to) Episodic ◦ Information about time and places (when, where) Semantic ◦ Memory for meaning (importance) Memory Long-Term Memory Long-term memory ◦ Storehouse for almost unlimited information over long periods of time ◦ Easy to store procedural and semantic memories, but stores episodic information less well ◦ Semantic and episodic memories grouped together as declarative memory Types of Long Term Memory Declarative memory Semantic memory “I know what a guitar is.” Procedural memory Episodic memory “I remember buying my first guitar.” “I remember how to play a guitar.” Memory Organization in Long-Term Memory Organization eases retrieval process ◦ Grouped into categories ◦ Associative network: memories linked together through experience ◦ Spreading activation model: representations of concepts and their characteristics are activated (ie: canary and bird) Closeness of association affects retrieval time – distant associations take longer Example of Associative Links Tiger Cat Animal Skin Dog Breathes Pat Sparrow Bird Canary Green Robin Ostrich Red Orange Feathers Yellow Sings Memory Retrieval of Long-Term Memories Frustration of unable to retrieve information Three ways to test retrieval ◦ Recall method: recall cues or hints used for ◦ Recognition method: select correct from alternative information (ie: multiple choice) ◦ Relearning method: relearn previous learned information Memory Serial Learning Order of memorizing is as important as items on the list Serial position effect – better recall of items at beginning and end of lists ◦ Affected by timing or delay of recall ◦ Involves simultaneous use of STM and LTM Tip-of-the-tongue phenomenon ◦ Most recall occurs within a few minutes Effects of Recall Timing on Short-Term Memory 80 Tested immediately Test delayed 20 seconds Proportion correct 70 60 50 40 30 20 0 1 2 3 4 5 6 7 8 9 10 Position in original list 11 12 13 14 15 16 Memory Levels of Processing: An Alternative to the Stage Model Two levels of memory processing Distinction between STM and LTM ◦ Matter of degree, not separate stages ◦ Differing levels of processing during encoding process Memory Levels of Processing: An Alternative to the Stage Model Processing continuum ◦ Shallow level – processed briefly ◦ Deeper level – processed much deeper involves greater elaboration (creating more associations between new and existing memories) An excellent way to improve memory Memory Forgetting and Why It Occurs Decay theory ◦ Unused memories fade gradually over time ◦ Causes of forgetting fading memory traces over time Interference with retrieval Memory Forgetting and Why It Occurs Interference theory ◦ Other memories interfere with retrieval ◦ Interference mostly from similar memories Types of interference ◦ Proactive – interference from prior learning ◦ Reactive – interference from later learning Memory Forgetting and Why It Occurs Interfering with STM ◦ Overloading STM capacity or weakening/ blocking an item out of storage Interference with LTM ◦ Interference plays lesser role in disrupting semantic memories than in episodic memories Memory Reconstruction (Schema) Theory Schemas – associative networks of beliefs, knowledge, and expectations ◦ During retrieval process, LTM information recalled in distorted and incorrect manner that is consistent with our schemas May occur because brain stores meaning better than episodic details May result in false memory – recalling something that never happened Memory Motivated Forgetting Freud: some threatening information is repressed – pushed into unconsciousness Emotional arousal improves memory in some ways or has little effect on memory ◦ Mild levels of positive and negative arousal appear to enhance memory ◦ Emotion-laden violence on TV programs decreases recall of program advertisements Memory Human Diversity: Cultural Circumstances and Memory Skills Kearins – environmental demands and culture may influence type of memory used ◦ Aboriginals have better visual memory skills Memory Biological Basis of Memory Synaptic theories of memory ◦ Physical change must occur in nervous system ◦ Engram: something remaining after learning ◦ Synaptic facilitation (Hebb) is biological basis of learning and memory Individual experiences produce unique patterns of neural activity causing structural changes in synapses Memory Biological Basis of Memory Synaptic theories of memory ◦ Classical conditioning of snails (Kandel) Amount of neurotransmitter in synapse increased – synapse holds memory Drugs that interfere with protein synthesis block memory formation Consolidation – fragile memories grow more permanent over a few minutes Memory Stages of Memory and the Brain STM and LTM differences in brain ◦ In role of synaptic changes: synapse changes involved in LTM but not STM ◦ In brain structures involved Three stages of memory involve various structures of brain as information is stored and retrieved ◦ Allows memory recall with visual images or auditory sensations Memory Amnesia: Disorders of Memory Retrograde amnesia ◦ No memory of what happened immediately before an accident or highly stressful event Little or no disruption in STM New long-term memories can be formed Usually memory loss does not last lifetime Stress of event disrupts consolidation and retroactive interference blocks retrieval Memory Amnesia: Disorders of Memory Anterograde amnesia ◦ Inability to store and retrieve new information ◦ Case of H.M. – epilepsy and neurosurgery Does not affect procedural memory abilities but disrupts episodic memory formation Hippocampus involved in episodic memory ◦ Damage prevents formation of new long-term declarative memories Memory Amnesia: Disorders of Memory Korsakoff’s syndrome ◦ Brain disorder from prolonged loss of vitamin thiamine as in diet of chronic alcoholics ◦ Extreme degree of memory loss ◦ Often engage in confabulation – cannot remember ending to a statement so make it up; an exaggerated version of normal reconstruction distortion Memory Inaccurate Recall Due to Biased Questioning Research on eyewitness information ◦ Can be potent source of distortion Interviewer questions can contain cues that influence retrieval Reconstruction theory of forgetting – people remember something that did not occur because it seemed consistent with the event Perceived expertise of interviewer may bias informational response Memory Inaccurate Eyewitness Recall Eyewitness testimony frequently inaccurate ◦ Children, adolescents are particularly suggestible when interviewed by adults Sometimes describe what never happened Neutral questions get best results Eyewitnesses who look but do not see ◦ Some things processed in shallow ways due to inattentiveness or lack of importance attached Memory Stereotypes and Eyewitness Testimony Allport: memories distorted by prejudices ◦ Research in US – common African American names more stereotyped with criminality when memories fit personal schemas of prejudice Inaccurate recall due to characteristics of the eyewitness ◦ Being tired, upset, intoxicated may effect recall ◦ Drunk eyewitness: visual recall may be accurate in some circumstances Memory Recall of Repressed Memories of Sexual and Physical Abuse Most compelling testimony is from victims ◦ Many cases of repressed memories when adult was abused as child now in media Dilemma - hard to know what is accurate Many traumatic childhood memories discovered in psychotherapy may be false memories Memory Hypnosis and Eyewitness Testimony Hypnotizing witnesses to crimes is controversial ◦ Hypnotic age regression: hypnotized person goes back in time to earlier age – relives event and recalls forgotten experiences May be heightened imagination more than accurate relived memories ◦ Hypnotized witnesses to recent crimes may have more accurate recall Memory Improving the Accuracy of Eyewitnesses’ Testimony Thousands of experiments in research have raised concerns but little has been done ◦ DNA saved innocent persons on death row convicted on eyewitness testimony ◦ U.S. Dept. of Justice made recommendations in 1999 about use of eyewitness testimony Memory Eyewitness Testimony Recommendations ◦ Establish good rapport ◦ Ask open-ended questions ◦ Use fillers in lineup fitting witness description ◦ Place only one suspect in identification lineup ◦ Unbiased instructions to eyewitnesses before viewing photos and lineups ◦ Avoid giving feedback to eyewitnesses after identification of photo or person in lineup Memory The End