Sensory memory
Ch 5 p116-123
Information-processing approach
• Atkinson & Shiffrin (1968): Modal model of
memory
• Sensory memory
• Short-term memory
• Long-term memory
Sensory memory
• Brief retention beyond physical stimulus
• Senses
• Vision: iconic memory
• Auditory: echoic memory
• Purpose?
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•
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Persistence: beyond physical duration
Collect and hold until further processing
Integration
Provides stability for senses
Fill-in the blanks (e.g. blinks)
Iconic memory
• Real world examples
• Optical illusions due to retinal
afterimage
• http://michaelbach.de/ot/mot_strob/index.html
• http://michaelbach.de/ot/col_rapidAfterimage/index.html
Photography: shutter speed
1/30
1/500
Sperling (1960)
T
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C
P
K
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Iconic memory
• Sperling (1960)
• What is capacity of iconic memory?
• What is duration of iconic memory?
• Method
• Flash (40ms) letter array (3 rows, 4 letters/row)
• Whole report condition
• Partial report condition (auditory cue after display)
• Results
• Whole: 4.5 out of 12 (37.5%)
• Partial: 3.3 out of 4 (82%)
• Conclusions
• Memory of display decays rapidly
Delayed partial report method
• Figure 5.7 (p. 145)
Results of Sperling’s (1960) partial-report experiments.
Partial report CogLab
ISI (ms)
Percentage
recalled
20.0
55.55
100.0
54.26
300.0
49.18
1000.0
41.07
Spring ’12, N = 15
Averbach & Sperling (1961)
Averbach & Coriell (1961)
*
B T P O M W U C
Y S A D E H L K
Method: report letter near mark
Result: 75% accuracy = 12/16 items
What if mark is a circle?
Averbach and Coriell (1961)
• Question
• Can iconic memory be erased?
• Examine loss of information
• Method
• 2 rows, 8 letters/row for 50ms
• Visual cue: line above or below or circle
• Result
• Circle cue “masked” perception of the
letter.
• Conclusion
• Backward Masking: a later visual
stimulus interferes with earlier one
Echoic memory
• How would you study echoic
memory?
• Questions
• Methods
• IVs, DVs
• Hypotheses
Echoic memory
• What is duration of echoic memory?
• Darwin, Turvey, & Crowder (1972)
• Method
• “3-eared man procedure”
• 3 stimuli per location – each stimulus 1s
• Left ear, right ear, and both (“third ear”)
• Whole v. partial report (visual cue)
• Results
• Whole: average 4 out of 9
• Partial: average 5+ out of 9 (50%+)
• Conclusion
• More available than can be reported!
Darwin, et al. (1972)
Comparison
Iconic
Echoic
Echoic memory
• Duration of echoic memory
• Crowder (1982)
• Method
• 2 vowel sounds – same/diff?
• Vary gap
• Results
• <1s – more accurate
• >3s – flat accuracy
• Conclusions
• Echoic memory lasts up to 3s
Echoic memory
• Can echoic memory be erased?
• Method
• CogLab: suffix effect
• Hear stimuli in list
• Final auditory stimulus as cue to recall
• “Suffix”: zero or tone
• Results
• Tone-suffix: no change in performance
• Zero-suffix: 50% more errors on last item
• Conclusion
• New auditory info erased stimulus
• Or just increases list length
Suffix effect
F09: CogLab
• Listen then
recall 9 digits in
same order as
presented
• IV: Cue to recall
• ‘zero’ (suffix) or
tone (control)
Echoic memory
• Crowder and Morton (1969)
• Method
• CogLab: Modality effect
• View 9 digits – 2items/sec
• 3 conditions
• Silent vocalization
• Active vocalization (say out-loud)
• Passive vocalization (hear tape recording)
• Results
• Active/Passive: < 10% errors on last item
• Silent: 50% errors last item
• Conclusion
• Auditory trace assists memory for final item
Modality
effect
• Same graph
again!
Naatanen (1992) or
Sams, et al. (1993)
• Examine ERP of echoic memory
• Method:
• Are different sounds presented?
• Results:
• Increased negativity of ERP from 150200ms if different sounds
• “Mismatch negativity”
• ERP effect if delay between sounds
was < 10s
Pakarinen et al. (2007)
Echoic memory
• Why do we care?
• Allows more time to analyze
stimulus
• Able to process significantly more
• Practical implications
• Use silent rehearsal to slow rate
of decay
• Use to distinguish clinical
populations: e.g. schizophrenia
Javitt et al. (1997)
Sensory v. STM
Sensory memory
Short-term memory
• Capacity
• Capacity
• Duration
• Duration
• Unprocessed
• Accurate
• Passive
• Can be manipulated
• Can be inaccurate
• Active
• Iconic: 17+
• Echoic: 5+
• Iconic: 500ms
• Echoic: 2s
• 1-4 items
• 7 +/- 2 items
• 30s without rehearsal
Perception, attention or memory?
• Sperling
• Initial step in visual perception
• Haber (1983)
• Irrelevant for “normal” continuous
perception
• First 50ms of fixation
• Integrate information across
saccadic eye movements or time