Retrieval and Interference
• There are many plausible reasons to account for the normal forgetting of information
– Interference
– Decay – the memory is subject to the
combined effects of time and interference – Loss of retrieval cues
Interference • Role of interference
– Part of the difficulty for Ebbinghaus may have been the fact that he memorized so many lists of nonsense syllables.
– If an individual learns several sets of related materials, the retention of the old material
makes it harder to retain new material, and the learning of the new materials makes it harder to retain the old.
Interference • The role of interference
– If retaining old material makes it hard to recall new material, it is proactive interference.
– If learning new material makes it hard to recall old material, it is retroactive interference.
– Ebbinghaus had memorized so many lists of nonsense syllabus that he experienced a
Concept Check
You answer the telephone at your new receptionist job with the name of the your former employer’s
firm. What kind of interference caused this embarrassing slip-up?
Reconstructing Past Events
• When you try to remember an event, you usually start with details you remember clearly, and fill in the gaps.
• This is the process of reconstruction. During an event, we construct a memory. When we try to retrieve the memory, we reconstruct an account based partly on surviving memories and partly on expectations of what must have happened.
Reconstructing Past Events
• Your memory for activities that are routine – your breakfast, lunch or dinner for example – from the past week can be reconstructed with little effort. But these will fade rapidly unless something
Reconstructing Past Events
• If your family all got sick after one meal, you will probably remember that meal in better detail for much longer than is usual.
• If you met a new love interest when you were out to dinner with friends, this event will also be more memorable and easily reconstructed.
• However, you may fill in missing details with
typical activities associated in your memory with routine meals at home or dining out.
Reconstructing Past Events
• We will add words to lists that we’ve heard or read depending on what content we believe would have been on the list, based on its
apparent theme.
• The less certain of our memories that we are, the more we will rely on our expectations.
Reconstructing Past Events • Hindsight bias
– Hindsight bias is the tendency to mold our recollection of the past to how events later turned out.
• We say “I knew that was going to happen!” after the event has occurred.
• Our memories are tailored as we
Reconstructing Past Events
• The “false” or “recovered” memory controversy
– Reports of long-lost memories, prompted by clinical techniques, are known as recovered memories.
Often these are memories of abuse that took place in early childhood.
– There have been examples of accurate and
inaccurate memories constructed through clinical techniques.
– Psychological researchers want to know if it is likely that people will forget abusive or traumatic
Reconstructing Past Events • Memory for traumatic events
– Sigmund Freud believed that it was possible to repress a painful memory, motivation or
emotion, to move it from the conscious to the unconscious mind.
– This idea is not well supported in research on memory and forgetting.
Reconstructing Past Events • Memory for traumatic events
– Research indicates that it is possible to forget a traumatic event, but whether this happens depends on a number of factors – age at the time of the event, reaction of family, and type of event.
– Most people do not forget traumatic events if they happen later than age 3.
Reconstructing Past Events
• Memory for traumatic events
– Whether this happens because of repression or normal forgetting is unclear. People forget neutral or joyful events from early childhood as well.
– Repression of traumatic events does not fit with our understanding of the biological process of storing memory.
– Emotional stimulation releases cortisol. The net effect is to improve the storage of memory.
Reconstructing Past Events
• Suggestion and false memory
– A false memory is a report that an individual believes to be a memory but actually never occurred.
• Various studies have shown that it is possible by suggestion to implant memories for fictional
events.
• About a quarter of subjects in several studies were convinced that they had been lost as
Reconstructing Past Events • Suggestion and false memory
– Plausible events were more likely to be remembered, and the memories were
somewhat vague, but these results were achieved after a single, brief suggestion.
– Similarly, memory for details after watching a videotaped event can be altered or distorted by the use of leading questions.
Reconstructing Past Events • Children as eyewitnesses
– Research with children can be ethically difficult because of their vulnerability. – Children forget rapidly and sometimes
confuse fantasy and reality, but sometimes children witness crimes or other events about which we need information.
– How do we work with children to tap their memories accurately? Can we do this?
Reconstructing Past Events • Children as eyewitnesses
– Under proper conditions, children as young as three can make accurate reports of events
that they have witnessed.
• Young children can answer specific questions accurately.
Reconstructing Past Events • Children as eyewitnesses
• A delay between the event and the
questioning is likely to result in the child giving incorrect information.
• If the child can’t understand the question he or she is more likely to give incorrect
Reconstructing Past Events
• Children as eyewitnesses
– Repetition of the question in the same interview session may yield two different answers.
– Repetition of the question between spaced
interview sessions may help the child remember better, which is important in court testimony.
– Dolls and props seem like helpful tools, but they do not increase the accuracy of a child’s recall or testimony.
Reconstructing Past Events • Children as eyewitnesses
– The most effective strategies in interviewing young children are:
• Use of simple questions
• Maintenance of a non-threatening atmosphere during the interview
• Avoidance of suggestions or pressure • Schedule the interview as soon as is
True, False, Maybe
• Memories may or may not be reliable.
• There is much evidence of forgetting and
distortion. We use adaptive strategies for “filling in the gaps” – reason and logic.
• It is prudent to always consider the possibility that a seemingly clear memory is distorted or false.
Module 7.4 • Amnesia
Amnesia After Brain Damage
• Amnesia is a severe loss or deterioration of memory.
• We can learn a lot about the different forms of memory by studying these cases.
Amnesia After Brain Damage • “H.M.”
– In 1953, “H.M.” had his hippocampus and surrounding areas of the temporal lobes removed to control his intractable seizures.
– Although his seizures decreased dramatically, he experienced such severe memory
impairment that the surgeon vowed that he’d never again attempt such a procedure.
Figure 7.19a
Amnesia After Brain Damage • “H.M.”
– He had massive anterograde amnesia. He was unable to store any new memories. (It was 1953 for the rest of his life.)
– He had moderate retrograde amnesia. He
could not remember many events that occurred between 1 and 3 years before his surgery.
– He did retain normal short-term memory functions and procedural memory.
Figure 7.20
Figure 7.20 Brain damage induces retrograde amnesia (loss of old memories) and anterograde amnesia (difficulty storing new memories.)
Amnesia After Brain Damage • “H.M.”
– What has been learned about the
hippocampus from H.M.’s tragic story?
• Other things being equal, the more difficult a memory task is, the more it depends on the proper functioning of the hippocampus. • The hippocampus is important for
Amnesia After Brain Damage • Frontal-lobe damage
– The frontal lobes receive substantial input from the hippocampus. Damage to the frontal lobes causes some problems that are similar to
hippocampal damage, and some unique problems as well.
– Frontal lobe damage occurs as a result of
stroke, head trauma, or Korsakoff’s syndrome, a dementia brought on by deficiency of vitamin B1 related to chronic alcoholism.
Amnesia After Brain Damage • Frontal-lobe damage
– The deficiency leads to loss and shrinkage of neurons in many parts of the brain, especially the thalamus and prefrontal cortex.
– Multiple impairments of memory can result from this deterioration.
Amnesia After Brain Damage • Frontal-lobe damage
– Typical symptoms of Korsakoff’s syndrome include –
• Apathy and confusion
• Retrograde amnesia – usually dating back to about 15 years before the onset of the
syndrome
• Anterograde amnesia
• Confabulation – wild guessing mixed in with correct information in an effort to hide
Amnesia After Brain Damage • Implicit memory in amnesiac patients
– Recall these two divisions of long-term memory:
• Explicit memory involves the recall of
knowledge and events in which a person deliberately retrieves the answer and
recognizes it as a correct one.
–Your instructor asks you to name two psychologists associated with the
Amnesia After Brain Damage • Implicit memory in amnesiac patients
– Implicit memory does not require recognition. The recall of activities stored in implicit
memory seems effortless and unconscious. • You drive your car to school everyday but
don’t remember any details of the activities associated with driving.
Amnesia After Brain Damage • Implicit memory in amnesiac patients
– Amnesiac patients such as H.M. show normal ability to use and store new implicit memory, but have impaired functioning of the factual memory activities of explicit memory.
Amnesia After Brain Damage • Implicit memory in amnesiac patients
– NOR____ – DET____ – COR____ – FRO____
Amnesia After Brain Damage
• Implicit memory in amnesiac patients
– If you wrote any of the following – normal, detail, correct or cortex, frontal, there is a good chance that you were recalling words that appeared in the slides that preceded the task. It will be easy for you to remember this now that you know what
happened.
– Amnesiac patients will perform similarly on this task – called “priming” – they will complete the words in a similar manner, but not remember having read them previously.
Amnesia After Brain Damage • Implicit memory in amnesic patients
– It is not uncommon for such a patient to learn a video game or other procedural task
perfectly. However, the patient will never remember the event of being taught the
game, or any individual session of playing it, even if that patient becomes highly skilled at the actual playing!
Concept Check
You have learned to play the guitar. What type of memory is involved in playing a song for your
friends?
Concept Check
You play guitar at a party for your friends. Later you remember the good time you had playing for them. What type of memory is involved in
remembering this?
Concept Check
• Which of the following is an example of implicit memory?
a. There is a soap opera on TV at home. You don’t get to watch it often, so you can never tell your friends the names of the characters. Two days later you are watching a late night TV
program and you recognize one of the leading men as a guest.
Concept Check
• Which of the following is an example of implicit memory?
• b. You are sitting behind a couple at the movies who are having an animated discussion about
skydiving. You are not paying attention to the content of their discussion. Later you
spontaneously comment to your friends about how much fun it would be to learn to skydive. “ b” is implicit memory
Concept Check
What kinds of memory are most impaired in
frontal lobe dementia patients and patients like H.M.? What kinds are least impaired?
Declarative or explicit memories are most impaired. Procedural or implicit memories are least impaired.
Alzheimer’s Disease
• Most healthy people show little decline of memory in old age
– A common cause of decline in older people
and a few middle aged persons is Alzheimer’s disease.
– About 99% of cases are late onset.
– The disease is marked by a gradual build-up of harmful proteins and deteriorating brain cells.
Alzheimer’s Disease
• Both anterograde and retrograde amnesias result from this build-up
– Arousal and attention are impaired.
– Skills and implicit memory may remain intact for some time.
Amnesia of Old Age
• People would like to know how to increase the chance of having good memory function later in life:
– A healthy lifestyle with regular exercise, good diet, and limited use of alcohol has been
shown to help.
– An intellectually stimulating life may be related to good memory function as well.
Infant Amnesia
• Few people can remember events earlier than age 5 or 6. Though children younger than this can describe earlier events in their own lives, these memories tend to fade.
• The scarcity of early declarative memory is called infant amnesia or childhood amnesia. Why does this happen?
Infant Amnesia
• Freud believed that this was a result of
repression due to the emotional traumas of
infancy. He offered no evidence for this theory. • Some cognitive psychologists believe that this is
because early memories are nonverbal and later memories are verbal.
• A biological explanation is that the hippocampus is not fully developed and doesn’t store
Infant Amnesia
• Another cognitive explanation is that lasting memories require a sense of self, and this
typically doesn’t develop fully until between 3 and 4 years of age.
• The theory of encoding specificity suggests that our retrieval cues in later life may not be
adequate to recall early memories.
• We are still trying to understand why these memories are not accessible.
Amnesia of Old Age
• Some older people suffer from Alzheimer’s and other dementias that impair attention and
memory.
• Up until recently, scientists have typically overstated the vulnerability of healthy older people to memory loss.
Why do we forget?
• Catastrophic loss of memory can only result from brain damage or disease.
• “Normal” forgetting is a product of mechanisms that are usually adaptive.
• It is probably true that remembering everything that happened would be overwhelming and