Psychology: Memory
8.1 How Memory Functions
How Memory Functions
Memory is an information-processing system that encodes, stores, and retrieves information over time.
- Encoding: input of information into the memory system.
- Storage: retention of the encoded information.
- Retrieval: act of getting information out of storage and into conscious awareness.
Types of memory encoding
| visual encoding | acoustic encoding | semantic encoding | |
|---|---|---|---|
| description | encoding of images | encoding of sounds and words | encoding of words and their meaning |
| example | recalling car, dog, book more easily than level, truth, value | learning the alphabet through song | recalling the meaning of psychology |
| effectiveness | shallow processing | shallow processing | deep processing (best for verbal information) |
Memory storage follows a staged process:
- Sensory memory: brief storage (up to a few seconds) of sensory events like sights and sounds. Most information is discarded unless attended to.
- Short-term memory (STM): temporary storage (15–30 seconds) that processes incoming sensory memory. Capacity is limited to about 7 ± 2 items (Miller, 1956) or 4 ± 1 in contemporary research (Cowan, 2010).
- Long-term memory (LTM): continuous storage with a theoretically unlimited capacity. Information here is organized in semantic networks, where related concepts are linked and activation spreads to associated ideas.
Two models describe memory storage:
- Atkinson-Shiffrin model: Information passes sequentially from sensory memory → short-term memory → long-term memory via rehearsal.
- Baddeley and Hitch model: Short-term memory is divided into specialized systems (visuospatial sketchpad, phonological loop, episodic buffer) coordinated by a central executive.
Memory retrieval occurs through three methods:
- Recall: retrieving information without cues (e.g., essay tests).
- Recognition: identifying previously learned information when encountered again (e.g., multiple-choice tests).
- Relearning: reacquiring knowledge that was once learned (e.g., relearning Spanish after years of disuse).
Long-term memory is divided into two types:
-
Explicit (declarative) memory: consciously recalled information, including:
- Episodic memory: personal experiences (e.g., your last birthday).
- Semantic memory: facts and concepts (e.g., the capital of the United States).
-
Implicit memory: unconscious retention influencing behavior, including:
- Procedural memory: skills and actions (e.g., riding a bicycle).
- Priming: exposure to a stimulus affecting later responses.
- Emotional conditioning: classically conditioned emotional responses.
8.2 Parts of the Brain Involved with Memory
Brain systems involved in memory
Memory is not stored in a single brain region but relies on multiple, interacting systems. Research shows that the hippocampus encodes new memories, the amygdala prioritizes emotionally charged memories, the cerebellum supports procedural skills, and the prefrontal cortex contributes to semantic and episodic recall.
Role of key brain areas in memory
| hippocampus | amygdala | cerebellum | prefrontal cortex | |
|---|---|---|---|---|
| primary memory function | encodes new memories | prioritizes emotionally charged memories | stores procedural skills | supports semantic and episodic recall |
| memory type | declarative & episodic | emotional memories | procedural memories | semantic tasks |
| example task | recalling a conversation | freezing at a tone paired with shock | playing a piano piece | categorizing a noun as living or non-living |
Emotion strengthens memory consolidation. The amygdala releases neurotransmitters and hormones during emotionally arousing events, enhancing long-term storage. This explains flashbulb memories—exceptionally vivid recollections of significant events, such as where one was during the 9/11 attacks.
Dig Deeper: Inaccurate and False Memories
Memory is reconstructive: when we recall an event, its components (time, visuals, smells) are pulled from different stores and reassembled. Each step in this process can introduce errors, leading to false memory—remembering something that never happened. Studies show people can recall hearing words they were never exposed to (Roediger & McDermott, 2000).
Memory construction creates new memories, while reconstruction retrieves old ones—but retrieval alters them. A memory in short-term storage is malleable: new events can be added, and past details can be changed unintentionally during recall (Roediger & DeSoto, 2015).
External misinformation can distort memories through suggestibility, a process where false details from outside sources are incorporated into recollections. This contributes to inaccuracies even in vivid, so-called flashbulb memories.
8.3 Problems with Memory
Problems with Memory
Forgetting and memory errors arise from four main sources:
- Amnesia: loss of long-term memory caused by disease, physical trauma, or psychological trauma.
- Encoding failure: information is never stored in long-term memory because it was not attended to or processed.
- Interference: new or old information blocks recall of target memories (proactive vs. retroactive).
- Distortion errors: memory is altered by suggestion, misattribution, or bias.
Types of amnesia
| retrograde amnesia | anterograde amnesia | |
|---|---|---|
| Direction of memory loss | Loss of memories from before the trauma | Inability to form new memories after the trauma |
| Example | Forgets spouse, children, and past life after head injury | Cannot remember new people met after brain damage |
Schacter’s seven sins of memory
| Sin | Type | Description | Example |
|---|---|---|---|
| Transience | Forgetting | Unused memories fade over time | Forget events from long ago |
| Absentmindedness | Forgetting | Lapses in attention prevent encoding | Forget where your phone is |
| Blocking | Forgetting | Temporary inability to retrieve stored information | Tip-of-the-tongue phenomenon |
| Misattribution | Distortion | Confusing the source of a memory | Recalling a dream as a waking memory |
| Suggestibility | Distortion | False memories from external suggestions | Witness misidentification after leading questions |
| Bias | Distortion | Current beliefs distort past memories | Remembering past events to fit present views |
| Persistence | Intrusion | Involuntary recall of unwanted memories | Reliving a traumatic car accident |
Interference occurs when competing information blocks recall. Proactive interference happens when old information hinders new learning (e.g., using an old phone number after changing it). Retroactive interference occurs when new information hinders recall of old information (e.g., studying Erikson’s theory and forgetting Ebbinghaus’s forgetting curve).
8.4 Ways to Enhance Memory
Ways to Enhance Memory
Memory improves when information is encoded more deeply, organized into manageable units, and linked to existing knowledge. Strategies that support these processes include:
- Rehearsal: Conscious repetition of information to strengthen its retention in memory.
- Chunking: Organizing information into smaller, meaningful groups (e.g., breaking a phone number into area code and local digits).
- Elaborative rehearsal: Linking new information to prior knowledge to make it more meaningful and memorable.
Additional techniques to enhance memory include:
- Mnemonic devices: Memory aids that organize information for encoding, such as acronyms, acrostics, or rhyming jingles. Example: "HOMES" for the Great Lakes (Huron, Ontario, Michigan, Erie, Superior).
- Expressive writing: Writing about traumatic experiences can boost short-term memory capacity over time.
- Verbalization: Saying information aloud (or mouthing words) increases its distinctiveness and improves recall.
Memory is also strengthened by lifestyle practices:
- Exercise: Regular aerobic activity promotes neurogenesis in the hippocampus, a brain region critical for memory.
- Sleep: Sleep supports memory consolidation, organizing and storing information into long-term memory.
- Distributed practice: Spreading study sessions over time, rather than cramming, improves retention and reduces interference.
- Minimizing interference: Study in quiet environments to avoid distractions that hinder recall.
Comparison of memory-enhancing strategies by mechanism and typical use
| Rehearsal | Chunking | Elaborative rehearsal | Mnemonic devices | Verbalization | Exercise | Sleep | Distributed practice | |
|---|---|---|---|---|---|---|---|---|
| Mechanism | Repetition | Grouping into units | Linking to prior knowledge | Memory aids (e.g., acronyms) | Increasing distinctiveness | Promoting neurogenesis | Consolidating memories | Spreading study over time |
| Best for | Memorizing facts or lists | Remembering sequences (e.g., phone numbers) | Understanding and retaining complex concepts | Recalling ordered information (e.g., steps, stages) | Improving recall of individual items | Enhancing long-term memory capacity | Stabilizing new memories | Avoiding cramming effects |
Glossary
- memory
- Memory is the set of processes used to encode, store, and retrieve information over different periods of time.
- encoding
- Encoding is the input of information into the memory system.
- automatic processing
- Automatic processing is the encoding of details like time, space, frequency, and the meaning of words, usually without conscious awareness.
- effortful processing
- Effortful processing is encoding that requires work and attention.
- semantic encoding
- Semantic encoding is the encoding of words and their meaning.
- visual encoding
- Visual encoding is the encoding of images, and acoustic encoding is the encoding of sounds, especially words.
- self-reference effect
- Semantic encoding produces better memory for verbal information than visual or acoustic encoding, especially through the self-reference effect.
- storage
- Storage is the creation of a permanent record of information.
- Atkinson-Shiffrin model
- The Atkinson-Shiffrin model says memory moves through sensory memory, short-term memory, and long-term memory.
- sensory memory
- Sensory memory stores brief sensory events such as sights, sounds, and tastes for only a couple of seconds, and unattended sensory input is discarded.
- short-term memory (STM)
- Short-term memory is a temporary storage system that processes incoming sensory memory and lasts about 15 to 30 seconds.
- rehearsal
- Rehearsal moves information from short-term memory to long-term memory; active rehearsal repeats information, and elaborative rehearsal links new information to what you already know.
- levels of processing
- The levels of processing hypothesis says that the deeper you think about something, the better you remember it.
- proactive interference
- Short-term memory retention is affected by decay and interference; proactive interference means previously learned information hinders new learning.
- long-term memory (LTM)
- Long-term memory is continuous storage of information and is believed to have essentially unlimited capacity.
- semantic networks
- Long-term memory is organized in semantic networks, where related concepts are linked and activating one concept spreads activation to connected concepts.
- spreading activation
- Spreading activation is the process by which activating part of a semantic network also activates linked concepts to a lesser degree.
- explicit memory
- Explicit memory is memory we consciously try to remember, recall, and report; it is also called declarative memory.
- episodic memory
- Episodic memory is memory about personally experienced events, especially the what, where, and when of an event; it is also called autobiographical memory.
- semantic memory
- Semantic memory is knowledge about words, concepts, and facts, usually reported as facts.
- implicit memory
- Implicit memory consists of long-term memories that are not in consciousness and are shown through performance rather than conscious recall.
- procedural memory
- Procedural memory is implicit memory for skilled actions and how to do things, such as brushing your teeth, riding a bicycle, or driving a car.
- priming
- Priming is implicit memory in which exposure to one stimulus affects the response to a later stimulus.
- retrieval
- Retrieval is the act of getting information out of long-term memory storage and back into conscious awareness.
- recall
- Recall is retrieval without cues, recognition is identifying previously learned information after encountering it again, and relearning is learning information that was previously learned.
- engram
- The engram is the physical trace or physical representation of memory, and Lashley’s equipotentiality hypothesis says that if part of one memory area is damaged, another part of the same area can take over.
- amygdala
- The amygdala regulates emotion, helps store emotionally arousing memories, and contributes to memory consolidation and deeper encoding of emotional events.
- hippocampus
- The hippocampus is involved in recognition and spatial memory, projects information to cortical regions that give memories meaning, and helps with memory consolidation.
- anterograde amnesia
- Damage to the hippocampus can prevent formation of new declarative memories while leaving older memories intact; this is seen in anterograde amnesia.
- cerebellum
- The cerebellum helps create implicit memories, especially procedural memory, motor learning, and classical conditioning.
- prefrontal cortex
- The prefrontal cortex is involved in semantic processing and retrieval, with left frontal activity linked to encoding and right frontal activity linked to retrieval.
- arousal theory
- Arousal theory says strong emotions trigger strong memories and weaker emotional experiences form weaker memories.
- flashbulb memory
- A flashbulb memory is an exceptionally clear recollection of an important event, often with strong emotional associations.
- reconstruction
- Memory reconstruction means that remembering puts stored components back together, so memories can be altered and inaccurate.
- amnesia
- Amnesia is the loss of long-term memory caused by disease, physical trauma, or psychological trauma.
- retrograde amnesia
- Retrograde amnesia is loss of memory for events that occurred before the trauma.
- suggestibility
- Suggestibility is the effect of misinformation from external sources that creates false memories.
- misinformation effect paradigm
- The misinformation effect means that after exposure to additional and possibly inaccurate information, a person may misremember the original event.
- false memory syndrome
- False memory syndrome is the recall of false autobiographical memories.
- bias
- Memory can be distorted by bias, including stereotypical bias, egocentric bias, and hindsight bias.
- persistence
- Persistence is the involuntary recall of unwanted memories, especially unpleasant ones, that interferes with concentration.
- forgetting
- Forgetting is the loss of information from long-term memory.
- encoding failure
- Encoding failure occurs when information is never stored in memory in the first place, often because attention and effortful encoding were insufficient.
- transience
- Transience is the fading of memories over time due to storage decay.
- absentmindedness
- Absentmindedness is memory failure caused by lapses in attention or focus elsewhere.
- blocking
- Blocking is the tip-of-the-tongue phenomenon, in which stored information cannot be accessed.
- misattribution
- Misattribution is confusing the source of information and creating a false memory on your own.
- retroactive interference
- Proactive interference happens when old information hinders recall of newly learned information, and retroactive interference happens when new information hinders recall of older information.
- memory-enhancing strategy
- Memory-enhancing strategies include rehearsal, chunking, elaborative rehearsal, mnemonic devices, expressive writing, saying words aloud, avoiding interference, exercise, and sleep.
- chunking
- Chunking organizes information into manageable bits or chunks.
- mnemonic device
- Mnemonic devices are memory aids that help organize information for encoding.
- elaborative rehearsal
- Elaborative rehearsal means thinking about the meaning of new information and linking it to knowledge already stored in memory.
- self-reference effect
- The self-reference effect helps memory by making material personally meaningful.