Poll 1

• The next slide is a photograph of an office.
• Look at it for 35 seconds. When it goes away, type everything you remember seeing in the office.

Poll 1: What Was in the Office?

Poll 2

• Twelve words will appear one at a time. Read each one and try to remember it.
• Do not write anything down.
• When the list ends, type every word you remember into the poll.

Poll 2: Which Words Do You Remember?

Schemas

• Schema: A general knowledge structure for “typical” events or situations.
  • General: encoded in a broad enough way that it helps you make predictions in similar situations.
  • Structured: includes many variables that are interdependent and affect your predictions as they change.
    • Ex: Getting ice cream. Price, flavor, and location are all part of the schema, but knowledge of one impacts your expectations of the others. An ice cream shop typically has more flavors and higher prices than Kroger.

How Schemas Help Memory

• A schema is top-down knowledge that tells you what to expect, so you can act in a new situation without working it out from scratch.
• At encoding, a schema decides what gets attention. The details that fit are processed quickly, and the details that do not fit stand out.
• At retrieval, a schema supplies retrieval cues. Remembering that you were at a restaurant brings back the menu, the server, and the check, because the schema links them.

Poll 1 Results

Poll 2 Results

How Schemas Sometimes Hurt Memory

• Retrieval rebuilds an event from two sources. The stored pieces of the event came in from the bottom up, and the schema that organizes them comes from the top down (Bottom-Up and Top-Down Processing).
• Where a piece is missing, the schema fills the gap with what is typical for that kind of event.
• The person cannot tell the two apart. A detail supplied by the schema feels the same as a detail that was stored.
• The poll results show which items and which words the class recalled. Some of them were in the office or on the list, but some were not.

The Office Study: Schemas at Retrieval

• Brewer and Treyens (1981): 30 people each waited alone for 35 seconds in the office you just saw, set up as a graduate student’s office, then were asked to recall everything in it.
  • Finding: Items that belong in an office schema, such as the desk and the chair, were recalled by 29 of the 30 people.
  • Finding: About a third of the people recalled books. There were no books in the room.

Intrusion Errors

• Intrusion error: When existing knowledge, such as a schema, or a memory of another experience is mistakenly included in a new memory.
  • Ex: The books in the office study. An office usually has books, so the schema added them.
• Every word on the list was linked to one word that was not on it: sleep. The results show how many of you recalled it.
• Reading twelve linked words activated the sleep node from twelve directions, and by the end of the list it was as active as the words that were shown.
• The books in the office and sleep on the list are the same error. The network supplied a detail that fit.

The Word-List Study: Intrusion Errors From Related Knowledge

• Roediger and McDermott (1995): College students heard lists of 12 words. Each list was related to one word that was never presented, and the sleep list you just saw was their first list. They then took recall and recognition tests.
  • Finding: People recalled the missing word on 40% of the lists, about as often as they recalled the words from the middle of a list.
  • Finding: On the recognition test, people said they had heard the missing word 84% of the time, about as often as they said it for words that were on the list (86%).

The Word-List Study, Continued

• Roediger and McDermott (1995), second experiment: The lists were lengthened to 15 words, and after the recognition test people said whether they remembered hearing each word or just found it familiar.
  • Finding: The missing word was recalled 55% of the time, and most people said they remembered hearing it.
  • Since then: Suarez and Beato (2021) list studies that found the same effect in English, Dutch, Spanish, Portuguese, French, Polish, Chinese, and Japanese.

Misinformation Errors

• Misinformation error: A memory error in which information encountered after an event changes what is recalled about the event.
• An intrusion error comes from inside: the person’s own schemas and memories fill a gap. A misinformation error comes from outside: someone else’s words, a news report, or a leading question about the event is stored as part of it.
  • Ex: A witness hears another witness say the car was red, and later remembers a red car.

The Car-Crash Study: Misinformation From a Question

• Loftus and Palmer (1974): College students in the US watched short films of car accidents and answered questions about them. One group was asked how fast the cars were going when they hit each other, and another group was asked how fast they were going when they smashed into each other.
  • Finding: The “hit” group estimated 34 mph, and the “smashed” group estimated 41 mph.
  • Finding: In a second experiment, 150 students came back a week later and answered ten yes-or-no questions about the film. One was “Did you see any broken glass?” There was none. 32% of the “smashed” group said yes, compared with 14% of the “hit” group and 12% of a group that had not been asked about speed.
• One word in a question, asked after the event, changed both the speed estimate and what people remembered seeing.

The Plane-Crash Study: Misinformation From News Reports

• Crombag, Wagenaar, and van Koppen (1996): Ten months after a cargo plane crashed into an apartment building in Amsterdam, Dutch adults were asked whether they had seen the television film of the plane hitting the building. No such film existed.
  • Finding: 55% in the first sample and 66% in the second said they had seen it, and many described details such as the angle of the plane.
• The crash was reported for weeks, with footage of the fire afterward. The reports supplied the event from outside, and the plane-crash schema supplied a video that was never filmed.

What Makes a False Memory Easier to Create

• Plausible details are easier to add than implausible ones. Broken glass fits a crash, but a helicopter does not.
• Adding to a memory is easier than replacing one. The glass was added to a crash that was really seen.
• Loftus and Pickrell (1995): 24 adults in the US read four short stories about their childhood, written with help from a relative. Three were true, and one, about being lost in a shopping mall at age five, was invented.
  • Finding: 6 of the 24 remembered the invented event, and some added details of their own.

Confidence and Accuracy

• People trust memories that are expressed with confidence, in themselves and in others. A confident witness convinces a jury.
• Confidence tracks how easily a memory comes to mind and how many times it has been retold, and neither one tracks whether the memory is accurate.
  • Ex: In the word-list study, people were as confident about sleep as about the words they had heard.
• Misinformation and intrusion errors are stored with the rest of the event, so they are retrieved with the same confidence as the details that were there.

Forgetting

• Most of what fails in memory is ordinary forgetting, which has two sources.
• Some forgetting is a failure of encoding. The information never entered long-term memory.
  • Ex: Forgetting the name of someone you met five minutes ago. Your attention was on what to say next, so the name never left working memory.
• The rest is a failure of retrieval. The information was stored, but the path to it has weakened with time.
  • Ex: Not remembering the material from a class you passed two years ago.
• An intrusion error adds a detail, a misinformation error changes one, and forgetting removes access to one without adding anything.

The Forgetting Curve

• Forgetting curve: A model of how memory declines sharply soon after learning and then levels off, unless the material is reviewed.
• Ebbinghaus (1913): He memorized lists of nonsense syllables, then relearned each list after a delay of 20 minutes to 31 days. His measure was savings, the percent of the original learning time that he did not need the second time. A list that took 10 minutes to learn and 4 minutes to relearn has 60% savings.
  • Finding: Savings were 58% after 20 minutes, 44% after one hour, 34% after one day, and 21% after 31 days. Most of the loss came in the first hour and the first day.

The Forgetting Curve Since Ebbinghaus

• Murre and Dros (2015) repeated Ebbinghaus’s method with one participant and found the same curve.
• Rubin and Wenzel (1996) fit 210 published forgetting data sets, from many kinds of material and many labs.
  • Finding: A few curve shapes, all steep at first and then flat, fit nearly all of the data sets.

The Forgetting Curve, Continued

• The curve levels off because the items lost first are the ones with the fewest links to other things in memory. The items still there after a day have more links, so they stay reachable.

Spaced Repetition

• Spaced repetition: A memory strategy that schedules reviews at progressively longer intervals to counter the forgetting curve.
• Cepeda et al. (2006): Combined 317 experiments that compared studying material in one session with studying it in sessions spread over time, with a test afterward.
  • Finding: Spaced sessions beat a single session in 259 of 271 comparisons, with 47% correct on the later test compared with 37%.

Spaced Repetition: The Gap Between Reviews

• In the same review, the gap between sessions that produced the highest test scores was longer when the test was further away.
• Cepeda et al. (2008): 1,354 people learned trivia facts, reviewed them once after a gap, and were tested one week to one year later.
  • Finding: For a test one week away, a gap of about one day worked best. For a test a year away, a gap of about three weeks worked best.

Spaced Repetition, Continued

• Each review resets the curve, and after each review the curve falls more slowly.

Spaced Repetition on Our Class Site

• The flashcards on our class site schedule reviews this way. A card you knew comes back after a longer gap, and a card you missed comes back sooner.
• One hour the night before an exam puts every review at the start of the curve, so most of it is gone within days, and little is left by next semester.
• Four 15-minute reviews on four different days are the same amount of study time, but each one happens where the curve is about to drop, so what they keep lasts through the exam and after it.
• Before Exam 1, most of the reviews on the class site happened on three days, and one of them was the night before the exam.

Memory and Emotion

• Emotional events are remembered better than neutral ones, for three reasons.

1. The amygdala responds to emotion, and its activity increases activity in the hippocampus, which stores the event more strongly (McGaugh, 2004).
2. People think and talk about emotional events more often, and each retelling is a retrieval that strengthens the memory.
3. Emotion narrows attention to a few parts of the scene, so those parts are encoded well and the rest is not.
   • Ex: Steblay (1992) combined 19 tests with 2,082 witnesses and found that witnesses who saw a weapon described the person holding it less accurately and picked that person out of a lineup less often.

Flashbulb Memories

• Flashbulb memory: Memory of the moment a person learned about a surprising, emotional event, recalled with unusual vividness and confidence but not unusual accuracy.
  • Ex: Where you were, who you were with, and what you did when you heard about the shooting on campus last December.
  • Ex: Where a person was on the morning of September 11, 2001, and who told them.
  • Ex: Where you were, who you were with, and how you reacted when you learned that your favorite team had won a championship.
• The memory is of the circumstances of hearing the news, and it feels like a photograph: the place, the people, the words, the weather.
• The event itself may have happened somewhere else, to someone else. The emotion is the person’s reaction to the news.

The September 11 Studies: Flashbulb Memory Errors

• Hirst et al. (2009): More than 3,000 adults in seven US cities described how they learned of the attacks one week afterward, then again after 11 months and 35 months.
  • Finding: After 11 months, 37% of the details in the accounts had changed, and after 35 months 43% had.
  • Finding: Confidence stayed high the whole time, at about 4.4 on a 5-point scale.
• Talarico and Rubin (2003): 54 students recorded a September 11 memory and an ordinary memory from the same week, then retold both up to 32 weeks later.
  • Finding: Both memories lost details at the same rate. Only the flashbulb memory kept its vividness and confidence.

Why Flashbulb Memories Change

• NOTE: Don’t confuse the September 11 studies with the plane-crash study. That study asked about the event (footage that never existed), and the error came from news reports. These studies asked about the person’s own morning, and the changes came from the person’s own retellings.

• Retelling is retrieval, and every retrieval rebuilds the memory from its pieces and the schema.

• People adjust a story for the listener, and the adjusted version is stored with the original.

• Other people’s accounts enter the memory, which is a misinformation error built up over years of conversation.

• Vividness comes from the emotion and the retellings. Accuracy depends on the same rebuilding as any other memory.

Traumatic Memories

• Traumatic memory: Memory of a frightening or harmful event that a person lived through, formed under intense stress.
  • Ex: A robbery victim’s memory of the robbery.
  • Ex: A soldier’s memory of an ambush.
  • Ex: A student’s memory of being there during the shooting on campus last December.
• Stress hormones released during the event strengthen the storage of what was attended to, so the center of a traumatic event is usually remembered (McGaugh, 2004).

Traumatic Memories, Continued

• The same narrowing that helps the center hurts the rest. Details outside the focus are encoded poorly, and the memory can come back in pieces.
• Head injury, sleep loss, and alcohol or drugs often accompany trauma, and each one interferes with encoding.

Flashbulb Memories and Traumatic Memories Compared

• The two terms name what the memory is of. A flashbulb memory is of learning the news. A traumatic memory is of an event the person lived through (Talarico, 2023).
• The terms do not rank how upsetting a memory is, and neither one depends on stress hormones alone. Both kinds are stored with the help of the amygdala (McGaugh, 2004).
• One person can have both from one event. A student who was at the scene of the shooting last December has a traumatic memory of it, and also a memory of learning, later that day, who had been hurt.
• Hearing the news or watching video of it can be traumatic in its own right. After the Boston Marathon bombing, people who watched six or more hours of coverage a day reported more acute stress than people who had been at the bombing (Holman et al., 2014).

Flashbulb Memories and Traumatic Memories Compared, Continued

• Neisser et al. (1996): Californians who lived through the 1989 Loma Prieta earthquake and Atlanta students who heard about it recalled the day shortly afterward and again 18 months later.
  • Finding: The Californians’ memories of what happened to them were nearly perfect at 18 months. The Atlantans’ memories of hearing the news had changed much more.
• Sharot et al. (2007): Three years after September 11, New Yorkers recalled that day while their brains were scanned.
  • Finding: People who had been in downtown Manhattan, near the towers, showed amygdala activity while recalling the day. People who had been a few miles away did not.
• Both kinds of memory are vivid and held with confidence. Neither is exempt from the errors in this deck.

Recovered Memories?

• Some clinicians claim that a traumatic memory can be repressed for years and then recovered in therapy.
• Otgaar et al. (2019): Researchers reviewed the studies on repressed and recovered memories.
  • Finding: Complete loss of memory for a trauma is rare among trauma victims. Cases described as recovered memories are better explained by ordinary forgetting, by memories that were never lost but not talked about, or by false memories created during therapy.
  • Finding: Hypnosis, guided imagery, and repeated suggestive questioning create false memories of events that did not happen.
• A memory created by a therapist’s questions is a misinformation error. The information came from outside, after the event, and was stored as part of it.

Memory and the Self

• Memories about ourselves are rebuilt the same way as every other memory in this deck: from stored pieces, with a schema filling the gaps. Here the schema is of who we are.
• That schema favors consistency, so past feelings tend to be remembered as closer to present feelings than they were.
• Levine (1997): Supporters of Ross Perot rated how they felt when he dropped out of the 1992 presidential race in July. After the November election, they recalled those July feelings and rated how they felt about him now.
  • Finding: The recalled July feelings matched each person’s November view of Perot better than they matched what the same person had reported in July.

The Tradeoff Behind Memory Errors and Forgetting

• The errors in this deck and ordinary forgetting come from one design: memory is a network, and retrieval rebuilds an event from linked pieces and a schema.
• A schema lets a system with Limited Capacity handle a familiar situation without processing every detail. Filling a gap is that same process, applied to a memory.
• Forgetting clears what has not been needed. Information that has gone unused for a while is unlikely to be needed again, and the forgetting curve follows that pattern (Anderson and Schooler, 1991).
• A specific error can be corrected. Seeing the office photograph again stores the room without the books. The process that produced the error stays, because it is what makes memory useful (Schacter, 1999).
• Emotion strengthens what mattered most at the time, and that same strengthening makes the memory feel more accurate than it is.