Sensory and Short Term Memory (Chapter 5) Flashcards Preview

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Modal model of memory

Input -> sensory memory -> short term memory -> (and backwards) long term memory
From short term memory: rehearsal (control process; keeps info active in STM), output


Sensory memory

Large capacity
Short duration
Purpose: collect info, hold info, fill in the blanks


Persistence of vision

Ability to connect visual input from the world amongst distractions (filling in missing sensory information)
Examples: not being aware of blinking, seeing a sparkler trail, perceiving movies as continuous motion


Sperling's experiment on duration of sensory memory

Whole report condition: flashed a matrix of letters for 50 ms (participants could see all letters, but could only remember 1 row on average)
Partial report condition: flashed matrix of letters, followed by tone cuing which row to recall (performance increased)
Delayed partial report condition: half second or full second delay prior to hearing tone (performance decreased)
Conclusion: sensory memory has large capacity, but short duration


Echoic sensory memory

Auditory sensory memory: lasts about 2 seconds
Longer than iconic sensory memory (visual sensory memory)


Short term memory

Capacity: 4-9 items
Duration: 15-20 seconds
Purpose: transfer "now" into LTM


Peterson and Peterson task: measuring the duration of STM

Presented 3 consonants together (devoid of meaning)
As soon as 3 letters were presented, had participants count backwards by 3's (prevent rehearsal)
The longer the duration of counting, the less the remembrance
Without rehearsal, not much is left after 20 seconds


Factors important to duration of STM

Rehearsal (increases)
Forgetting/decay (decreases)
Interference (decreases; more empirically supported than decay: new memories take place of old)


Proactive interference

Previous knowledge interferes with new


Release from proactive interference

Performance on a specific task goes down after many trials, but when task switches, performance goes back up again


Retroactive interference

New knowledge interferes with old


Digit span experiment

Have people recall successively increasing lists of numbers
Most people have a digit span between 5 and 9 digits (7 plus or minus 2 rule, which applies to most items)


Factors that influence capacity of STM

Defining an item (digits, consonants, words, etc.)
Chunking (grouping things together into a meaningful unit- increases STM)
Expertise (better STM when using meaningful units)


Chase and Simon's chess study (measuring expertise effects on STM)

Presented participants (chess experts and novices) with actual game positioning or random positioning of pieces and gave them 5 seconds to memorize positions
Experts were better at placing chess pieces only when positioning was based on an actual game