Memory II Reconstructive Memory Forgetting
Observe this crime scene
What does a penny look like?
Memory Biases Memory is better for meaningful significant features than for details of language or perception gist is remembered better than detail
Label distorts memory of objects Carmichael, Hogan, & Walter (1932)
Reconstructive nature of memory Memory is often side-effect of comprehension details can be filled in or reconstructed Constructive approach to memory: Memory = actual events + knowledge, experiences, expectations
Effect of Expectation on Memory A simple demonstration experiment I am going to show you a picture of a graduate student s office. Just take a look at it for a while
Now write down all the things you can remember Potential responses: Chairs Desk Table Boxes Bottle of wine Picnic basket Books Skull Brewer & Treyens (1981): 30% of subjects (falsely) recalled that books were present
Misinformation Effect Memory for event can be influenced by information given after the event Elizabeth Loftus
Misinformation Effect Subjects view a movie of a car accident Different expressions used to describe car contact Subjects estimate speed of a car at time of contact
Misinformation Effect
Explaining Misinformation Effect Three hypotheses Overwriting misleading information alters the memory trace Source confusion Sometimes we misremember the source of a memory Perhaps the memory of the question is confused with the memory of the visual scene Misinformation acceptance Ss. believe the information in the postevent is true
Overwriting Hypothesis seems unlikely McCloskey and Zaragoza (1985) See event: yield sign Receive misinformation, as the car passed the... misleading:...stop sign? nonmisleading:...yield sign? Test: yield sign OR stop sign 35% drop in accuracy for misleading information yield sign OR no U-turn no difference in accuracy for misleading information (both groups much higher than chance)
Relevance to Criminal Justice System most obvious case crime study picture of suspect (mugshot) misinformation Lineup test Eyewitness may recognize suspect from mugshot, not from crime scene. Conclusions: Do not let potential witnesses see suspects. Interrogate without asking leading questions
Traditional Lineup 1 2 3 4 5 6 7 8
Sequential Lineup 1 2 3 4 5 6 7 8
Recovery of Lost Memories? Several lawsuits have relied on eyewitness testimony of repressed memories. These memories were recovered by family member or therapist Claim: repression follows stress, but repressed material can be returned to consciousness with the removal of stress (e.g., Zeller, 1950, 1951; Merrill, 1954) Problem: Are these repressed memories or false memories (based on misinformation)?
Recovered memory vs. False Memory How do we know whether repressed memories are accurate? Hard to falsify In some cases, traumatic information is misremembered or simply made up Loftus has been involved in many cases Points out problems of hypnosis suggestive questioning dream interpretations
Can false memories be implanted? Loftus and Pickrell (1995)
Imagination Inflation
False Memory in the Lab Deese, Roediger, McDermott paradigm Study the following words Recall test... Recognition memory test SLUMBER BLANKET DROWSY SNOOZE DREAM AWAKE SNORE PEACE TIRED YAWN DOZE REST BED NAP Use ratings 1) sure new 2) probably new 3) probably old 4) sure old TEST: COFFEE SNORE SLEEP REST
Results Critical lure ( sleep ) are words not presented but similar to studied words. These words are often falsely recalled (sleep: 61% of Ss.) Recognition memory results proportion of items classified with confidence levels: confidence rating 4 3 2 1 studied items.75.11.09.05 not studied unrelated.00.02.18.80 critical lure.58.26.08.08 (e.g. REST ) (e.g. COFFEE ) (e.g. SLEEP )
Accuracy and Confidence Eyewitness testimony requires accuracy and confidence eyewitness testimony is likely to be believed by jurors, especially when it is offered with a high level of confidence (Loftus, 1979) Should we rely on the confidence level given by a witness ( I am sure I saw this )? False memory experiment shows sometimes confidence is high while accuracy is low
Forgetting
Forgetting Functions Ebbinghaus (1885/1913): Forgetting over time as indexed by reduced savings. Most forgetting functions show: Negative acceleration Rate of change gets smaller and smaller with delay Power law of forgetting
Why do we forget? Some possibilities: Memory has disappeared decay theory Memory is still there but we can t retrieve it interference theory e.g. blocking inhibitory mechanisms e.g. retrieval induced forgetting supression
Example You call a friend, but realize you need an older phone number that you have not used for a while. With effort, you recall the correct old phone number Explanation 1: the old number is blocked by the new association FRIEND NEW PHONE NUMBER OLD PHONE NUMBER
Example You call a friend, but realize you need an older phone number that you have not used for a while. With effort, you recall the correct old phone number FRIEND Explanation 2: the old memory has been suppressed Retrieval induced forgetting NEW PHONE NUMBER OLD PHONE NUMBER
Evidence for Retrieval Induced Forgetting Blocking would predict that using a new cue would remove blocking effect. Suppression would predict the memory cannot be accessed with a new cue either some evidence for suppression FRIEND OTHER MEMORY CUES NEW PHONE NUMBER OLD PHONE NUMBER
Inhibitory processes in memory? Suppression is an example of an inhibitory process Two paradigms based on idea of inhibition: Retrieval induced forgetting Think-no-Think paradigm Can we voluntarily repress certain thoughts or memories from our awareness?
Think-no-Think Paradigm Subjects studied pairs of weakly related words Recall and say aloud the response word no-think Or avoid thinking of the response word ( no-think condition) Recall of no-think words was impaired compared to respond pairs Anderson and Green (2001)