BUILDING MEMORIES I:
ATTENTION AND REHEARSAL
• Themes
– Factors that influence encoding
• Presented information
• What you do with it
• What you know about it
• The context of the encoding episode
– In general, memory will be influenced by
• The quantity of practice
• The distribution of practice
• The quality of practice
– Informal strategies for learning
• What do you do?
ATTENTION AND LEARNING
• The unimportance of being earnest
(Hyde & Jenkins, 1969)
24 words presented
instructions about
recall
Encoding task:
rate pleasantness
detect # of e’s
incidental
intentional
16.3
16.6
9.4
10.2
• The importance of being awake:
• Simons & Emmons (1956)
– Word lists presented during sleep
– EEG recorded to confirm sleep
– Next day: recognition d’ = 0
• Tilley (1979)
– 20 pictures of concrete objects shown
before sleep
– Ten repetitions of object names at
different sleep stages
– Next day: better recall, recognition of
named objects
– But only for “shallow” stages of sleep
• Walker & Stickgold (2006)
– Resurgence of research on “sleepdependent memory processes”
• The importance of getting sleep
– Sleep deprivation and encoding
• Walker & Stickgold 2006:
36 hours of sleep deprivation
Incidental study of word lists
Recall two days later:
– REM deprivation and the brain
• Baseline EPSP, LTP down in hippocampus
• Nerve growth factor down “
“
• Sleep and Consolidation
– Greater activity in REM & SWS
• Following intensive study session
• Correlates with later retention
– Peigneux, et al. (2004):
• The importance of paying attention
– The classic “shadowing’ studies
(e.g., Moray 1959: 35 reps don’t help)
– Dual-task studies and divided attention
(Murdock, 1965)
– Are some attributes of events encoded
“automatically”?
• Frequency
• Recency
• Temporal & spatial distribution
– (Hasher & Zacks, 1979)
• Are these more a function of “implicit
memory” than explicit encoding?
• Evidence that even these can be
influenced by attention, age, etc.
AMOUNT OF PRACTICE
• Retention increases monotonically with
amount of practice
– Repetitions across lists (Ebbinghaus, 1885)
– Repetitions within list (Rundus, 1971)
• The Power Law of Practice
log(Y) = a * (log [practice]) + b
taking the “antilog” of each side:
Y = b * (practice)a
– Ubiquitous in declarative and procedural
learning
– A number of models can generate it
– E.g., Estes’ classic Stimulus Sampling
Theory (1960’s)
DISTRIBUTION OF PRACTICE:
THE SPACING EFFECT
The robustness of the
spaced-practice advantage
• Across days
– Spanish vocabulary (Bahrick & Phelps
(1987)
• Two sessions
• 0, 1 or 30 days between sessions
• Immediate test: no diffs
• 8 years later: 30-day is 2.5 times better
– Typing Skill (Baddeley & Longman,
1978)
• One- or two-hour blocks
• One or two blocks per day
• Spaced practice group learns twice as
fast
• Spacing within sessions
– The “lag” effect (e.g., Melton 1962)
e.g. Underwood (1970):
42 nouns for free recall, one/sec rate
1 to 4 presentations, massed or spaced
1
2
3
massed 15%
17%
17%
19%
spaced
31%
42%
47%
16%
4
• Limits to Spacing Advantage
– Immediate tests after study
– Implicit memory tasks
– Very-long lag between presentations
• The wonders of “expanded
rehearsal”
EXPLANATIONS OF THE
SPACING EFFECT
• Encoding variability and relational
processing
– Idea: increasing “retrieval paths”
– Spacing helps free recall > cued recall
– Forcing variability sometimes helps,
sometimes hurts, final recall
• Deficient attention (and its
consequences)
– Idea: massed presentations give
habituation, less attention and learning
e.g., Johnson & Uhle (1976):
repeat Underwood (1970), measure
“tone probe” secondary task RT:
1
spaced
2
3
4
321
330
328
238
223
206
282
massed
• Deficient Rehearsal
– Idea: less “covert” rehearsal if massed
– Spacing does increase overt rehearsal
– Spacing advantage even in incidentalmemory tasks
• Deficient Consolidation
– Idea: massed practice prevents full
consolidation
– Can it handle wide “scale” of spacing
effects?
• Retrieval practice
– Idea: spaced study gives “covert
retrieval” of prior encounter
– Forcing retrieval gives better memory
than study only (Carrier & Pashler, 1992)
– The Testing Effect (Gates, 1917)
• Long-term benefit from testing versus
studying
Spacing and context
• Verkoeijen, Rikers & Schmidt (2004)
Ss see 120 words per list
20 single, 20 massed rep, 20 spaced rep
Black on white, or olive, background (E1)
Black on city, or forest, background (E2)
40
Percent Recalled
–
–
–
–
35
same background
30
different background
25
20
15
10
5
0
spaced
massed
Type of practice
single
The Power of Testing Memory
• Retrieval practice’s advantages
– “If you read a piece of text through twenty times,
you will not learn it by heart so easily as if you
read it ten times while attempting to recite it from
time to time, and consulting the text when
memory fails” (Francis Bacon, 1620)
– Roediger & Karpicke (2006)
• Students study scientific prose
• Then restudy for 7 min, vs. free recall, no
feedback
• Final recall at 5 min, 2 days, 1 week
Proportion idea units recalled
90
80
Study, Study
70
Study, Test
60
50
40
30
20
5 min
2 days
Retention interval
1 week