Memory (Part 1) Sensory Memory and Short-term Memory Flashcards
What is Memory?
Memory is a set of systems for storing and retrieving information that is acquired through our senses
Memory contains mental representations of information that we have experienced, imagined and learned
“Learning is the process of acquiring new information, while memory refers to the persistence of learning in a state that can be revealed at a later time.” (Squire, 1987)
Memory in terms of three processes
- Encoding: converting information into a comprehensible form (getting information into memory)
- Storage: retaining information
- Retrieval: gaining access to information stored in memory
Memory in terms of four processes
- Acquisition: registers inputs in temporary sensory storage
- consolidation: creates a stronger representation over time
- Storage: maintenance of a permanent record to be used at later time
- Retrieval: utilisation of stored information to create a conscious representation, or to execute a learned behaviour
The multi-store model of memory
Atkinson and Shiffrin (1968)
Three separate stores:
Sensory memory: duration: ultra-short, capacity: large
Short-term memory: duration: seconds to minutes, capacity: limited
Long-term memory: duration: years, capacity: unlimited
Sensory Memory (George Sperling 1960)
He named the sensory memory store “Iconic Memory”
This store is characterised by a large capacity, but rapid forgetting, as demonstrated in his famous experiment
He was interested in how much information can be held in sensory memory
For this experiment, he used the “full vs. partial report” method
George Sperling Memory experiment results
For a very brief time all information must be held in memory
The partial report technique demonstrated that the capacity of iconic memory is quite large – most people can recall 3-4 items (the entire row)
By varying the onset of the cue it has been shown that after ~500ms, the memory trace decayed and items can’t be recalled
Echoic Sensory Memory
There is a similar modality specific memory store for sounds
Moray, Bates, and Barnett (1965) simultaneously presented sequences of consonants from different locations
Echoic memory is similar to iconic memory in that there is more information accessible than can be recalled
Echoic memory is different in that the trace lasts longer, up to 3-4 seconds
What is the function of sensory memory?
Sensory memory prolongs briefly presented stimuli to increase the chance that they will be present long enough to be attended
Attended information can then be transferred into the short-term memory (STM) store
Information in STM can be held for several seconds, integrated with information from other sources, and then transferred into long-term memory (LTM)
Short- term Memory (STM)
capacity limited (5+ or -2 pieces of information), duration seconds to minutes
Information is kept active via maintenance rehearsal (repeating information without ascribing meaning to it)
non-rehearsed information is lost rapidly via decay
Peterson & Peterson (1959) Experiment with consonants and counting on Short-term memory
Participants had to remember 3 consonants (e.g. CHM)
They prevented prevent rehearsal by counting backwards in 3’s from a given number until stop (e.g. 506 – 503 – 501… )
They also systematically manipulated the retention interval from 3 to18s
If not rehearsed, the items are forgotten after some seconds
The consonants are displaced from memory
Short-term memory Chunking (manipulates capacity of STM)
George Miller (1956) conducted a study on STM Capacity:
Participants had to perform a digit-span task: This tests the ability to recall a sequence of random digits in the order they were presented (serial recall)
He also systematically manipulated retention interval from 3 to 18s
He found that participants were able to recall more items when they could group information into meaningful units (“chunks”)
Chunking can increase the amount of information contained in STM
Participants can store seven (5+/- two) units of information
The Serial Position Effect (Primacy and Recency Effect)
Rehearsal mediates the transfer between STM and LTM
Primacy Effect: better recall for items at the beginning of a study list as items have been rehearsed and transferred to LTM
Recency Effect: better recall for items at the end of a study list as items presumed to be retained and still rehearsed in STM
Craik & Lockhart (1972) Levels of processing
Challenged the multi-store model and the role of maintenance rehearsal in transferring information to LTM
They proposed that processing that involves more interaction with previously stored knowledge increases the chance that the information will be preserved
Their key concept is Levels of Processing: “deep” vs. “shallow” processing
Deep processing v.s Shallow processing
deep processing:
- involves a reorganisation of the information
- formation of association
- creation of (interactive) mental images
Deep processing results in richer ‘network of associations’ and increases the likelihood of recall
shallow processing:
- simple repetition of material (rehearsal)
- processing of surface features (i.e. upper or lower case letters instead of meaning)
Levels of processing: Experiment by Craik and Tulving (1975)
Participants were given a list of words with three different tasks (they did not expect the memory task later on):
Task 1: structural processing (shallow) Is the word written in capital letters?
Task 2: phonological processing (medium) Does the word rhyme with another word X?
Task 3: semantic processing (deep) Does the word fit in sentence Y?
Then, after the “experiment”, they were given an unexpected memory task…
The questions was whether the first task led to different performance in the memory task
