MEMORYPertemuan 10

Matakuliah : L0014 / Psikologi UmumTahun : 2007

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MEMORY

THREE STAGES OF MEMORYFORGETING AND WHY IT OCCURSBIOLOGICAL BASIS OF MEMORY

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DEFINITION

• memory is an organism's ability to store, retain, and subsequently retrieve information

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PROCESS

• Encoding or registration (processing and combining of received information)

• Storage (creation of a permanent record of the encoded information) – Stages theory of memory : a model of memory based on the

idea that we store information in three separate but linked memory

• Sensory Register• Short Term Memory• Long Term Memory

• Retrieval or recall (calling back the stored information in response to some cue for use in a process or activity)

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Stage model of memory

Sensory input Sensory register Short Term Memory Long Term Memory

Forgetting

Forgetting

Rehearsal

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STAGES THEORY OF MEMORYSensory Register (1)

• The first stages of memory, in which an exact image of each sensory experience is held briefly until it can be processed

• The ability to look at an item, and remember what it looked like with just a second of observation, or memorization

• Characteristics :– corresponds approximately to the initial 200 - 500 milliseconds

after an item is perceived – A complete replica of the sensory experiences :

• For visual information : lasting about 1/4 of a second• For auditory information : a vivid image of what we hear is retain about

1/4 of a second, but a weaker echo is retained for up to 4 seconds

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• Research by George Sperling (1960) "partial report paradigm”

• Subjects were presented with a grid of 12 letters, arranged into three rows of 4. After a brief presentation (1/20 seconds), subjects were then played either a high, medium or low tone, cuing them which of the rows to report.

• Sperling was able to show that the capacity of sensory memory was approximately 12 items, but that it degraded very quickly (within a few hundred milliseconds). Because this form of memory degrades so quickly, participants would see the display, but be unable to report all of the items (12 in the "whole report" procedure) before they decayed.

• This type of memory cannot be prolonged via rehearsal.

STAGES THEORY OF MEMORYSensory Register (2)

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STAGES OF MEMORYShort Term Memory – STM (1)

• The 2nd stage of memory, in which five to nine bits of information can be stored for brief periods of time

• Short-term memory allows one to recall something from several seconds to as long as a minute without rehearsal, Its capacity is also very limited

• George A. Miller, when working at Bell Laboratories, conducted experiments showing that the store of short term memory was 7 2 items (the title of his famous paper, "The magic number 72").

• Modern estimates of the capacity of short-term memory are lower, typically on the order of 4-5 items

Two important examples of STM control processes :• Rehearsal• Chunking

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STAGES OF MEMORYSTM – REHEARSAL (2)

• Rehearsal is mental repetition of information to retain it longer in STM

• Research by Lloyd and Margaret Peterson (1959)single combination of three consonants counting backwards (intervals 0 – 18 seconds)

LRP 10 9 8 7 6 5 4 3 2 1 recall LRP

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STAGES OF MEMORYSTM – CHUNKING (3)

• The memory capacity can be increased through a process called chunking. For example, if presented with the string:

FBIPHDTWAIBM

People are able to remember only a few items. • However, if the same information is presented in the following way:

FBI PHD TWA IBM • people can remember a great deal more letters. This is because

they are able to chunk the information into meaningful groups of letters.

• Beyond finding meaning in the acronyms above, Herbert Simon showed that the ideal size for chunking letters and numbers, meaningful or not, was three.

• This may be reflected in the tendency to remember phone numbers as several chunks of three numbers with the final four-number groups generally broken down into two groups of two.

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LONG TERM MEMORY - LTM (1)

• The 3rd stage of memory, involving the storage of information that is kept for long periods of time

• can store much larger quantities of information for potentially unlimited duration (sometimes a whole life span).

• LTM vs. STM1. The way which information is recalled – using cues2. The form in which information is stored in memory –

meaning or semantic codes3. The reasons that forgetting occurs4. The physical location of these functions in the brain

– STM : frontal lobes, cerebral cortex– LTM : integrated in Hippocampus, then transferred to the

areas of the cerebral cortex involved in language and perception for permanent storage

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LONG TERM MEMORY – LTM (2)TYPES

• Declarative Memory requires conscious recall, in that some conscious process must call back the information. It is sometimes called explicit memory, since it consists of information that is explicitly stored and retrieved.

Declarative Memory

Semantic Memory Episodic Memory

Procedural Memory

• Procedural Memory is not based on the conscious recall of information, but on implicit learning. Procedural memory is primarily employed in learning motor skills and should be considered a subset of implicit memory. It is revealed when we do better in a given task due only to repetition - no new explicit memories have been formed, but we are unconsciously accessing aspects of those previous experiences. Procedural memory involved in motor learning depends on the cerebellum and basal ganglia.

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• Declarative memory can be further sub-divided into – semantic memory, which concerns facts taken independent of

context– episodic memory, which concerns information specific to a

particular context, such as a time and place.

• Semantic memory allows the encoding of abstract knowledge about the world, such as "Paris is the capital of France".

• Episodic memory, is used for more personal memories, such as the sensations, emotions, and personal associations of a particular place or time. Ex. Autobiographical memory

LONG TERM MEMORY – LTM (3)TYPES : DECLARATIVE MEMORY

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LONG TERM MEMORY – LTM (4)ORGANIZATION

• Make a story• Associative network : memories are associated,

linked together, through experience

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RETRIEVAL• Recall

– A measure of memory based on the ability to retrieve information from long – term memory with few cues

– Serial position effect : the finding that immediate recall of items listed in a fixed order is often better for items at the beginning and end of the list that those in the middle

– The tip of the tongue phenomenon

• Recognition– A measure of memory based on the ability to select

correct information from among the options provided

• Relearning/savings– A measure of memory based on the length of time it

takes to relearn forgotten material

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RETRIEVAL (2)

• Serial learning– Serial position effect : The finding that immediate recall of

items listed in a fix order is often better for items at the beginning and end of the list than for those in the middle

– The first item – rehearsed enough time to transfer to LTM– The last/end item – still in STM

• The Tip of the Tongue phenomenon– Trying to recall a fact that we can almost remember – by

cues

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An alternative to stage model

• Elaboration– The process of creating associations between a new

memory and existing memories

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FORGETTING (1)

• Decay Theory– The theory that forgetting occurs as the memory trace fades

over time– Happen in Sensory Register and STM

• Interference Theory– The theory that forgetting occurs because similar memories

interfere with the storage or retrieval of information• Proactive interference : interference created by memories from

prior learning• Retroactive interference : interference created by memories from

later learning

– Happen in LTM – semantic memory and STM

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FORGETTING (2)

• Reconstruction (schema) Theory– The theory that information stored in the LTM

sometimes changes over time to become more consistent with our beliefs, knowledge and expectation (schema)

– False memory : remembering an event that did not occur or that occurred in a way that was substantially different from the memory of the event

• Theory of Motivated forgetting– Forgetting that is believed to be based on the upsetting

or threatening nature of the information that is forgotten

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MEMORY DISORDERS• Amnesia : Loss of memory

– Retrograde amnesia : • a memory disorder characterized by an inability to retrieve old LTM, generally for a

specific period of time extending back from the beginning of the disorder• Caused by seizures, brain damage of various sorts, a blow to the head, highly

stressful events

– Anterograde amnesia• Disorder in memory characterized by an inability to store and/or retrieve new

information in LTM• Not affect the LTM – procedural memory

• Korsakoff’s syndrome– A disorder involving both anterograde and retrograde amnesia caused by

excessive use of alcohol

• Others :– Alzheimer's disease can also affect memory and cognition. – Impaired memory can be a symptom of hypothyroidism