Cognitive Psychology Lecture Notes (STM)

Sensory Memory and STM

Sensory Memory

permits the trace of a stimulus to “linger on” for further processing

Why Sensory Memory?

we need to integrate information across time and space

we need to keep a brief record in order to select important stimuli for further processing (e.g. selective attention)

may provide a stability to visual world despite constant eye movement

Types of Sensory Memory

iconic memory: visual sensory memory

echoic memory: auditory sensory memory

Iconic Memory

visual information = icon
visual information automatically registered in iconic memory
Duration = icon lasts .5 s

Sperling (1960)

Hypothesis: mental picture of display disappeared / faded by the time you were able to respond

Design: whole report (report all items)

partial report (Ss heard high, med. or low tone; they reported corresponding top, middle, or bottom row of display)

Results: whole report = 4.5 items

partial report = 9 items

(accuracy rate X # letters in display)

(100% X 9 items = 9 items)

in partial report, with longer delays between stimulus presentation and sounding of the tone to report, accuracy decreased to 4.5 items (whole report levels) Fig. 4.1

Conclusion: icon fades after 1/2 second

provides a framework for info-processing - info is held for a brief amount of time before that info is processed further (stages of processing - Atkinson-Shiffrin)

Echoic Memory

auditory information = echo
auditory information automatically registered in echoic memory
Duration = echo lasts 2 s

Darwin, Turvey, Crowder (1972)

“three eared man” procedure (adaptation of Sperling’s procedure)
J 4 T 3 M Z A 5 2 (simultaneous presentation)
| | |
left middle right
replicated Sperling’s pattern of results, but maximum number of items recalled was 5 items and echo lasted for 2 s

Short-Term Memory

Theoretical Aspects:

proactive interference
span of STM
chunking

temporary storage of information: we forget information from STM after 30 seconds (unless we rehearse)
limited capacity (two views):

number of units:

digit span & the WAIS-III
Miller’s Magic Number
“7 plus or minus 2”
items can be organized into larger units called chunks

pronunciation times:

verbal trace endures for a limited time

Chad, Sweden, Greece, Cuba, Malta --> 4.2 items recalled

Indonesia, Somalia, Afghanistan, Argentina, Venezuela --> 2.8

Two Types of Chunking

1 4 9 1 6 2 5 3 6 4 9 6 4 8 1

combine items that are close together in time or space

1491 625 3649 6481

utilize information from LTM

1 4 9 16 25 36 49 64 81

Proactive Inhibition (Interference)

old material interferes forward in time learning new material
PI occurs only with related material
Practical Example: abnormal psych & theories of personality

Release from PI

if one changes the learning material to unrelated material, performance on memory tests returns to normal
Practical Example: studying same material...take a break!!

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