Peterson & Peterson (1959)--The rate of forgetting in STM
·S's were given 3 consonants to try to remember
·S's were given a 3 digit number (394) &
asked to count backwards by threes from this number (e.g., 391, 388, 385, . . .
·After a variable amount of time counting, S's
were asked to recall the 3 letters.
Conclusion: This seems to indicate that STM fades away after approximately 12
seconds without rehearsal.
Waugh & Norman (1965) suggested that it could be that the counting
backwards is interfering with STM recall. They designed an experiment to
try to separate decay theories of forgetting from interference theories.
·S's were presented w/ lists of 16 digits. S's
task was to remember the prior presentation of the last digit and to recall the
digit that followed it in the list earlier.
·For example: 7 4 4 1 2 9 5 7 5 3 4 2 8 7 6 8
·The numbers were read at one of two rates: 1
digit per second or 4 digits per second.
Predicted Results if Decay Theory is correct.
Predicted Results if Interference Theory is correct.
Conclusion: Interference seems to play a bigger role in forgetting in STM
than memory decay. The type of interference found in this experiment is called retroactive
Proactive Interference also occurs.
·Proactive interference refers to
forgetting that occurs due to prior learning.
Keppel & Underwood (1962)
·They replicated the Peterson & Peterson Task
keeping the time delay constant (e.g. 12 seconds).
·They analyzed their data by trial number (1st
trial, 2nd trial, 3rd trial, etc.).
He performed the Peterson & Peterson Task using the letters B C P T V &
F M N S X and looked at the error patterns when S's recalled the wrong letters.
He found that 75% of the errors were from the same acoustical class suggesting
that STM mostly contains acoustical information.
However, Brooks (1968) showed that visual/spatial information must exist
Also, Wickens (1970) showed that semantic
information may be important to STM.
The Release from Proactive
Wickens replicated Keppel & Underwood's experiment but changed the category
of the memory items on the 4th trial for some subjects. (e.g., changing
from letters to words or vice versa).
Atkinson & Shiffrin suggested that information was transferred from STM to
LTM through rehearsal.
·Rehearsal = Verbal repetition of
Early research by Rundus (1971) supported this claim.
·Rundus conducted a standard learning paradigm in
which S's heard a long list of words to try to remember.
·S's were instructed to talk aloud while learning
·After the list presentation, S's counted
backwards by 3's for 30 sec. to clear out their STM.
·He found that the more times a S repeated a word
during learning, the greater that S's memory for that word was suggesting
repetition led to transfer to LTM
Craik & Watkins (1973) suggested that mere repetition wasn't enough to
tranfer information to LTM.
·In their expt, they required S's to only hold
one word in STM at a time, and they varied the amount of time the word was held
·S's were told to remember the last word they
heard that started with the letter G and were given a 21 word list.
·Rehearsal time was varied by manipulating how
long it was between words that started with G. (e.g., daughter, oil, rifle,
garden, grain, football, table, anchor, giraffe --"garden" would be
held for 1 second, "grain" for 4 seconds, etc.).
·After 27 lists, S's had to recall all the G
Results: No correlation was found between amount of time in rehearsal and later
In Baddeley's model, we see a shift away from emphasizing the structure of
memory to an emphasis on the processes of how information gets into and out of
Research examples: Baddeley & Hitch (1974)
Expt1 Methods: S's perform two tasks simultaneously.
·A difficult or easy standard STM task. Remember
& repeat either 6 random digits or 1,2,3,4,5,6 over and over.
·A simple reasoning task. S's had to judge the
veracity of simple sentences like:
oA is not preceded by B.
·S's hear a prose passage.
·S's see digits on a computer screen &
owrite them down as they see them or
owrite 6 of them down after seeing the 6th one
·S's are then given a prose comprehension test.
Conclusion: Performing mental reasoning and language comprehension utilize the
same mental resources as STM and should be thought of as involving many of the
Independence of the Visuospatial Sketchpad
and the Articulatory Loop:
Use tasks that occupy VSSP or AS but take little mental effort (i.e.,
Central Executive resources) and look at how these affect performing visual or
auditory STM tasks.
– Perceptual Vigilance task
– Articulatory Suppression task
These tasks disrupt STM performance in the same modality but not in the other
Individual differences in Working Memory
Feldman-Barrett, Tugade, & Engle (2004) showed that WMC is highly
related to how people do on a whole bunch of tasks.
Their findings across 20-30 publications is that WMC affects the amount of
automatic or controlled processes that people use.Individuals with high WMC use more
Controlled processes; individuals with low WMC use more Automatic processes.
This fits with a wide variety of dual-process models of cognition &