Capacity Flashcards
Define capacity
The amount of information that can be held in a memory state
what is the capacity for Short term memory(STM)
> Capacity is between 5-9 items on average
What is the capacity of Long term memory(LTM)
it has potentially unlimited capacity
can store memory for lifetime
Jacobs Research on capacity-STM
(Digit span-read 4 digits to p)
Jacobs
Jacobs(1887)-measured digit span
Researchers read out 4 digits & p called them out loud in order
> if correct researchers read out 5 digits…
>until p cannot recall order correctly
>indicating the individuals digit span
> Jacobs found mean span for digits across all p was 9.3 items
>Mean span for letters was 7.3
Research on capacity-STM
(Span of memory & chunking)
Miller
Miller
Miller(1956) made observations of everyday practice
>noted that things come in sevens
> seven notes on musical scale, seven days of the week..
>Miller thought the span (capacity) of STM is 7 items +-2
>however this can be improved by chunking ,notes ppl also can recall five words as easily as recalling 5 letters- by chunking info
>chunking-grouping sets of digits or letters into units or chunks
Jacobs study(digit span) on capacity lacks validity
Jacobs study conducted a long time ago
early research in psych lacks adeqaute control
e.g some p may been distracted while being tested, so didnt perform as well
results not valid because of confounding variables that not controlled
counterpoint: however results of this study have been confirmed in other research supporting its validity
Miller(chunking)-overestimated STM Capacity
Limitation
Miller may have overestimated the capacity of STM
Cowan reviewed other research, concluded that capacity of STM was only about 4 chunks
Suggests lower end of MIllers estimate-5 items is more appropriate than 7 items
Also
research into short-term memory did not take into account other factors that affect capacity. For example, age could also affect short-term memory
