Working Memory • 131“Would you like to substitute spinach instead?” she wouldn’t know whether it was
being substituted for the broccoli or for the mushrooms. Thus, short-term processes are
needed not only for storage, but also for active processes like understanding conversa-
tions. Another example of an active process occurs when we solve even simple math
problems, such as “Multiply 43 times 6 in your head.” Stop for a moment and try this
while being aware of what you are doing in your head.
One way to solve this problem involves the following steps:(1) Visualize: 43
× 6
(2) Multiply 3 × 6 = 18.
(3) Hold 8 in memory, while carrying the 1 over to the 4.
(4) Multiply 6 × 4 = 24.
(5) Add the carried 1 to the 24.
(6) Place the result, 25, next to the 8.
(7) The answer is 258.It is easy to see that this calculation involves both storage (holding the 8 in memory;
remembering the 6 and 4 for the next multiplication step) and active processes (carrying
the 1, multiplying 6 × 4) at the same time. If only storage were involved, the problem could
not be solved. There are other ways to carry out this calculation, but whatever method
you chose involves both holding information in memory and processing information.
The fact that STM and the modal model do not consider dynamic processes that
unfold over time led Baddeley to begin considering alternatives to the modal model. In
addition, Baddeley noticed something else that was not explained by the modal model:
Under certain conditions it is possible to carry out two tasks simultaneously, as illus-
trated in the following demonstration.DEMONSTRATION Reading Text and Remembering Numbers
Keep the numbers 7, 1, 4, and 9 in your mind as you read the following passage:Baddeley reasoned that if STM had a limited storage capacity of about the length of a
telephone number, fi lling up the storage capacity should make it diffi cult to do other
tasks that depend on STM. But he found that participants could hold a short string of
numbers in their memory while carrying out another task, such as reading or even solving
a simple word problem. How are you doing with this task? What are the numbers? What is
the gist of what you have just read?According to the modal model, it should only be possible to perform one of these
tasks, which should occupy the entire STM. But when Baddeley did experiments involv-
ing tasks similar to those in the previous demonstration, he found that participants
were able to read while simultaneously remembering numbers.
What kind of model can take into account both (1) the dynamic processes involved
in cognitions such as understanding language and doing math problems and (2) the fact
that people can carry out two tasks simultaneously? Baddeley concluded that the short-
term process must be dynamic and must also consist of a number of components that
can function separately. According to this idea, the digit span task in the demonstration
(holding numbers in your memory) would be handled by one component while com-
prehending the paragraph would be handled by another component.
The model Baddeley proposed was fi rst described in a paper with Graham Hitch
(Baddeley & Hitch, 1974) and, as we will see, was later modifi ed to explain new fi ndings.
In this model, the short-term component of memory is called working memory. Working
memory is defi ned as a limited-capacity system for temporary storage and manipulationCopyright 2011 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.