What is memory?
The mental process of registering,
storing and retrieving information.
There are different types of memory.
Who can remember what they were
wearing on the first day of this term?
Do you remember what you ate last
Friday for lunch?
three types of memory
• Sensory memory
• Short-term memory
• Long-term memory
Both STM & LTM are studied in terms of:
Encoding – Making sense of information
Capacity – How much information
Duration – How long information can be stored for
Sensory Memory
Duration: Seconds
Capacity: Small instant
Encoding: not applicable
Short Term Memory
• Duration: 18-30
seconds
• Capacity: 7+/- 2
items
• Encoding: Acoustic
Short Term Memory
Duration
18 – 30 seconds
• Peterson & Peterson suggested
that where information is
continually rehearsed it can be
stored in the short-term memory
indefinitely but is lost as soon as
interference blocks rehearsal.
Short Term Memory
Duration
18 – 30 seconds
• Ever been given a telephone number and had to keep
repeating it avoiding all distractions until you wrote it
down to prevent forgetting it then you were experiencing
Maintenance Rehearsal?
• Reitman (1974) Short duration is due to displacement; as
new information is coming into the short-term memory it is
kicking out the previous information due to its limited
capacity (7 +/- 2 chunks).
• Information decays (fades away) rapidly in short term memory
unless rehearsed.
Short Term Memory
Capacity
7+/- 2
Miller’s Magic 7 +/-2
Miller (1956) The magical 7 +/-2.
The STM can hold on average between 5 & 9 items of
information.
Chunking: Grouping the items together into chunks.
Telephone number: when you remember it you often recite
a group of the numbers as together e.g. 01253 720 742,
rather than 01255364289.
Meaningful chunks are even easier to remember:
CBC, FBI, NBC
Long Term Memory
• Duration: Lifetime
• Capacity: Limitless
• Encoding: Semantically
Long Term Memory
Duration
Bahrick (1975)
Investigation of the duration of very-long-term memory (VLTM).
Tested the duration by testing recall of real-life information.
Participants included 392 American ex-high school students aged
17-74.
Recall was tested in four ways:
1. Free recall of the names of as many of their
former classmates as possible.
2. A photo recognition test where they were
asked to identify former classmates in a set of
50 photos, only some of which were their
classmates.
3. A name recognition test.
4. A name and photo matching test.
• 90% accuracy in FACE AND NAME RECOGNITION after 34
YEARS
• 80% accuracy for NAME RECOGNITION after 48 YEARS
• 40% accuracy for FACE RECOGNITION after 48 YEARS
• 60% accuracy for FREE RECALL after 15 YEARS
• 30% accuracy for FREE RECALL after 30 YEARS
Classmates are rarely forgotten, but cues are sometimes
needed.
Recognition was better then recall.
Long Term Memory
Encoding
Procedural memories that are concerned with
how to do things
*Declarative memory, which is how we remember what
things mean, and can make links between a stimulus and
previous experience.
SEMANTIC processing: The LTM
encodes according to meaning.