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Memory

Our memories may fail us sometimes, but they are essential for life as we currently

experience it.

Without memory, we would be lost in the present.

In This Chapter

Three-Stage Model of Memory

Encoding Information into Memory

Retrieving Information from Memory

The Three-Stage Model of Memory

Sensory Memory

Short-Term Memory

Long-Term Memory

The Three-Stage Model of Memory

The Three-Stage Model

• The Three-Stage Model- Has guided research in memory since the late

1960s- Views memory as composed of three relatively

distinct stages

The Three-Stage Model

• Sensory memory (SM)- Consists of a set of five registers that serve as

temporary storage places, one from each sense- Used for incoming sensory information from the

physical environment until we attend to it, interpret it, and it proceeds to the next stage of memory

The Three-Stage Model

• Iconic memory- Is an exact copy of visual information - Less than a second in duration- Has very large capacity

Testing Iconic Memory

Temporal integration procedure

•Involves giving two random meaningless dot patterns sequentially at the same visual location with a brief time delay between the two presentations

•Creates a meaningful pattern when the two patterns are integrated somewhere in the memory system

•Time delay between the two presentations must be no longer than one second or no meaningful pattern can be perceived

An Example of the Temporal Integration Procedure

What do you see?

Testing Iconic Memory

Sperling’s full- and partial-report procedures

•Participants presented with a different 3 x 3 matrix of unrelated consonants (a total of 9) for 50 ms across numerous experimental trials

Full-report procedure

•Participants had to report the entire matrix•Participants sensed the entire matrix but could not report all 9 letters

Partial-report procedure

•Participants had to report only one row of the matrix•An immediate auditory cue resulted in successful recall; a one second delay resulted in poorer recall

A 3 3 3 Letter Matrix

• A 3 3 3 letter matrix like those used in Sperling’s iconic memory research

What does the lightning tell you?

The Three-Stage Model

• Short-term memory (STM)- Is the memory stage in which the recognized

information from sensory memory enters consciousness

- Involves present, conscious cognitive processing- Serves as a place to rehearse information - Involves concentrating on information or it will be

lost in 30 seconds

Capacity of Short-Term Memory

• Memory span- Average number of items that can be remembered across

a series of memory span trials- Humans have a memory span of 7+/- 2 (5 to 9) chunks of

information

• Memory span task- Tests for the capacity of short-term memory by giving a

series of items one at a time in a given order

• Chunk- Meaningful unit of information

Duration of Short-Term Memory

Distractor task

•People given a small amount of information (e.g., three unrelated consonants such as CWZ)•Immediate distraction used to deter concentration on the information for a brief time period (by counting backward aloud by 3’s)•Information recall gathered•Maintenance rehearsal used to keep information in short-term memory

Results for the Short-Term Memory Distractor Task

Short-Term Memory

• Maintenance rehearsal- Type of rehearsal in short-term memory in which

the information is repeated over and over again in order to maintain it

The Three-Stage Model

• Long-term memory (LTM)- Allows storage of information for a long period of

time (perhaps permanently)- Has essentially unlimited capacity

Types of Long-Term Memory

• Explicit memory (also called declarative memory)- Long-term memory for factual knowledge and

personal experiences- Requires conscious recall

• Two types of explicit memories- Semantic memories - Episodic memories

Types of Long-Term Memory

Types of Long-Term Memory

• Implicit memory (also called non-declarative memory)- Long-term memory that influences behavior, but does not

require conscious awareness or declarative statements

• Procedural memories- Have a physical procedural aspect to them

• Priming- Involves implicit influence of an earlier presented

stimulus on the response to a later stimulus

Amnesia: Loss of Long-Term Memories

• Amnesics- People with severe memory deficits following

brain surgery or injury

• Anterograde amnesia- Inability to form long-term memories for events

following brain surgery or trauma

• Retrograde amnesia- Inability to remember events before, especially

just before, surgery or trauma

The Mirror-Tracing Task

• The task is to trace the outline of a star (or some other shape) with a metal stylus when the star and your hand can be seen only in the mirror

• Thus, the tracing movements have to be made in the direction opposite from the way in which they appear in the mirror

Infantile Amnesia

• Cerebellum seems to be important for formation of implicit memories

• Hippocampus seems to be important for formation of explicit memories- Hippocampus does not fully develop until about

the age of 3- This explains why we cannot remember as adults

events that occurred prior to this age

Evidence for the Short-Term vs. Long-Term Distinction

Free recall task

•Experimental procedure in which participants are given a list of words one at a time, then asked to recall them in any order they wish•Primacy effect•Recency effect

After viewing the next slide, what can you conclude about each of these effects?

Evidence for the Short-Term vs. Long-Term Distinction

• Recency effect is caused by recall from short-term memory

• Primacy effect is the result of superior recall from long-term memory of the first few words in the list

Serial Position Effects for the Free Recall Task

Encoding Information into Memory

How We Encode Information

How to Improve Encoding

Memory System Processes

Encoding• Process of

transferring information from one memory stage to the next

Storage • Process of

maintaining information in a particular stage

Retrieval• Process of

bringing stored information from long-term memory to the conscious level in short-term memory

How We Encode Information

• Effortful processing - Occurs consciously and requires attention

• Automatic processing- Occurs subconsciously and does not require

attention

How We Encode Information

•Describes what types of encoding lead to better retrieval

•Contains three levels of processing•Physical: How the information appears•Acoustic: How the information sounds•Semantic: What the information means

Levels-of-Processing

Theory

Differences in Recognition Memory for Words Processed at Different Levels

• Participants were presented a long list of words one at a time and had to answer a question about each word as it was presented

• What does the figure tell us about differences in recognition memory?

How We Encode Information

• Elaborative rehearsal- Rehearsing information by relating new

information to information already in long-term memory

- Provides more retrieval cues to facilitate retrieval- Contrasts with maintenance rehearsal (i.e., the

repetitive cycling of information in short-term memory)

How We Encode Information

• Self-reference effect- Contends it is easier to remember information

that you have related to yourself- Suggests such connections provide more

retrieval cues and lend more meaning to the new information

Environmental Effects on Encoding

• Encoding specificity principle- Proposes that cues present during encoding

serve as the best cues for retrieval

• State-dependent memory- Depends upon the relationship of one’s

physiological state at the time of encoding and at the time of retrieval

Environmental Effects on Encoding

• Mood-dependent memory effects- Demonstrate that memory is better when a

person’s mood is the same during encoding and retrieval

• Mood-congruence effect- Demonstrates that memory is better for

experiences that are congruent with a person’s current mood

How to Improve Encoding

• Mnemonics- Memory aids that require elaborative rehearsal

• Method of loci- Sequential pieces of information to be remembered

are first associated with sequential locations in a very familiar room or location

• Peg-word system- Items to be remembered that are visually associated

in a memorized jingle

Other Tips for Improving Encoding

• Spacing effect (or distributed study effect)- Contends that memory will improve if you study

for an exam over an extended time interval rather than just a few days before the exam

• Overlearning- Involves studying material past the point of initial

learning- Has been demonstrated to aid in retrieval of that

information

Retrieving Information from Memory

How to Measure Retrieval

Why We Forget

The Reconstructive Nature of Retrieval

How to Measure Retrieval

• Recall- Measure of retrieval that requires the reproduction of

the information with essentially no retrieval cues

• Recognition- Measure of retrieval that only requires the identification

of the information in the presence of retrieval cues

• Relearning (savings method)- Measure of the amount of time saved when learning

information for a second time

An Early Study

• Ebbinghaus- Conducted first

experimental studies on human memory more than 100 years ago using the relearning method

- Mastered and relearned list of nonsense syllables

- Computed a savings score - Concluded that the

“forgetting curve” reveals that most forgetting occurs in the first two days after learning material

Hermann Ebbinghaus

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Forgetting Curve for Long-Term Memory

Why We Forget

• Contends sometimes forgetting is not really forgetting, but rather that the information never entered long-term memory in the first place

Encoding failure theory

• Suggests that forgetting occurs because of a problem in the storage of the information

Storage decay theory

An Example of Encoding Failure

Can you identify the real penny?Most Americans cannot. Why?

Why We Forget

• Posits that people forget because the cues necessary for retrieval are not available

• Suggests information is in memory, but inaccessible

Cue-dependent theory

• Proposes that other similar information interferes and makes the forgotten information inaccessible

Interference theory

Types of Interference

• Proactive interference- Occurs when information you already know makes

it hard to retrieve newly learned information

• Retroactive interference- Occurs when information you just learned makes it

hard to retrieve old information

Let’s consider an example of each kind of interference.

Types of Interference

The Reconstructive Nature of Retrieval

• Retrieval re-construction- Is guided by schemas

• Schemas- Are organized frameworks of knowledge about

people, objects, and events that tell us what normally happens in a given situation

- Allow more efficient information encoding and retrieving

- Can lead people to “misremember” information so that it is more consistent with personal schemas

The Reconstructive Nature of Retrieval

• Source misattribution- Occurs when we do not remember the true source of

a memory and attribute the memory to the wrong source

- Results in false memories, which are inaccurate memories that feel as real as accurate memories

• False memories- Can also occur because of the misinformation effect,

which occurs when a memory is distorted by subsequent exposure to misleading information

A Study of False Memories

Loftus and Palmer (1974) showed people a film of a traffic accident and later

tested their memory for the accident

•Some people were asked “How fast were the cars going when they smashed into each other?” •Others were asked “How fast were the cars going when they hit each other?”

Can you predict the responses for each group? What contributed to your answer?

Memory and Testimony

• False memories- Suggest that eyewitness testimony is subject to

error and manipulated by misleading information- Suggest that recovered memories are not

necessarily accurate