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Practice

Amount, specificity, variable, constant...

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Performance & learning

• What is learning, really?– Performance is observed, learning inferred– Performance can improve without improved

learning– Learning can improve without improved

performance

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Amount of practice

• Do we become less dependent on the environment, or more?– Important implications – should you practice

powerlifting in front of a mirror to aid form? (Proteau & Temblay, 1998)

– Motor program theories could suggest you should• Repeat, repeat, repeat, and the process becomes

increasingly independent of sensation (“you could do it with your eyes closed” - http://www.youtube.com/watch?v=Yshe4BcN_Mg).

– Proteau and colleagues thought otherwise...

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Amount of practice

• As we learn, do we rely less on feedback?• Proteau’s task (1987, 1992)...

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Amount of practice

• As we learn, do we rely less on feedback?• Proteau’s typical paradigm...

– Task: 90cm movement in 550msec– Condition 1: 200 trials with vision– Condition 2: 2000 trials with vision– Test condition: No vision

Has also used walking (see next slide), force control, and others

Sometimes as little as 20 vs. 200 trials too.

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Amount of practice

• 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

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Amount of practice

• 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”

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Amount of practice• 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

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Variability of practice

• 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?

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Variability of practice

• 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

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Variability of practice

• 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, and

Schmidt & Lee’s texts for more recent summaries.– Does not imply that the governing theory is accepted

• Now as for organization of variability...

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Contextual interference

Practice order (3 tasks – A, B, and C)

Blocked

All A’s

…then all B’s

…then all C’s

SerialA

CB

Random

Who knows – it’s

random!

Amount of contextual interference

Low High

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Contextual interference

• 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

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Contextual Interference effect

• 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

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Contextual Interference

• 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?

– “inter-task” versus “intra-task” processing.

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Contextual Interference

• 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)

Recall worsens as interval “A” increasesA

A

Recall improves (!) as interval “A” increases

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Contextual Interference

• Which hypothesis is best supported?

– Please note I’m not saying this is proof of one theory’s predominance – it’s too complicated for that (think external validity!) – but it is interesting evidence in this instance.

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Contextual Interference

• Predictions, and task

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Contextual Interference

• A typical trial pattern (showing when TMS is applied)

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Contextual Interference

• Which hypothesis is best supported?Blocked practice

groups unaffected by TMS

Random practice groups affected

by TMS

Blocked Groups Random Groups

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Contextual Interference

• Now for something completely different

We’ll see that these findings may severely limit the generalization of the CI effect

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Contextual Interference

• Task:

– Notice: overall duration varies across tasks; relative timing does not

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Contextual Interference

• 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

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Contextual Interference

• Findings– Experiment 1:

• The more consistent the practice type, the better people perform in retention and transfer

• Here, ratio feedback was provided for all groups (i.e. how well did the person do in performing the required rhythm?)

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Contextual Interference

• Experiment 2:– Feedback type has a radical effect

on this outcome– Hard to grasp, but depending on

feedback, effect is almost reversed– Generally, whatever results in

stability of RT during practice works (random practice with segment feedback did this, & so did blocked practice w/ratio feedback)

– Implication is that random practice is not good for learning tasks that require new relative timing patterns...

– ...but it is good if only absolute timing is required to change.

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Contextual Interference

• Applied work (e.g. – there’s lots more)...http://www.youtube.com/watch?v=CIG3El76ltg&feature=related A task with

“switched” relative timing

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Contextual Interference

• 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)

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Contextual Interference

• Since then...– Still celebrated as a general effect (in some places)

• 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)• Exceptions?

– Smith & Davies (1995, see also Smith, 2002, Smith et al, 2003) may be a result of negative transfer rather than CI (though this certainly matters too).

– See Barreiros, Figueiredo, & Godinho (2007) for a review of applied work. They say successful applications are somewhat rare (c. 40%)

• Subsequent work emphasizes the disconnect between simple and complex tasks (see next slide)

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Contextual Interference

• Complexity as a moderator (for CI & others)

A good review paper for the final

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Contextual Interference

• Different neural substrates responding to different practice structures?

TMS again, used this time to disrupt

particular brain sites (published in 2010)

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Contextual Interference – concluding comments

• So what does all that mean?– There do seem to be fundamental differences in

the brain’s reaction to the different practice types– These differences seem to be associated with

different memory activities– Could be that random practice enhances recall-

retrieval practice, while constant (or blocked) practice does not enhance recall-retrieval, but does a better job of allowing people to learn new movement patterns.

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Part vs. Whole practice

• 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.

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Part vs. Whole practice

Sections broken down by 3 mastery levels

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

1 2 3 4 5 6 7 8 9 10

Blocks of 40 attempts

Ave

rage

# c

atch

es 11am Beginners11am Intermediates11am Masters12.35pm Beginners12.35pm Intermediates12.35pm Masters

11am class: move through practice stages quickly (get to the full juggling phase as soon as possible)

12:35pm class: practice each stage thoroughly (master each stage before moving on)

Similar findings have been published by Knapp & Dixon, 1952.

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Part vs. Whole practice

• 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– Task complexity and organization (Naylor and

Briggs, 1963)• More recent research...

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Part vs. Whole practice

• Part/whole practice for Polyrhythms

Unimanual works well regardless of

training type

Polyrhythm does not benefit from

part practice