10: Forgetting & Reconstruction

Are there limits to memory capacity? #

Memory experts #

  • Rajan Mahadevan memorized .$\pi$ to over 30,000 digit in 3 hours, 45 minutes; father had memorized all of Shakespeare’s sonnets
    • Subconsciously done and primarily for numbers
  • Russian journalist Shereshevskii “recalled everything he had ever seen or heard”
    • Could report back 70 digits or words after only having heard them once
    • Could recall list and circumstances under which he had learned it 15 years later
    • Potentially first (recorded) case of Hyperthymesia
  • Drawbacks of having a “perfect” memory
    • Rajan: “As a child, I used to be so lost in my own thoughts, I would talk to myself. It was hard to fit in. Other kids didn’t know what to make of me.”
    • Shereshevskii: ultimately, unable to distinguish between conversations he’d heard 5 minutes or 5 years before, he ended up in an asylum
    • Memory whizzes are often poor at abstract thinking – generalizing, organizing, evaluating

Savant Syndrome and Memory #

Savant syndrome: people who are born with severe intellectual disability but show superior ability in one intellectual domain, such as music, art, or mental arithmetic

  • About 10% of children with autism have savant talents
  • Analysis of case history of 13 musical savants
    • All had severe deficits in ability to understand and use language
    • 5 were blind or partially so
    • All showed an extraordinarily intense interest in performing music beginning at a very young age, usually before age 4 (Treffert, 2008)
  • Savant syndrome is largely attributable to a seemingly limitless memory
    • Artistic savants can reproduce exact copies of animals or people or scenes from memory
    • Musical savants can play back, note for note, long passages of music heard just once

    • Human calculators can tell you the day of the week that corresponds with any given day of any given month and year, past or future
    • Suggests that memory capacities are potentially virtually limitless…
  • Possible to create savant-like memorization skills and artistic abilities in people without autistic traits by disrupting left anterior frontal lobe with TMS
    • OG Rainman, Kim Peek, didn’t have two separate hemispheres (no interference) – could read two pages at once

Neurocognitive Model of Savant Syndrome #

  • Savant syndrome is associated with
    • Disruption of global connectivity in neural networks, which results in impairment in certain types of cognitive processing, such as executive function and social cognition
      • Less global and more local focus
    • Enhanced connectivity in local brain regions (in part through disruption of connections to prefrontal cortex, which exerts inhibitory control on other cortical regions), resulting in specialization and facilitation of low-level cognitive processing

Feats of memory in ordinary people #

  • Participants were shown 2500 slides of faces and places for 10 sec each
    • Afterwards, they were able to pick out slides they had seen with 90% accuracy (Standing, Conezio, Haber, 1970)
  • People can remember a substantial amount of material learned decades earlier, including foreign language vocabulary, mathematical knowledge, and information from a psychology course
    • May not be able to produce information without stimuli (hint)

Three stages of memory processing and forgetting #

Memory as an information processing system:

Encoding failure #

Encoding failure: information never entered long-term memory (lack of attention)

  • Memory of penny:
  • You must have seen the Apple logo thousands of times; Can you draw it?
    • Only 1 in 85 UCLA students, including 52 Apple users, could accurately draw the Apple logo (Blake, Nazarian, & Castel, 2014)

Storage decay #

Storage decay: information stored in long-term memory gradually fades

  • In general, storage decay is not as severe as most people tend to think…
    • Study found that people remembered nearly 40% of foreign language vocabulary, idioms, and grammar after 50 years (and 75% when recognition tests are used)
    • People who had taken psychology class remembered about 70% of broad general facts and research methods 10 years later (Bahrick, Bahrick, & Wittinger, 1975)

Role of interference #

Is storage decay simply due to the passage of time or to interference from new memories formed during this interval? Research suggests that storage decay is primarily due to interference

  • Participants learned lists of nonsense syllables, then either slept or engaged in normal daily activities
    • Recall was significantly better when participants slept during the retention interval (Jenkins & Dallenbach, 1924)
  • The degree to which memories interfere with each other depends on their similarity
    • Study subjects intermittently
    • It’s harder to remember a list of letters if all the letters rhyme (V, G, P, D)

Retrieval failure #

Retrieval failure: failure to access information that is stored in long-term memory – “forgotten” material is not completely erased but merely inaccessible

Research on cuing #

  • Evidence for retrieval failure
    • Willem Wagenaar (1986), a Dutch psychologist kept a diary in which he recorded one or two of his experiences every day for six years, resulting in a total of over 2400 incidents
    • He tested his memory by having a colleague supply some information from each diary entry, then seeing if he could recall the remainder
    • With a sufficient number of cues, he was able to recall virtually every incident that he had recorded over those six years

Savings during relearning #

  • Research using digit-word pairs has found that even when information appears to have been entirely forgotten (can neither be recalled or recognized), the information can be relearned much more rapidly the second time around
    • Even in the case of material that has apparently been “forgotten” , some memory trace is preserved
  • In addition, even if you can’t actively recall material, it may still be present in your brain in some form and may affect you in various ways

    Education is what survives when what has been learned has been forgotten" – B.F. Skinner

TOT phenomenon #

Tip-of-the-tongue (TOT) phenomenon: sensation we have when we are confident that we know the word for which we are searching yet cannot recall it

  • “The signs of it were unmistakable; he would appear to be in mild torment, something like the brink of a sneeze, and if he found the word his relief was considerable”
  • This subjective feeling of knowing strongly suggests that the forgotten material is really still there, but is this feeling trustworthy?
  • Research suggests that it is
    • Even when people cannot remember the word for which they are searching, they often can identify important attributes such as the first letter, the number of syllables, and (in Romance languages) the grammatical gender of a noun
    • Providing first letter or number of syllables of target word may prompt recall

Causes of retrieval failure #

  • Lack of appropriate retrieval cues (due to encoding specificity principle)
    • Ex: Inability to recognize student from your biology class at a dorm party
  • Context effect: you walk into kitchen to get something, but forget; returning back into the original room, you recall again!
  • Repression of painful or anxiety-provoking information
    • There have been documented cases of individuals who had been treated in hospital emergency rooms for childhood sexual abuse, yet these individuals failed to recall the episode when interviewed as adults (Williams, L.M., 1994; Schooler, Bendiksen, & Ambadar, 1997)

Are Encoded Memories Ever Forgotten? #

  • Difficult, if not impossible to prove, but the bulk of research evidence suggest that memories are never completely forgotten – they are still present in some form though they may be inaccessible

Memory and Forgetting in Children #

  • Babies only 3 months old can learn that kicking moves a mobile – and retain that learning for a month
  • However, adults generally can’t remember events that occurred before 2 or 3 years of age – infantile amnesia
    • College students recalled details of birth of younger sibling much more accurately if they were three-years-old at the time of the sibling’s birth than if they were two-years-old (Usher & Neisser, 1993)
    • Recall is poorer if a dramatic change in childhood environment occurred (moving to a different country) or if language spoken changed
    • Two contributing factors:
      • We index much of our explicit memory with a command of language that young children do not possess
      • The hippocampus is one of the last brain structures to mature, and as it does, more gets retained (Akers, Martinez-Canabal, Restivo et al., 2014)
  • Study found that 10-year-olds could consciously recognize (amid other photos) only 1 in 5 of their former preschool classmates
    • However, their physiological responding (skin perspiration) was greater when shown their former classmates – even when not consciously recognized (Newcombe, Drummey, Fox et al., 2000)

    You have been mine before,
    How long ago I may not know:
    But just when at that swallow’s soar
    Your neck turned so,
    – Dante Gabriel Rossetti

Memory Reconstruction #

Memory as reconstruction: what we think we remember often never really occurred – we filter information and fill in missing pieces

Reconsolidation #

Reconsolidation: Whenever we retrieve a memory, the brain rewrites it a bit – it is slightly altered chemically by a new protein synthesis that links it to our present concerns and understanding

  • Every thought we think rewires our brain to some extent, changing its structure and/or function
  • Because the processes involved in memory reconstruction are unconscious, we can be convinced that our memories are accurate even when they are partially or even wholly wrong (Offer, Kaiz, Howard et al., 2000)
  • 73 ninth-grade boys were interviewed, then reinterviewed 35 years later
    • When asked to recall how they had reported their attitudes, activities, and experiences, most men performed at a rate no better than chance
    • 1 in 3 now remembered having received physical punishment though, as ninthgraders, 82% said they had
  • Researchers are experimenting with manipulating reconsolidation to treat people with traumatic memories
    • People are asked to recall the traumatic or negative experience
    • At the same time, they are given
      • Propranolol, a memory-blocking drug or
      • A brief painless electric shock
    • This disrupts reconsolidation of the memory, “erasing” it in part
    • Treatment still in experimental stages at this point

Causes of Memory Distortions #

Consistency bias #

Consistency Bias (or hindsight bias): we tend to reconstruct the past to be more consistent with our current feelings and beliefs

  • People asked how they felt 10 years ago about marijuana or gender issues recalled attitudes closer to their current views than to the views they had actually reported a decade earlier (Markus, 1986; Mazzoni & Vannucci, 2007)
  • Couples who were re-interviewed after eight months remembered their past feelings about their partners as matching their current feelings more than had actually been the case (McFarland & Ross, 1987)

Schemas #

Schemas: generalized information about a situation or event (e.g., things people do at birthday parties)

  • In general, people show enhanced recall for schema-consistent material but there are exceptions

Repisodic memory #

Repisodic memory: recall of a supposed event that is really the blending of details over repeated and related episodes

  • If asked to recall the details of last Monday’s lunch, you might produce a repisodic memory based on what you usually do for lunch

Misinformation effect #

Misinformation effect: incorporating misleading information presented after an event into one’s memory of the event

  • Study in which people were shown a film depicting a traffic accident, then either asked how fast the cars were going when they hit each other or how fast they were going when they smashed into each other
    • People gave faster speed estimates when word smashed was used
    • When asked a week later whether there was any broken glass in the accident, people who heard ‘smashed’ were much more like to answer yes (Loftus & Palmer, 1974)

Source amnesia #

Source amnesia: attributing to the wrong source an event that we have experienced, heard about, read about, or imagined

  • Case of Donald Thomson, a psychologist studying memory who was accused of rape after being interviewed on live television
  • Photo lineup studies
    • Participants watched a staged crime, then examined mug shots to identify the perpetrator
    • A few days later, they were asked to identify perpetrator in a lineup
    • Participants revealed a strong tendency to select people whose faces had been seen only in the mug shots

Implantation of false memories #

  • Studies show that it’s not all that hard to plant a false memory in a person’s mind
    • Participants in one study were falsely led to “recall” that they had knocked over a punch bowl at a wedding when they were six-years-old (Hyman, Husband, & Billings, 1995)
    • In a more recent study, 70% of students reported a detailed false memory of having committed a crime, such as assaulting someone with a weapon (Shaw & Porter, 2015)
  • Memories are particularly easy to implant if person is asked to visualize event

Overconfidence in flashbulb memories #

  • Overconfidence in flashbulb memories (memory for the situation in which you first learned a very surprising and emotionally arousing event)
    • People were interviewed one day after the explosion of the space shuttle Challenger and again, three years later
      • Participants reported having vivid memories of what they had been doing when they heard the news and were very confident that their memories were accurate
      • However, these recollections were often wrong! Average accuracy score was only 3 on a 7-point scale, and 25% of participants were wrong on every single detail (Neisser & Harsh, 1992)
    • Flashbulb memories are typically no more accurate than memories for other events – people’s confidence in their testimony is not strongly correlated with accuracy

Eyewitness Testimony #

How accurate are our memories?

  • On the one hand, our memories can be remarkably accurate
  • On the other hand, our memories are far from perfect

Eyewitness testimony is often mistaken #

  • It is estimated that 2000 to 10,000 people are wrongfully convicted each year in the U.S. on the basis of eyewitness testimony
  • Case of man who spent 11 years in prison for rape before they found out on the basis of DNA testing that he couldn’t have been the assailant
  • One study examined 62 cases in which innocent people were later exonerated on the basis of DNA evidence (including 8 in which person had been sentenced to death)
    • In 52 of these 62 cases, the crucial evidence leading to conviction had come from eyewitnesses (Scheck, Neufield, & Dwyer, 2000)
    • Dilema: Eyewitness testimony is also the #1 factor that leads to conviction too

Factors affecting accuracy #

  • Errors are especially likely if:
    • Witness’ attention was stressed and/or distracted (e.g., by presence of a gun)
    • Plausible misinformation was given during questioning
    • Witness is pressured to give a specific response
    • Witness is given positive feedback (could be even a simple “OK”)
    • Confidence of a witness is a very poor predictor of whether a memory is accurate; nevertheless juries are strongly influenced by confidence (Busey, Tunnicliff, Loftus et al., 2000)

Face recognition #

  • Experiment: Picture, in your mind, a stranger whom you’ve seen recently (e.g., waiter or waitress who served you recently or the person who sat next to you on the bus)

    • Do you think you could pick that person out of a police lineup?
    • What if I first asked you to write down in as much detail as you can about what that person looks like? Do you think this will improve or impair your ability to pick that face out of a lineup?
      • Answer: Impair

    • Attempt to verbalize memories/insights may in fact impair your ability to recall what was actually there (Dodson, Johnson, & Schooler, 1997)
  • Experiment: Participants are shown series of faces and asked to make either

    • Holistic judgments (Does she look like an accountant?) OR
    • Judgments about specific features (Does he have bushy eyebrows?)
      • Which condition resulted in better performance on recognition test?
      • Answer: The holistic judgments condition (Baddeley, 1979)

    • Expert police sketch artist focus on asking witness about emotional characteristics of suspect in sketching portrait (Jonathan Schooler)

Own-ethnicity bias #

Own-race bias or other race effect: People are more accurate in identifying members of their own race

  • Analyses of people’s descriptions of faces for police artist show that people tend to describe members of their own race more in terms of emotions or personality characteristics
  • Effect seems to be primarily due to experience
    • People of European descent more accurately identify individual African faces if they have watched a great deal of basketball on television, exposing them to many African-heritage faces (Li, Dunning, & Malpass, 1998)

Improving Testimony #

  • Warn witness that perpetrator might not be present
    • Witnesses are often convinced that culprit must be present in a lineup and so simply pick the person who most closely resembles their memory of the perpetrator
      • Researchers found that telling witnesses that perpetrator might not be present reduced number of innocent people who were identified incorrectly by 42%

Cognitive interview technique #

  • Cognitive interview technique: Ask witness to describe what happened before beginning questioning
    • Reinstate physical and emotional context of the crime as fully as possible, e.g., by returning to the scene of the crime for the interview
    • Ask witnesses to visualize scene and describe every detail before detective begins questioning
    • Technique has generally been found to result in recall of 30% to 35% more information without any increase in erroneous recall
  • Ask witness open-ended questions

Recovered Memories #

Much of the recovered memory literature has focused on cases of child abuse

Real memories #

  • Research has demonstrated that some people may indeed forget about painful childhood memories and recall it years later
    • There have been documented cases of individuals who had been treated in hospital emergency rooms for childhood sexual abuse, yet these individuals failed to recall the episode when interviewed as adults (Williams, L.M., 1994; Schooler, Bendiksen, & Ambadar, 1997)
    • Case of a college professor, Ross Cheit, who woke up one morning and suddenly remember having been molested by camp counselor – counselor confessed when confronted with the crime (Schacter, 1996)

False memories #

  • Many reported incidences of abuse probably never happened
  • Research has shown that it is not all that hard to implant false memories
    • Study on implanting false memories in children (Ceci, 1995)
    • An adult repeatedly asked child to think about several real and fictitious events

      “Think hard, and tell me if this ever happened to you. Can you remember going to the hospital with a mousetrap on your finger?”

    • After 10 weeks, a new adult asked the same question
    • 58% of preschoolers produced false (and often vivid) stories regarding one or more events they had never experienced
      • When reminded that his parents had told him several times that the mousetrap incident never happened – that he had imagined it, child protested, “But it really did happen. I remember it!” (Weiten, W., 1998)
  • Children have particular difficulty with source monitoring
    • Ex: they sometimes recall that they had performed a task that someone else had actually performed
  • According to Freud, children’s attention tend to be focused on erogenous zones
    • 3-year-olds were asked to show on anatomically correct dolls where pediatrician had touched them
    • 55% who had not received genital examinations pointed to either genital or anal areas (Ceci & Bruck, 1993, 1995)

Children’s Eyewitness Testimony #

  • Under ideal circumstances, children’s reports can be trustworthy
  • Reports may be unreliable when
    • Children are young
    • They have been supplied with suggestive questions
    • Interviewers ask questions in a highly emotional tone or use complex language (Pipe, Lamb, Orbach et al., 2004)
  • Nine-year-old girl said she had seen suspect with blood spattered on his shirt and hands
    • Two weeks before scheduled execution, girl admitted that she wasn’t certain whether the red stain was blood or salsa (suspect had worked in a salsa factory)
    • She said that she had originally testified against man because her mother had told her that he was a bad man, and people encouraged her to be more certain of her testimony than she was (Ceci & Bruck, 1995)

Déjà Vu #

  • Who experiences déjà vu?
    • About 60% of population
    • Negatively correlated with age
    • Positively correlated with socioeconomic level and education
    • Positively correlated with stress and fatigue
    • More common in people who travel
  • Scientific explanations (Alan S. Brown, 2003):
    • Dual processing explanation
      • Incoming sensory data follow several different pathways
      • A slight alteration in transmission speed in one pathway could cause the brain to interpret the data as two separate experiences
    • Attentional explanation
      • A fully processed perceptual experience that matches a minimally processed impression received moments earlier produces a strong feeling of familiarity
      • The original impression may not have been fully processed due to a physical distraction or a mental distraction, such as preoccupation with other thoughts
    • Memory explanation:
      • Implicit familiarity without explicit recollection
      • Ex: Seeing a lamp in your friend’s apartment that is similar or identical to one that used to be in your aunt’s house