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Memory

Copyright © Allyn & Bacon 2006

What is Memory?

• The ability to recall past events, images, ideas, or previously learned information or skills

• The storage system that allows a person to retain and retrieve previously learned information


How Does the Memory Process Begin?

The brain as Information Processor

Long-Term

Memory

Three Processes

Short-Term

Memory

2. Storage 3. Retrieval1. Encoding

Information

Sensory Memory


Encoding

• Organizing sensory information so it can be processed by the nervous system• Visual• Auditory• Olfactory


Encoding

1. Attention is important

– Divided attention interferes with encoding

2. Levels of Processing

– Brain encodes information in different ways or on different levels

– Deeper processing leads to deeper memory


Levels of Processing

• All approaches emphasize:

– Importance of encoding

– How information is encoded

– That encoding is flexible

– Effects of cues

– Effects of preconceived biases


Neuroscience and Encoding• PET and MRI used to study neurobiological bases

of memory

• Two important areas:

a. Prefrontal cortex

• Left: Encoding new memories

• Right: Retrieving old memories


Neuroscience and Encoding

Two important areas:a. Prefrontal cortex

b. Temporal Lobes

• temporal lobes active during encoding of associations


Storage is:– The process of maintaining or keeping

information readily available– The locations where information is held

• Memory stores

Types of Memory Storage


A. Sensory Memory


– Performs initial encoding– Provides brief storage– Two types

– Iconic Memory– Echoic Memory

– Information must be transferred to short-term storage or it will be forgotten



B. Short-Term Storage– Holds information for processing

– Fragile

– Other terms:• Short term Memory (emphasizes

duration)

• Working Memory (emphasizes active nature)


Short-Term Storage

1. Early Research on Short-Term Memorya. Duration

Information in short-term memory is available for 20–30 seconds at most.


Early Research on Short-Term Memory

b. Quantity of information stored• Memory Span

• 5–7 items (George Miller, 1956)• But what is an item?


What is an item?

1 4 9 1 6 2 5 3 6 4 9 6 4 8 1 1 0 0

1 4 9 16 25 36 49 64 81 100

Cat orange escalator watch bench

The orange cat sat on the bench watching the escalator.

• Such groupings are called chunks


Early Research on Short-Term Memory

c. Rehearsal• Process of repeatedly verbalizing or

thinking about information to keep it active in memory

• Two types:

• Maintenance rehearsal

• Elaborative rehearsal


Short-Term Storage

2. The Emergence of Working Memory– Temporarily holds current or recent

information for immediate or short-term use

– Does not simply store information

– Information is maintained for 20–30 seconds while active processing (e.g., rehearsal) takes place


C. Long-Term Memory


– Relatively permanent record of memory

– Stored indefinitely

– Capacity seems unlimited

– Several different types


Long Term Memory

1. Types:

a. Types based on contenti. Procedural memory

ii. Declarative memory

a) Episodic memory

b) Semantic memory

b. Types based on awarenessi. Explicit memory

ii. Implicit memory


Long Term Memory

2. Practice and Storage• Two types:

• Massed practice

• Distributed practice

• Found distributed practice best

• Especially for perceptual-motor skills


Neuroscience and Storage• Consolidation

• Process of changing a temporary memory to a permanent memory


• The process by which stored information is recovered from memory– Depends on

• How retention is measured

• How information is encoded and stored

Retrieval


Retention: Measures of Retrieval

Two types of retrieval task:1. Recall

• Free recall• Serial recall• Paired associate

2. Recognition

3. Relearning


RetrievalRetrieval Success and Failure:

• Sometimes information is in memory, but is inaccessible

• Why?• One reason: poor retrieval cues


What Facilitates Retrieval?

Retrieval

1. Primacy and Recency Effects

a. Primacy Effect• Better memory for items at the

beginning of a list• Better attention• More time for rehearsal


b. Recency Effect

Primacy and Recency Effects

– Better memory for items at the end of a list– Items still in short-term storage


• Exception:

Primacy and Recency Effects

• Restorff effect• Occurs when recall is better for a

distinctive item, even if it occurs in the middle of a list


2. Imagery

What Facilitates Retrieval

• The creation of a mental picture of a sensory or perceptual experience

• Important memory aid• Preserves perceptual information that might

otherwise decay


Flashbulb Memories

Retrieval

• Vivid

• Remembered with confidence

• Detailed memory for events surrounding a dramatic event


– One theory says this is a special type of memory for events that are highly emotional• Makes them especially accurate

• Other psychologists disagree– Not a special mechanism– The emotional component makes these

memories• More distinctive (affecting encoding)

• More often rehearsed (enhancing retrieval)

Flashbulb Memories


• Research shows that flashbulb memories

– Are vivid

– Are far from accurate

– Can change over time

Flashbulb Memories


Early Studies

– Found that college students made changes in stories when recalling them• Leveling• Sharpening• Assimilation


Early Studies• Contemporary explanations center on the

reconstructive nature of memory– Memory formation often relies on a

schema– We can not remember all the details of

an event• Schemas help fill in the missing details


ForgettingKey Causes of Forgetting

1. Decay of Information• The loss of information from memory

due to disuse and the passage of time

• Disintegration of a physiological memory trace

2. Interference in Memory• The suppression of one bit of

information by another


Interference in Memory

• Two types of interferencea. Proactive interference

• Previously learned information interferes with the ability to learn new information

b. Retroactive interference• Newly learned information interferes with

the ability to recall previously learned information


Key Causes of Forgetting

3. Interference with Attention– Likely causes of absentmindedness

• Encoding failure

– Divided attention• Problem for both encoding and

retrieval• More of a problem during encoding


Interference with Attention• Stroop Effect

YELLOWREDBLUEBLACKGREENREDBLUE

YELLOWREDBLUEBLACKGREENREDBLUE

– Read the INK COLOR of the words below as quickly as you can


ForgettingSpecial Types of Forgetting

1. Eyewitness Testimony• Both jurors and judges place high

confidence in eyewitnesses– However, research shows

eyewitnesses are often inaccurate– Loftus’ (1975, 1979) research

» Demonstrated memory distortion may be caused by the wording of a question


Eyewitness Testimony• Demonstrates the misinformation effect• High motivation to remember an event can

actually distort it

• Accuracy and confidence are uncorrelated

– Speed of identification is a better indicator of accuracy than confidence


Special Types of Forgetting

2. Motivated Forgetting– Occurs when frightening, traumatic events

are forgotten because people want to forget them

– First suggested by Freud (1933) • Believed such memory loss occurred

through repression– Underlies the debate on recovered

memory

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