Chapter 7Retention & Retrieval

Remembering & Forgetting

Levels of Processing Model• Retention depends upon how deeply information is

processed

• The shallowest levels of processing occur when the person is merely aware of the incoming sensory information.

• Deeper processing takes place only when the person does something with the information– Makes associations– Attaches meaning– Actively elaborates

Memory Retrieval Varies in Difficulty

RecallSerial recallFree recallRetrieval cue

Recognition – hippocampus

Relearning - savings

Context Effects Improve Retrieval

• Many elements of the physical setting in which we learn information are simultaneously encoded into long-term memory.

• Those stimuli or similar stimuli will allow us to more easily recall information from long-term memory

• These stimuli appear to serve as retrieval cues.

Context Effects

– memory works better in the context of original learning

– Good reason for coming to class

– Holidays

Context Effects

0

10

20

30

40

Water/land

Land/water

Water/water

Different contexts for hearing and recall

Same contexts for hearing and recall

Land/land

Percentage ofwords recalled

Psychological Retrieval Cues• Our internal psychological environment can also

be encoded and become part of our memory strands.

• State-dependent memory: – The tendency for retrieval from memory being

better when our state of mind during retrieval matches our state during encoding.

– Mood-dependent memory

Encoding Specificity Principle

–Encoding specificity principle: a retrieval rule stating that retrieving information from long-term memory is most likely when the conditions at retrieval closely match the conditions present during the original learning

Reconstruction of Memory

• Elizabeth Loftus– What a person usually recalls is not a replica,

but a reconstruction of the event

– A reconstruction is an account which is pieced together from a few highlights, using information which may or may not be accurate.

Memories Are Reconstructions of the Past • The scientific belief in the reconstructive nature of

memory was first proposed in the 1930s by Sir Frederic Bartlett.

– By testing people’s memories of stories they had read, Bartlett found that accurate recollections were rare.

– Errors increased over time.

Memories Are Often Sketchy Reconstructions of the Past

• Bartlett concluded that –

The parts that participants were most confident of remembering were often those that they had created.

People systematically distort details (facts and circumstances).

People are largely unaware they have reconstructed the past, and

Information already stored in memory strongly influences how new information will be remembered.

Memories are Affected by Schemas

• Schemas are integrated frameworks of knowledge and assumptions a person has about people, objects and events.

• They influence what people notice and how they encode and recall information.

• In other words, we distort new information to fit our existing schemas.

Memories Are Affected by the Introduction of Inaccurate Information

• Misinformation effects: distortions and alterations in people’s memories due to them receiving misleading information during questioning

Depiction of actual accident

Leading question:“About how fast were the carsgoing when they smashed intoeach other?”

Memoryconstruction

Misinformation EffectEyewitnesses

reconstruct memories when questioned

Amnesia

• Retrograde amnesia: loss of memory from the point of some injury or trauma backwards, or loss of memory for the past

• Anterograde amnesia: loss of memory from the point of injury or trauma forward, or the inability to form new long-term memories (“senile dementia”); see the case of H.M.

LO 6.12 How Does Amnesia Occur?

Amnesia

• Infantile amnesia: the inability to retrieve memories from much before age three– autobiographical memory: the memory for

events and facts related to one’s personal life story (usually after age three)

Source amnesia

LO 6.12 How Does Amnesia Occur?

Alzheimer’s Disease

• The primary memory difficulty in Alzheimer’s is anterograde amnesia, although retrograde amnesia can also occur as the disease progresses.

• There are various drugs in use or in development for use in slowing or stopping the progression of Alzheimer’s disease.

LO 6.13 What Are the Facts about Alzheimer’s Disease?

Source Confusions Can Create Memory Illusions

• Sometimes we forget the true source of an episodic memory and may experience a memory illusion.

• Memory illusions appear to be shaped by implicit remembering.

Source Confusions Can Create Memory Illusions

– Common types of memory illusion include:

• Déjà vu: a memory illusion in which people feel a sense of familiarity in a situation that they know they have never encountered before

• Cryptomnesia: (hidden or forgotten memory) a memory illusion in which people believe that some work they have done is a novel creation, when, in fact, it is not original

Forgetting

Most Forgetting Occurs Soon after Learning

• Much of what a person learns is quickly forgotten. – Herman Ebbinghaus’s research (1800s)

• Most forgetting occurred within 9 hours after learning. • Everything about it may not be forgotten.

• Implication: most forgetting is not complete.– One reason for forgetting (encoding failure):

• Not being sufficiently attentive when information is presented

Ebbinghaus’s Forgetting Curve

Forgetting: Encoding Failure

• Encoding failure: failure to process information into memory

LO 6.10 Why Do We Forget?

Forgetting• Forgetting as encoding failure

Externalevents

Sensorymemory

Short-term

memory

Long-term

memory

Attention

Encoding

Encodingfailure leadsto forgetting

Forgetting as Encoding Failure• Which penny is the real thing?

Forgetting as Retrieval Failure• Forgetting can result from failure to retrieve

information from long-term memory

Externalevents

AttentionEncoding

Retrieval failureleads to forgetting

RetrievalSensorymemory

Short-termmemory

Long-termmemory

Other Theories of Forgetting

• Decay Theory– Unless memories are periodically rehearsed, the

passage of time causes them to fade and eventually decay.

• Inteference Theory– Retroactive interference: forgetting due to interference

from newly learned information

– Proactive interference: forgetting due to interference from previously learned information

Forgetting as Storage Decay

12345 10 15 20 25 30

10

20

30

40

50

0

Time in days since learning list

Percentage oflist retainedwhen relearning

60

Retention,dropsthen levels off

Theories of Forgetting: Storage Decay

• Decay Theory– Unless memories are periodically rehearsed, the

passage of time causes them to fade and eventually decay.

Forgetting: Memory Trace Theory

• Memory trace: physical change in the brain that occurs when a memory is formed– decay: loss of memory due to the passage of

time, during which the memory trace is not used

– disuse: another name for decay, assuming that memories that are not used will eventually decay and disappear

t

Forgetting: Memory Trace Theory

• Memories after many years are not explained by memory trace theory.

Theory of Forgetting: Retrieval Failure

• Forgetting can result from failure to retrieve information from long-term memory

Externalevents

AttentionEncoding

Retrieval failureleads to forgetting

Retrieval

Sensorymemory

Short-termmemory

Long-termmemory

Theories of Forgetting: Storage Decay

• Decay Theory– Unless memories are periodically rehearsed, the

passage of time causes them to fade and eventually decay.

Forgetting as Storage Decay

123 45 10 15 20 25 30

10

20

30

40

50

0

Time in days since learning list

Percentage oflist retainedwhen relearning

60

Retention,drops

then levels off

Theory of Forgetting: Interference

• Inteference Theory

– Retroactive interference: forgetting due to interference from newly learned information

– Proactive interference: forgetting due to interference from previously learned information

Forgetting: Interference Theory

• Proactive interference: memory retrieval problem that occurs when older information prevents or interferes with the retrieval of newer information

LO Why Do We Forget?

Forgetting: InterferenceTheory

• Retroactive interference: memory retrieval problem that occurs when newer information prevents or interferes with the retrieval of older information

• Proactive interference: problems driving in England after learning in the U.S.

LO 6.10 Why Do We Forget?

Interference in Memory

Theory of Forgetting: Motivation

• Motivated forgetting: forgetting due to a desire to eliminate awareness of some unpleasant or disturbing memory

Two Types or Theories of Motivated Forgetting

Suppression occurs when a person consciously tries to forget something.

Repression occurs when a person unconsciously pushes unpleasant memories out of conscious awareness.

These memories continue to unconsciously influence the person’s thoughts, feelings,

and behavior.

Can people repress & later recover memories?

• Many memory researchers believe:

– It is naive to assume that people can accurately recover memories that were previously unconsciously repressed

– People can unknowingly manufacture false memories.

– False memories can be implanted into the minds of both children and adults.

Can people repress & later recover memories?

Many psychologists believe that memories “recovered” in therapy are actually false or pseudo memories.

Many research participants who are instructed to imagine that a fictitious event happened later develop a false memory of the fictitious event.

False childhood memories can be experimentally induced.

Can people repress & later recover memories?

Garry & Loftus implanted a false memory of being lost in a shopping mall at age 5 in 25% of their research participants (aged 18-53) after verification of the experience by a relative.

“Memories” from the first years of life are very suspect. Psychologists believe that the brain in insufficiently developed to create or sustain a long-term (until older childhood or adulthood) memory in a child under age three.

Repressed & Recovered Memories?

• Simply repeating imaginary events to people causes them to become more confident that they actually experienced these events.

• Certain techniques used in therapy to recover childhood memories of abuse (hypnosis and dream interpretation) can distort patients’ recollections of past events and create false memories of abuse.

Repressed Memories Controversy

• Current evidence supports the possibility of repressed memories and also the construction of false memories in response to suggestions of others.

• American Psychological Association, American Psychiatric Association,

• American Medical Association

The Brain Physiology of Memory

Long-Term Potentiation May Be the Neural Basis for Memory

• There is no scientific consensus on what an engram (or memory trace) is or where it is located in the brain.

• However, it appears that memories begin as electrical impulses traveling between neurons, and that the establishment of long-term memories involves changes in these neurons.

Long-Term Potentiation May Be the Neural Basis for Memory

• Long-term potentiation: the long-lasting strengthening of synaptic transmission along a specific neural circuit, which is believed to be the neural basis for long-term memory

– When a new memory is formed, changes occur in specific neurons, creating a kind of memory circuit.

– Each time the new memory is recalled, the neurons in this new circuit are activated, which strengthens their neural connections.

– As the communication links between the neurons increase in strength, the memory becomes established as a long-term memory.

How Does Storage Work? The Search for Memory

• Long-Term Potentiation– A long-lasting increase in the efficiency of

neural transmission at the synapses (junctions or connection points between nerve cells) .

– Donald O. Hebb argued that learning and memory must involve the enhancement of transmission at the synapses

How Does Storage Work? The Search for Memory

• Karl Lashley (1950)– trained rats to solve maze, then cut out

pieces of their cortex and retested their memory of maze

– partial memory retained– concluded memory is distributed

How Does Storage Work? The Search for Memory

• Long-Term Potentiation– increase in synapse’s firing potential after

brief, rapid stimulation– Kandel & Schwartz (1982) – classically

conditioned aplysia– Neural connections released more

neurotransmitter, became more sensitive/efficient

– Increased number of receptor sites

Long-term Potentiation

Double receptor sites

Event 1 Event 2

Classical Conditioning: Sea snail associates splash with a tail shock

Biological Factors Affecting Memory Processing

• Strong emotions make for stronger memories – stress hormones boost learning & retention; anxiety affects memory (cortisol)

• Drugs like alcohol that block neurotransmitters may prevent memory storage (retrograde amnesia)

• Blows to the head and electric current may also block information storage.

Brain Regions Involved in Memory Formation & Storage

– The hippocampus appears to be most important in the encoding of new explicit memories and the transfer of them from short-term to long-term memory.

Brain Regions Involved in Memory Formation & Storage

• The inability to form new memories due to the brain experiencing physical injury is called anterograde amnesia.

• This appears to be caused by damage to the hippocampus.

• Explicit memories cannot be formed, but implicit memories can.