Practice
Chapter 5
Performance & learning
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Performance is observed, learning inferred
Performance can improve without improved
learning
Learning can improve without improved
performance
• What is learning, really?
Amount of practice
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Do we become less dependent on the
environment, or more?
• Important implications – do you practice
powerlifting in front of a mirror to aid form?
(Proteau & Temblay, 1998)
Amount of practice
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As we learn, do we rely less on feedback?
Proteau’s task (1987, 1992)...
Amount of practice
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As we learn, do we rely less on feedback?
Proteau’s typical paradigm...
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•
•
•
Task: 90cm movement in 550msec
Condition 1: 200 trials with vision
Condition 2: 2000 trials with vision
Test condition: No vision
Sometimes as little as
20 vs. 200 trials too.
Has also used walking
(see next slide), force
control, and others
Amount of practice
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As we learn, do we rely less on feedback?
Typical Results:
The full vision practice condition
typically transfers to a no vision
condition badly, and this gets worse
as full vision practice increases
Amount of practice
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As we learn, we seem to rely more on the
information that is present and used when
we learn
• For the powerlifting form example – mirrors not a
good idea (Proteau & Tremblay, 1998)
• Also think of learning to type, drive (shifting gear),
play piano (watching fingers) and so on
• “learning is specific to the source or sources of
afferent information that are more likely to
ensure optimal performance”
Amount of practice
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More recent findings:
• Weak vs. strong visual cues
•
(still a reaching task) –
weak vision transfers as
well as no vision to a no
vision condition
Weak vision encourages
processing of other sources
of information like
proprioception
Amount of practice
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More recent findings:
• Ball interception –
•
touch the interception
point of a moving ball
with the index finger
Two conditions: full
vision, or ball only
Amount of practice
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More recent findings:
• Ball interception – touch
•
the interception point of a
moving ball with the index
finger
Two conditions: full vision,
or ball only
Normal specificity effect
when transferring to
practiced trajectories
Effect disappears
in new trajectories
Variability of practice
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Imagine you’re trying to teach catching
• Should you make it as simple as possible, by
choosing only one type of ball, one type of throw,
one catching technique…etc…
• Or not?
Variability of practice
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Schema Theory (Schmidt, 1975)
• More variability means more generalized schema
for learning
• Like a regression rule
• Your performance of the right movement
depends on the proximity of previous behavior to
the desired behavior
Variability of practice
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Supported?
• Generally, I’d say so, provided key assumptions
are met
• Are the participants genuinely novices?
• Is sufficient practice given to form a strong enough
prediction rule?
• Is prediction of a novel version of the task ultimately
required?
• See Schmidt and Shapiro (1982) for a summary
• Does not imply that the governing theory is accepted
• Now as for organization of variability...
Contextual interference
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Practice order (3 tasks – A, B, and C)
Blocked
Random
Serial
A
All A’s
…then all B’s
…then all C’s
Low
B
C
Amount of contextual
interference
Who knows
– it’s
random!
High
Contextual interference
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Practice order (3 tasks –
A, B, and C)
• Stimulus light goes off
• Color signifies which
movement pattern to
perform
•
•
•
•
Pick up tennis ball
Knock down barriers
Replace tennis ball
RT and MT measured
Contextual Interference effect
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From the classic study
(Shea & Morgan, 1979)
Practice – Low CI is
better (time is being
measured, so smaller
scores are better)
Retention – High CI is
better
Contextual Interference
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Theory
• 2 primary hypotheses
• Elaboration
• Compare the sequence of tasks practiced within blocked
and random practice – what kinds of comparisons
between or among the tasks are promoted by each type
of practice?
Contextual Interference
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Theory
• 2 primary hypotheses
• Action plan reconstruction
• Compare the sequence of tasks practiced within blocked
and random practice – how long, on average, do you
have to wait before the task is repeated in each practice
order?
• Brown-Peterson (1958), Peterson-Peterson (1960)
A
Recall worsens as
interval “A” increases
Recall improves (!) as
interval “A” increases
A
Contextual Interference
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Some research examples, and some
conclusions...
http://www.youtube.com/watch?v=CIG3El76ltg&feature=related
Contextual Interference
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Smith & Davies (1995)
• Used a Pawlata roll
• Compared progressive part learning of a full roll with
either alternate (high CI) or blocked (low CI) practice
• All transferred to both a full and a half roll one week
later (score is 5 - average # attempts prior to success)
Contextual Interference
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Now for something completely different
(...and quite a bit more difficult)
We’ll see that these
findings may severely limit
the generalization of the
CI effect
Contextual Interference
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Task:
• Notice: overall duration varies across tasks;
relative timing does not
Contextual Interference
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Task:
• With this task, you can
vary overall duration
without varying rhythm
• see previous slide
• Or both
• Or vice versa
• E.g.
• 300-200-400
• 400-300-200
• and 200-300-400
Contextual Interference
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Findings
• Experiment 1:
• The more consistent
the practice type, the
better people perform
in retention and
transfer
Contextual Interference
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Findings
• Experiment 2:
• Feedback type has a
radical effect on this
outcome
• Hard to see, but
depending on fdbk,
effect is almost reversed
• Generally, whatever
results in stability of RT
during practice works
(random practice with
segment fbdk did this, &
so did blocked practice
w/ratio fdbk)
Contextual Interference
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Since then...
• Still celebrated as a general effect
• Does not seem to be the case
• Shea’s (& colleagues) work clearly important
• Findings largely limited to overall timing (simple
adaptations of already known movements)
• Smith & Davies (1995, see also Smith, 2002, Smith et al,
2003) may be a result of negative transfer rather than
CI
• But these things matter too!
• Subsequent work emphasizes the disconnect between
simple and complex tasks...
Contextual Interference
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Complexity as a moderator (for CI & others)
A good review
paper for the
final
Part vs. Whole practice
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Segmentation, fractionation, simplification,
component interdependence...
• Do the parts fit together naturally, or can they be
easily separated?
• Think of a free throw – should you practice the knee
movement and the arm movement separately?
• Juggling...from the annals of 257 (Spring 2000) – Knapp
& Dixon (1952) revisited.
Part vs. Whole practice
Sections broken down by 3 mastery levels
11am class: move through
practice stages quickly (get
to the full juggling phase as 45.0
soon as possible)
40.0
Average # catches
12:35pm class: practice
35.0
each stage thoroughly
(master each stage before 30.0
moving on)
25.0
Similar findings
have been
published by
Knapp & Dixon,
1952.
11am Beginners
11am Intermediates
20.0
11am Masters
12.35pm Beginners
15.0
12.35pm Intermediates
12.35pm Masters
10.0
5.0
0.0
1
2
3
4
5
6
7
Blocks of 40 attempts
8
9
10
Part vs. Whole practice
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In this case, part practice of juggling didn’t
work well
Seems that the skill is highly organized, and
as such should not be practiced in parts
See also Hautala (1988): scarves not a good
idea.