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?

• 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 B W C

P K S H

D M R L

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 150-

200ms 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

• Capacity

• Iconic: 17+

• Echoic: 5+

• Duration

• Iconic: 500ms

• Echoic: 2s

• Unprocessed

• Accurate

• Passive

Short-term memory

• Capacity

• 1-4 items

• 7 +/- 2 items

• Duration

• 30s without rehearsal

• Can be manipulated

• Can be inaccurate

• Active

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