Memory is the ability to retain and retrieve information.
It encompasses the structures that account for this capacity.
Memory is fallible and deceptive because it is influenced by present events.
Why We Need Memory
To retain useful skills, knowledge, and expertise.
To recognize familiar people and places.
To build our capacity to use language.
To enjoy, share, and sustain culture.
To build a sense of self that endures: beliefs, values, memories, and understanding.
To go beyond conditioning by learning from experience, including lessons from one’s past and the experiences of others.
Without memory:
Everyone would be a stranger.
Every language would be foreign.
Every task would be new.
You yourself would be a stranger.
The Story of H.M. (Henry Gustav Molaison)
H.M. underwent experimental surgery that destroyed his ability to form long-term memories.
He could recall major historic events of his childhood, such as the stock market crash in 1929.
He could recall the gist of activities like roller skating that he loved as a boy.
After his death, H.M.’s brain was removed and frozen.
Researcher Jacopo Annese cut H.M.’s frozen brain into 2,401 slices, each 0.07 millimeters thick.
The slices were stained and mounted on slides.
The surgery involved removing most of his hippocampus and adjacent tissues in the medial temporal lobe from both hemispheres of his brain, along with the amygdala.
After surgery, H.M. was largely homebound and performed simple chores.
He retained a sense of humor and a positive outlook.
He enjoyed crossword puzzles and the TV sitcom "All in the Family."
Types of Memory
Declarative (explicit) memory: Conscious recollection of facts and events.
Procedural (implicit) memory: Learning demonstrated through performance (e.g., tracing a star or reading faster).
Biological Causes of Memory Loss
Traumatic Brain Injury (TBI)
Retrograde amnesia: Loss of memories of events before the accident; no trouble remembering things afterward (old memories lost).
Anterograde amnesia: Inability to form new memories for events after the accident (new memories lost).
Can result from surgical injury (as in H.M.'s case) or diseases like chronic alcoholism.
Memory as a Constructive Process
Memory is not like a digital recorder or video camera.
Memory is selective; we remember what we want to remember.
Recovering a memory is like watching flashes of a film and figuring out the rest of the scene.
We manufacture or "construct" our memories.
In reconstructing memories, people draw on many sources:
Family stories
Photographs
Home videos
Television
The Manufacture of Memory
Human memory is:
Highly selective
Often drawn from many sources
Reconstructive
We alter memories to make sense of the material, based on what we already know, which can lead to memory errors.
Sir Frederick Bartlett
Rejected the idea of long-term memory where material is stored unchanged until retrieval.
Saw memory as an active and often inaccurate process.
Conducted studies under natural conditions.
Said that past experiences help reconstruct the material that an individual is trying to remember.
Used the Native American fable "The War of the Ghosts."
Discovered that people found it difficult to recall the story exactly, even after repeated readings.
Parts of the story that failed to fit into the listener's understanding were omitted or transformed into more familiar forms.
The more time elapsed, the less reliable and accurate the recollections became.
Memory is largely a reconstructive process.
Source Misattribution
Source misattribution (source confusion): The inability to distinguish what you originally experienced from what you heard or were told later about an event.
Emotional Arousal and Memory
Emotional arousal can "sear" certain events into the brain.
Stress hormones signal the brain that something important has happened.
Events that triggered the arousal make an indelible impression.
Clear memories may repeatedly occur spontaneously, as if they were "burned" in the mind.
It is adaptive for strong emotional experiences to create strong, more reliable memories (James McGaugh).
Emotions, Stress Hormones, the Amygdala, and Memory
Intense emotion causes the brain to form intense memories.
Emotions can trigger a rise in stress hormones.
These hormones trigger activity in the amygdala.
The amygdala increases memory-forming activity and engages the frontal lobes and basal ganglia to "tag" the memories as important.
Memories are stored with more sensory and emotional details.
Details can trigger rapid, unintended recall of the memory.
Relates to PTSD: Traumatized people can have intrusive recall that feels like re-experiencing the event.
Memories may feel vivid but are not necessarily accurate; they get altered every time we recall them.
Trauma therapy depends on this "reconsolidation."
Flashbulb Memories
Unusual, shocking, or tragic events hold a special place in memory.
Called flashbulb memories because of their surprise, illumination, and photographic detail.
These memories may feel vivid but are not necessarily accurate; they get altered every time we recall them.
Trauma therapy depends on this "reconsolidation."
Six ‘Canonical’ Categories of Flashbulb Memories
Location: Remembering where you heard the news.
Ongoing event: Remembering what you were doing at the time you heard the news.
Informant: Remembering who told you about the event.
Emotional affect in others: Noticing the emotional reactions of others.
Emotional affect in self: Noticing the emotional reactions of oneself.
Aftermath/consequentiality: Remembering what you did after you heard the news.
Characteristics of Flashbulb Memories
Detailed and vivid memory stored and retained for a lifetime.
Associated with important historical or autobiographical events.
More detailed than ordinary memories, including characteristics like:
Where were you?
What were you doing?
Who was with you?
How did you feel?
How did those around you feel?
What happened next?
Require the participation of the amygdala and possibly other parts of the brain that regulate mood and alertness.
The Conditions of Confabulation
Confabulation: Confusion of an event that happened to someone else with one that happened to you, or a belief that you remember something when it never actually happened.
Confabulation Examples
Memory: "I went surfing at sunrise when we took a family trip to California."
Actual event: "I watched other people surf at sunrise when we took a family trip to California."
Having strong feelings about a memory does not mean that the memory is accurate.
Likelihood of Confabulation
The image of the event contains many details that make it feel real.
The event is easy to imagine.
You have thought, heard, or told others about the event many times (imagination inflation).
Time-Gap Experience
Engaging in a fairly complicated task (such as driving a car) and upon completion of the task, you realize that you have no conscious recollection of the task you just completed.
To demonstrate the duration of visual or iconic memory, swing a flashlight in a dark room.
Because the image lingers for a fraction of a second after the flashlight is moved, you see the light as a continuous stream, rather than as a succession of individual points.
Echoic Memory
A weaker “echo” (echoic memory) of auditory information can last up to 4 seconds.
The Eyewitness On Trial
Eyewitnesses are not always reliable.
Factors influencing accuracy:
Differing ethnicity
Leading Questions
Misleading information
The reconstructive nature of memory makes it vulnerable to suggestion.
Memories are also influenced by the way in which questions are put to the eyewitness and by suggestive comments made during an interrogation or interview.
Constructed Memories
It is more common that there is mistaken testimony than intentional lying.
People are overconfident about their fallible memories, not realizing that their memories are constructions.
We tend to alter our memories to fit our current views.
Schema Influence
Using schemas is a useful mental shortcut but can lead us to make mistakes in memory if we use them too much.