Memory

What is Memory?

• Memory is a system that encodes, stores and retrieves information

– Process by which information is taken in, converted to meaningful patterns and then saved until such time as it is needed

– E.g., expectancies stored associations between behaviors and consequences that drive behavior

The Three Stages of Memory

The three Stages of Memory

• Sensory Memory

• Working Memory

• Long-Term Memory

Sensory Memory

• Real time capture of sensory stimuli– Iconic memory visual images– Echoic memory sounds

• Function Scan sensory information; select information to focus on and filter everything else out

• Capacity 12 – 16 items

• Duration .25 seconds

Sensory Memory

• Sperling– Designed a study to examine the capacity of

the sensory store

– Briefly presented a stimulus array; ask subjects to:

• Report everything you see• Report on specific information

D J B W

X H G N

T M L P

Report everything you see

X Q Y W

P L M G

S Q T V

Report contents of second row

Working (or Short-Term) Memory

• Mental work station

• Functions:– Selects information from sensory store on which to

focus attention– Temporary storage site for new information – Processes information so it can be transferred to

long-term memory

• Capacity 7 +/- 2

• Duration approx. 20 seconds

Long-term Memory

• Function Permanent storage site for all types of information

• Capacity unlimited

• Duration unlimited

Three Basic Tasks of Memory

• Encoding

• Storage

• Retrieval

Encoding

• Process of transforming, coding, or sorting information so that it is in a useable form

– E.g., like a card catalog, encoding involves cross-referencing information under multiple categories

Methods of Encoding

• Chunking putting multiple pieces of information together into meaningful groups; helps to expand the capacity of working memory

– E.g., Can you remember these numbers?

1 4 9 2 1 7 7 6 1 8 1 2

Methods of Encoding

• Rehearsal– Maintenance rehearsal involves repeating

information over and over• Good for maintaining in STM but not useful for

transferring to LTM

– Elaborative rehearsal connecting new information with knowledge that is already stored

• Good for transferring information from STM to LTM

Methods of Encoding

• Levels of Processing– Deeper processing results in better

remembering

• For example: encoding the word Horse– Visual (i.e., how it looks) -- It has a capital letter,

and is arranged cvccv.– Acoustic Sounds like course– Semantic an animal that eats hay that you can

ride.

Storage• Process by which information is

maintained in long-term memory

• Divisions of LTM– Procedural memory for mental

directions or procedures

– Declarative memory for facts and events• Episodic Stores personal information;

memory for events in your life• Semantic Basic meanings of words and

concepts

Retrieval

• Process by which information is accessed from long term memory so that is can be used or modified by new information

• Depends on how information was encoded and stored

Factors Affecting Retrieval• Depth of Processing retrieval is better

– the more deeply information is processed– The more connections that have been formed with

existing information

• Retrieval Cues Stimuli that help to bring a memory to consciousness

• Encoding specificity The more closely the retrieval cues match the cues present at encoding, the more readily the information will be retrieved

• Mood biases retrieval of information that is mood-congruent

Retrieval

• Implicit Recall – Memory that was not deliberately learned or was outside of conscious awareness

– Priming – process of providing cues that stimulate retrieval of implicit memories without awareness of connection between the cue and the retrieved memory

Retrieval

• Explicit – Memory that has been processed with awareness and requires effort and conscious awareness

– Recall Must produce previously stored information (Short answer question)

– Recognition Identify stimulus as having been presented previously (i.e., multiple choice)

H.M.

• Removed hippocampus and amygdala on both sides of brain to control severe epileptic seizures

• Result severe anterograde amnesia– Inability to form new memories– Unable to transfer information from short-term to long-

term memories

• Memory deficits are uniquely for declarative but not procedural memories

Forgetting or Memory Lapses

• Serial Position Effect– First and last items on a list block retrieval of

information in the middle

• Context – dependent learning– Memory fails when context at retrieval differs from

context at encoding

• Reconstructive nature of memory– Take in information, discard details, organize rest in

meaningful patterns– At retrieval, reconstruct details based on fragments

that are stored