Retrieving information from long-term memory is essential for daily functioning.
There are three primary methods of retrieving information:
Recall:
Accessing information without cues.
Example: Essay tests.
Recognition:
Identifying previously learned information when encountered again.
Involves comparison.
Example: Multiple-choice tests, recognizing classmates at a reunion.
Relearning:
Learning information that was previously learned.
Example: Picking up a language quickly after not speaking it for years.
Brain Functions Involved in Memory
Karl Lashley's Research:
Explored where memories are stored in the brain through lesions in animal brains.
Searched for the engram: the physical representation of memory.
Equipotentiality Hypothesis:
If one part of the brain area involved in memory is damaged, another part can take over the memory function.
Modern psychologists are making progress in locating the engram.
Brain Areas Involved:
Amygdala
Hippocampus
Cerebellum
Prefrontal Cortex
The Amygdala
Function:
Regulates emotions such as fear and aggression.
Plays a role in memory storage influenced by stress hormones.
Experiment:
Rats conditioned with a tone paired with a foot shock to create fear memory.
Cell death induced in the lateral amygdala resulted in fear memory fading.
Memory Consolidation:
The amygdala facilitates encoding memories at a deeper level when the event is emotionally arousing.
The Hippocampus
Experiments:
Rats with lesions in the hippocampi showed memory impairment in object recognition and maze running.
Involved in normal recognition memory and spatial memory.
Functions:
Projects information to cortical regions to give memories meaning and connect them with other memories.
Plays a part in memory consolidation.
Injury to this area can result in the inability to process new declarative memories.
Case study: Patient H.M.
Had both temporal lobes (hippocampi) removed to control seizures.
Resulted in significant declarative memory impairment; he could not form new semantic knowledge but could still remember information before the surgery.
The Cerebellum and Prefrontal Cortex
Cerebellum:
Important for implicit memories (procedural memory, motor learning, and classical conditioning).
Example: Rabbits with damaged cerebellums could not learn the conditioned eye-blink response.
Prefrontal Cortex:
Involved in processing and retaining information.
Perceptual vs. Semantic Tasks:
Semantic tasks (categorizing nouns) resulted in better recall and more activation in the left inferior prefrontal cortex.
Encoding associated with left frontal activity, while retrieval is associated with the right frontal region.
Neurotransmitters
Specific neurotransmitters involved with memory:
Epinephrine
Dopamine
Serotonin
Glutamate
Acetylcholine
Communication among neurons via neurotransmitters is critical for developing new memories.
Repeated activity leads to increased neurotransmitters and more efficient synaptic connections, aiding memory consolidation.
Arousal Theory:
Strong emotions trigger the formation of strong memories; weaker emotional experiences form weaker memories.
Stress can cause the brain to secrete more glutamate, aiding memory of stressful events.
Flashbulb Memory
Definition:
An exceptionally clear recollection of an important event.
Example: Remembering where one was during the 9/11 terrorist attacks.
Can be related to both positive and negative events.
Inaccurate and False Memories
Flashbulb memories can have decreased accuracy over time.
Memory is not like a video recording.
Memory Reconstruction:
Components of a memory (time, visual elements, smells) are stored in different places and must be pieced back together during recall, creating opportunities for error.
False Memory:
Remembering something that did not happen.
Problems with Memory
Amnesia:
Loss of long-term memory due to disease, physical trauma, or psychological trauma.
Case study: K.C., who suffered severe amnesia after a motorcycle accident, could not remember any events from his life.
Types of Amnesia:
Anterograde Amnesia:
Inability to remember new information after trauma, but can remember information prior to the injury.
Hippocampus is usually affected.
Inability to transfer information from short-term to long-term memory (inability to consolidate memories).
Can form new procedural memories but not episodic or semantic memories.
Example: Patient H.M. could not remember reading the same magazine repeatedly but improved at solving the same puzzle each day.
Retrograde Amnesia:
Loss of memory for events that occurred prior to the trauma.
Difficulty remembering episodic memories.
Example: Former NFL player Scott Bolzan lost 46 years of his life due to a head injury.
Memory Construction and Reconstruction
Construction: Formulation of new memories.
Reconstruction: Process of bringing up old memories.
Memories can be altered and modified during retrieval; new events can be added, and past events can be changed, leading to inaccuracies and distortions.
Suggestibility
Suggestibility:
Effects of misinformation from external sources that leads to the creation of false memories.
Example: Eyewitnesses focusing on white vans during the D.C. sniper attacks after the police chief mentioned it on television, even though the suspects were driving a blue sedan.
Eyewitness Misidentification
Memory and reconstruction of events can be fragile.