Control processes

• The kinds of mental processes carried out on a memory

• 3 main types– Encoding processes– Retention processes– Retrieval processes

Encoding

• “encoding” – process by which information is put into the correct form (or code) for the memory

• More generally, encoding means storing information in a memory

• E.g., in STM, encoding could be “chunking” (putting information into chunks)

Retention

• Retention = keeping information in memory

• E.g., in STM, we do “rehearsal” (repeat information in our minds) to keep info

Retrieval processes

• Retrieval = bringing information out of a memory so that it can be used in a task

• E.g., must “search” your memory for information

metamemory

• Metamemory = your knowledge of your knowledge

• E.g., most people know that they DO NOT KNOW the names of all presidents in order

Memory Scanning experiment

• Sternberg, 1966

• Aka, memory search

• RT study of how quickly people can tell whether a single letter was one of a set of letters they just saw

• In other words, people store a set of letters in STM, then they search STM to see if another letter is in there

Timeline

F K LM T

Letter set(memory set)

Delay(a few secs)

L

probe

Respond“yes”

RT

Serial and parallel search

• Looking through items one-by-one is serial (i.e., in a series) – slow

• Look through all of the items at the same time (look at all letters simultaneously) – parallel - faster

manipulation

• Varied the number of items in memory set (small number of items larger number of items)

• Number of items in memory set size

• If search is serial, then increasing set size will increase RTs

• If search is parallel, then increasing set size will NOT affect RTs

Prediction for parallel search

Prediction for serial search

Shows serial search

“yes”

“no”

Not self-terminating

More on serial search

• E.g., looking for “L” and “L” is the middle item in STM

• Best thing to do when “L” is found (most efficient) is to stop and say “yes” (self-terminating search = stop when you find what you’re looking for)

• On average, must search ½ of items to find item that is in there search fewer items on “yes” cases than on “no” cases

Exhaustive serial search

• Exhaustive = look through all of the items in STM even after you’ve found what you’re looking for

• Search all items on “yes” cases and all items on “no” cases “yes” RTs = “no” RTs

• Not very efficient, but it is how our mind works (could be “ballistic” – can’t stop once it starts)

Long-Term Memory

• Capacity, duration, code

• LTM has unlimited capacity, infinite duration, uses all codes

• E.g., concept of democracy is representing in LTM via semantic code

Conway et al. (1991)

• P. 115 in Reed text

• Study of how long people remember information from cognitive psychology class

• Study of the duration of long-term memory

• Retention intervals from 3 mos. To 125 mos.

• Material remembered even after 10 years

Two types of recall tasks

• Serial recall vs. free recall

• Serial recall = remember order of items

• Free recall = don’t remember order, just the items

The Free Recall Experiment

• Present material to-be-learned (typically, a list of words)– List size within 7+/-2 (testing STM) (subspan)– List size > 7+/-2 (testing LTM) (supraspan)

• Retention Interval or delay– RI really short (< 30 secs) (testing STM)– RI > 30 secs (testing LTM)

• Then, the test (retrieval items in any order they want)