cognitive processes psy 334nalvarado/psy334 ppts/pdfs/chap6.pdf · 2015-07-21 · memory – 1885....
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Cognitive ProcessesPSY 334
Chapter 6 – Human Memory: Encoding and Storage
Ebbinghaus
First rigorous investigation of human memory – 1885.Taught himself nonsense syllables
DAX, BUP, LOCSavings – the amount of time needed to relearn a list after it has already been learned and forgotten.Forgetting function – most forgetting takes place right away.
Memory Models
Atkinson & Shiffrin – proposed a three-stage model including:
Sensory store – if attended goes to STMShort-term memory (STM) – if rehearsed goes to LTMLong-term memory (LTM)
No longer the current view of memory.Still presented in some books.
The Three-Stage Model
Environment Sensory store Short-term (working) memory Long-term memory
Responses
Executive control processes
Sensation/perception Attention
encoding
retrieval
Retention Times
Environment Sensory store Short-term (working) memory Long-term memory
encoding
retrieval
1-3 seconds 15-25 seconds 1 sec to a lifetime
Sensory Memory
Holds info when it first comes in.Allows a person to extract meaning from an image or series of sounds.Sperling’s partial report procedure:
A display of three rows of letters is presented.After it is taken away, a tone signals which row to report.Subjects were able to report most letters.
Sperling’s Partial Report
A medium tone signals the subject to report the letters in this row
Sperling’s Results
Delay
Kinds of Sensory Stores
Iconic memory – visualBright postexposure field wipes out memory after 1 sec, dark after 5 sec.
Echoic memory – auditoryLasts up to 10 sec (measured by ERP)
Located in the sensory cortexes.
Short Term Memory
The original idea is that when info in sensory memory is paid attention to, it moves into short term memory.With rehearsal, it then moves into long term memory.STM has limited capacity, called memory span.
Miller’s magic number (7 ± 2)New info pushes out older info (Shepard)
Shepard’s Results
Number of intervening items
Probability of recalling the target item
Criticisms of STM
Rate of forgetting seemed to be quicker than Ebbinghaus’s data, but is not really.Amount of rehearsal appeared to be related to transfer to long-term memory.
Later it was found that the kind of rehearsal matters, not the amount.Passive rehearsal does little to achieve long-term memory.
Information may go directly to LTM.
Depth of Processing
Craik & Lockhart – proposed that it is not how long material is rehearsed but the depth of processing that matters.Levels of processing demo.
Working Memory
Baddeley – in working memory speed of rehearsal determines memory span. Articulatory loop – stores whatever can be processed in a given amount of time.
Word length effect: 4.5 one-syllable words remembered compared to 2.6 long ones.1.5 to 2 seconds material can be kept.Visuopatial sketchpad – rehearses images.Central executive – controls other systems.
Word-Lenth Determines Forgetting
Delayed Matching Task
Delayed Matching to Sample – monkey must recall where food was placed.
Monkeys with lesion to frontal cortex cannot remember food location.Human infants can’t do it until 1 year old.
Regions of frontal cortex fire only during the delay – keeping location in mind.
Different prefrontal regions are used to remember different kinds of information.
Delayed Matching to Sample
Importance of Frontal Cortex
In primates, working memory is localized to the frontal cortex.Delayed matching to sample task:
Monkeys are shown food that is then hidden.Later they are given a chance to locate it.
Monkeys with frontal lobe lesions cannot do this task.
Activation
Activation – how available information is to memory:
Probability of access – how likely you are to remember something.Rate of access – how fast something can be remembered.
From moment to moment, items differ in their degree of activation in memory.
Anderson’s ACT Model
ACT – Adaptive Control of ThoughtMoses Effect -- subjects shown the words Bible, animal and flood should recall Noah but recall Moses instead.
When given the word flood they think of Mississippi or Johnstown but not Noah.
Why? Recall is based on both baseline and activation from associated concepts.
Moses and Jesus have higher baselines.
The ACT Model
Factors Affecting Activation
How recently we have used the memory:
Loftus – manipulated amount of delay1.53 sec first time, then 1.21, 1.28, and 1.33 with 3 items intervening.
How much we have practiced the memory – how frequently it is used.
Anderson’s study (sailor is in the park)
Spreading Activation
Activation spreads along the paths of a propositional network.
Related items are faster to recall.Associative priming – involuntary spread of activation to associated items in memory.
Kaplan’s dissertation – cues to solving riddles hidden in the environment led to faster solutions.
Associative Priming
Meyer & Schvaneveldt – spreading activation affects how quickly words are read.
Subjects judged whether pairs of related & unrelated items were words.Judgments about related words were faster.
Meyer and Schvaneveldt
Practice and Strength
The amount of spreading activation depends on the strength of a memory.Memory strength increases with practice.Greater memory strength increases the likelihood of recall.
Power Function
Each time we use a memory trace, it gradually becomes a little stronger.Power law of learning:
T = 1.40 P-0.24
T is recognition time, P is days of practice.Linear when plotted on log-log scale.
Learning Curves
Practicing Addition Problems
Long Term Potentiation (LTP)
Neural changes may occur with practice:
Long-term potentiation (LTP) in hippocampus.Repeated electrical stimulation of neurons leads to increased sensitivity.
LTP changes are a power function.
Neural Changes Mirror Behavioral Changes
Neural Correlates of Encoding
Better memory occurs for items with stronger brain processing at the time of study:
Words evoking higher ERP signals are better remembered later.Greater frontal activation with deeper processing of verbal information.Greater activation of hippocampus with better long-term memory.
Activation in Prefrontal Cortex
Words activate left prefrontal cortex
Pictures activate right prefrontal cortex
Hemodynamic = blow flow during brain activity
Factors Influencing Memory
Study alone does not improve memory –what matters is how studying is done.
Shallow study results in little improvement.Semantic associates (tulip-flower) better remembered than rhymes (tower-flower), 81% vs 70%.
Better retention occurs for more meaningful elaboration.
Elaborative Processing
Elaboration – embellishing an item with additional information.Anderson & Bower – subjects added details to simple sentences:
57% recall without elaboration72% recall with made-up details added
Self-generated elaborations are better than experimenter-generated ones.
Self-Generated Elaborations
Stein & Bransford – subjects were given 10 sentences. Four conditions:
Just the sentences alone – 4.2 adjectivesSubject generates an elaboration – 5.8Experimenter-generated imprecise elaboration – 2.2Experimenter-generated precise elaboration – 7.8
Precision of detail (constraint) matters, not who generates the elaboration.
Advance Organizers
PQ4R method – use questions to guide reading.
64% correct, compared to 57% (controls)76% of relevant questions correct, 52% of non-relevant.
These study techniques work because they encourage elaboration.
Question making and question answering both improve memory for text (reviewing is better than seeing the questions first).
Meaningful Elaboration
Elaboration need not be meaningful –other sorts of elaboration also work.Kolers compared memory for right-side-up sentences with upside-down.
Extra processing needed to read upside down may enhance memory.
Slamecka & Graf – compared generation of synonyms and rhymes. Both improved memory, but synonyms did more.
Slamecka & Graf’s Results
Mnemonics
Method of Loci – place items in a location, then take a mental walk.Peg-word System – use peg words as a structure and associate a list of items with them using visualization.
Create acronyms for lists of items.Convert nonsense syllables (DAX, GIB) into meaningful items by associating them with real words (e.g., DAD).
“This Old Man” Song
http://www.youtube.com/watch?v=3cYf9vkW_xU
http://www.totlol.com/watch/5d-6Q5V79CM/This-Old-Man/0/
Pegword System1 – bun2 – shoe3 – tree4 – door5 – hive6 – sticks7 – heaven8 – gate9 – wine10 -- hen
Incidental Learning
It does not matter whether people intend to learn something or not.
What matters is how material is processed.Orienting tasks:
Count whether work has e or g.Rate the pleasantness of words.Half of subjects told they would be asked to remember words later, half not told.
No advantage to knowing ahead of time.
Awareness of Learning
Flashbulb Memories
Self-reference effect -- people have better memory for events that are important to them and close friends.Flashbulb memories – recall of traumatic events long after the fact.
Seem vivid but can be very inaccurate.Thatcher’s resignation:
60% memory for UK subjects, 20% non-UK
Self-Reference Effect
Two explanations:People have special mechanisms for encoding info relevant to themselves.Info relevant to the self is rehearsed more often.
High arousal may enhance memory.Memory is better for words related to the self – perhaps due to better elaboration.
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