Post on 30-Dec-2015
Chapter 4
Skill Memory: Learning By Doing
4.1
Behavioral Processes
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4.1 Behavioral Processes
• Qualities of Skill Memories
• Expertise and Talent
• Practice
• Unsolved Mysteries—Why Can’t Experts Verbalize What They Do?
• Transfer of Training
• Models of Skill Memory
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Qualities of Skill Memories
• Skill—an enduring ability that develops with practice over time.
• Skill memories: Cannot always be verbalized
Unconsciously acquired and retrieved
Basis for memories of events and facts
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Comparison of Memories for Skills, Events, Facts
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Perceptual-Motor Skills
• Perceptual-motor skills—learned movement patterns guided by sensory inputs. Enduring abilities developed with practice.
• Closed skills—involve established movements (ballet, diving, gymnastics).
• Open skills—respond to environmental changes (swing dancing, soccer, hockey).
• Any skill lies somewhere on the continuum from closed to open.
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Cognitive Skills
• Cognitive Skills—emphasize problem solving or applying strategies (e.g., Tower of Hanoi puzzle).
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Cognitive Skills
• Tool use involves perceptual-motor and cognitive skills. Chimpanzees crack nuts with stones.
Dolphins carry sponges to protect themselves from injury while foraging for food.
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Cognitive Skills
• birds
• http://www.youtube.com/watch?v=xwVhrrDvwPM&NR=1
• chimps
• http://www.youtube.com/watch?v=5Cp7_In7f88
• http://www.youtube.com/watch?v=SYpDgd29BAI
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Expertise and Talent
• Talent—mastering a skill with little effort (a “gift”).
• Expertise—performing a skill better than most people.
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Nature and Perceptual-Motor Skills
• Rotary pursuit task—a task where the user must hold the end of a pointed stick above a target on a rotating disk.
• Twins learned a rotary pursuit task. Skills of identical twins reared apart became more
similar.
Skills of fraternal twins reared apart became less similar.
Genetic differences may become more apparent with practice.
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The Rotary Pursuit Task: Effects of Practice on Performance
(b, c) Adapted from Fox et al., 1996.
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Perceptual-Motor Skills
• Researchers often study athletes and chess masters.
Games require a variety of perceptual-motor and cognitive skills; diverse levels of expertise.
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Perceptual-Motor Skills
• Researchers often study athletes and chess masters.
Chess masters quickly focus on key board locations, empty squares, relevant chess pieces; amateurs slowly scan many locations.
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Practice
• Knowledge of results—performance feedback Performance feedback improves practice
effectiveness.
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Practice
• The faster and more often you perform a skill the better you become.
• Without knowledge of results, learning stalls….
• http://www.youtube.com/watch?v=3PycZtfns_U&NR=1
• http://www.youtube.com/watch?v=E1oMCES56a4&feature=related
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Acquiring Skills
• Power Law of Learning—for perceptual-motor skills, learning first occurs rapidly, then slows, following a predictable pattern. More proficiency = less room for improvement
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Acquiring Skills
• Feedback can improve the effects of practice; not all feedback is equally helpful.
• The kind of feedback can determine how practice effects performance. e.g., in simple tasks:
Frequent feedback produces good short-term, but mediocre long-term performance.
Infrequent feedback yields mediocre short-term, but better long-term performance.
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Effects of Practice and Feedback on Skill Performance
(a) Adapted from Singley and Anderson, 1989; (b) adapted from Hatze, 1976.
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Acquiring Skills: Apportioned Effort
• Massed practice = concentrated practice Better short term retention
• Spaced practice = practice spread out over several sessions Better long term retention
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Acquiring Skills: Practice Conditions
• Constant practice = repeatedly practicing the same skill under the same conditions.
• Variable practice = practicing a skill in varied conditions.
• Optimal practice schedules are debatable.
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Implicit Learning
• Implicit learning—learning without direct awareness One can incidentally learn an underlying skill that
facilitates performance.
• Serial reaction time task—participants learn to press one of four computer keys from visual cues. Cues are in random or repeating patterns.
Participants show quicker performance on repeated patterns without pattern awareness.
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Serial Reaction Time Task and Implicit Learning
Adapted from Exner et al., 2002.
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Implicit Learning and Anterograde Amnesia
• Inability to form new episodic and semantic memories. Example: H.M. (developed anterograde amnesia
after surgery to reduce seizures)
• Patients can learn new skills.
• Patients do not verbally recall their practice trials.
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Implicit Learning
• Currently, no way to assess whether implicit learning is more likely in perceptual-motor than cognitive skill learning.
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Retention and Forgetting
• Skill memory is developed through practice.
• If we don’t use a skill, the skill is vulnerable to skill decay.
• Skill memory is subject to interference: Proactive Interference = difficulty learning and
remembering newer material
Retroactive Interference = difficulty remembering older material
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Unsolved Mysteries—Why Can’t Experts Verbalize What They Do?
• Experts (e.g., dancers, musicians, mathematicians) may: Have conscious access to information about their
skills.
Experience language constraints that prevent them from translating information into words.
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Unsolved Mysteries—Why Can’t Experts Verbalize What They Do?
• Many experts develop special communication with other experts. A unique language describes specific skills for
precise replication (e.g. complex dance movements or musical notation).
For example, demonstrating a complex dance movement to another dance expert may facilitate transfer of information.
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Transfer of Training
• How well might you perform a skill in a context that is different from the context at encoding?
• In some cases, skill memory is so specific introduction of additional cues can disrupt performance.
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Transfer of Training
• Transfer specificity—restricted applicability of learned skills to specific situations
• Encoding and subsequent practice in a certain context might lead to transfer specificity, which limits transfer of training. Thorndike’s identical elements theory
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Models of Skill Memory:Motor Programs and Rules
• In initial learning of a new skill, we tend to follow a set of rules (declarative).
• With practice: Steps become automatic (motor programs).
Attention to the declarative rules become unimportant.
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Stages of Acquisition
1) Cognitive stage—full attention to instructions, models, feedback
2) Associative stage—need cues, reminders for actions that are part of the skill
3) Autonomous stage—motor programs using less attention; loss of the ability to verbalize process
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Fitt’s Three-Stage Model of Skill Learning
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4.1 Interim Summary
• Skill = ability that can be improved over time through practice. Closed skills = predefined movements, never vary.
Open skills = movements in response to predictions about change in circumstance.
• Practice can decrease effects of experience and increase effects of genetic influence. Performance feedback critical to practice effectiveness.
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4.1 Interim Summary
• Power law of learning—with practice, time required to complete a task decreases at a diminishing rate. Law of diminishing returns
Holds for many cognitive or perceptual-motor skills.
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4.1 Interim Summary
• Massed practice = better short-term performance.
• Spaced practice = better long-term retention.
• Constant practice = skill repetition in fixed conditions.
• Variable practice = skill practice in varied contexts. More improvement with variable practice.
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4.1 Interim Summary
• Implicit learning = skill learning without conscious awareness. Tested with serial reaction time task.
Studied in patients with amnesia.
• Thorndike’s identical elements theory: transfer of skill to new situations depends on identical elements between learning context and new situations. Skill decay = unused learned skill is lost.
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4.1 Interim Summary
• Changes in skill memories with extended practice may occur in stages. Cognitive stage—skill is encoded through active
thinking.
Associative stage—skill is performed using stereotyped actions.
Autonomous stage—skill has become a motor program.
4.2
Brain Substrates
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4.2 Brain Substrates
• The Basal Ganglia and Skill Learning
• Cortical Representation of Skills
• Learning and Memory in Everyday Life— Are Video Games Good for the Brain?
• The Cerebellum and Timing
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Brain Substrates
• Neuroscientists hope to associate skill acquisition stages with changes in brain activity.
• Spinal cord and brainstem control and coordinate skill movements.
• Regions involved in sensation and perception (including sensory cortices) also involved in information processing during skill learning.
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Brain Regions that Contribute to Skill Learning
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Basal Ganglia and Skill Learning
• Basal ganglia (BG)—clusters of neurons at base of forebrain, close to hippocampus Relay sensory information from cortex to
thalamus and brain stem.
Involved in activation and control of movement velocity, direction, and amplitude.
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Learning Deficits after Lesions
• Rats with BG damage easily find food in radial mazes. However, in illuminated versus non-illuminated maze arm trials: BG damaged rats Have trouble finding food
placed only in illuminated maze arms.
BG damage prevents learning to avoid dark arms and enter lighted arms, a perceptual-motor skill.
Such research may generalize to humans.
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Learning Deficits after Lesions
• Study findings show that BG is critical in learning that involves generating motor responses based on environmental cues.
A. Normal B. Cues with Lights
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Neural Activity during Perceptual-Motor Skill Learning
• Rats’ BG activity recorded electrically before and during T-maze learning. As training progresses, BG neurons begin firing
mainly at beginning and end of each trial; eventually encompass 90 percent of firing.
• BG may develop a motor plan consistent with Fitts’ skills learning model i.e., automatic motor control eventually replaces
active control.
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Changes in BG Firing Patterns during Skill Learning
Adapted from Jog et al., 1999.
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Brain Activity during Cognitive Skill Learning
• Probabilistic classification (weather prediction task): Participants must learn to predict “rain or sun”
based on patterned cards.
Trial-and-error cognitive skill improved with practice.
fMRI images showed BG activation and hippocampal deactivation.
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The Weather Prediction Task:Do you think there will be rain or sun?
• Trial and error
• Pressed a switch for “rain.”
• Correct answer flashed after each trial.
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Neuroimaging during Weather Prediction Task
(b) Adapted from Poldrack et al., 2001.
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Brain Activity during Cognitive Skill Learning
• BG may enable skill learning, but specific role is unclear.
• Activation may reflect sensory cortical changes going into the BG.
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Cortical Representation of Skills
• Mammals are highly trainable and use cerebral cortex extensively.
• Neuroimages show cortical regions involved in skill performance expand with extensive practice. Specific somatosensory cortex expansion in
professional violinists.
Jugglers showed 3 percent increase in gray matter of visual cortex area that responds to motion.
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Are Skill Memories Stored in the Cortex?
• Participants learned a finger movement skill. Power law performance pattern corresponded
with motor cortex activation.
Regional motor cortex activation expanded with later practice.
Similar pattern in rats.
• Need further research in cortical and BG interactions during variety of skill learning.
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Changes in Skill Performance and Associated Motor Cortex during Training
(a)Adapted from Karni et al., 1998. (b) Images © 1998 National Academy of Sciences, U.S.A
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Learning and Memory in Everyday Life—
Are Video Games Good for the Brain?
• Video game-playing proficiency requires perceptual-motor and cognitive skill development.
• College students who played high-action video games (at least 4 days a week for at least 6 months) increased visual attention abilities compared with a control group.
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Learning and Memory in Everyday Life—
Are Video Games Good for the Brain?
• Such skills MAY be transferable to other visual-motor abilities.
• Further research is needed on advantages and disadvantages of video game playing.
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The Cerebellum and Timing
• Animals with little cortex (pigeons, fish) learn mazes or lever pressing.
• Cerebellum is important in encoding and retrieving skill memories. Has inputs from spinal cord, sensory systems and
cerebral cortex.
Has outputs to spinal cord and cortical motor systems.
Important in learning precisely timed movement sequences (acrobatics, dancing).
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The Cerebellum and Timing
• Rats that learned complicated motor tasks developed more cerebellar synapses. Compared to rats running an exercise wheel.
• Mirror tracing—copying a figure using a mirror image of the figure and one’s hand Involves tracking a target
Patients with cerebellar damage have poorer performance, but equivalent learning rate, of a control group.
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The Mirror Tracing Task
Adapted from Laforce and Doyon, 2001.
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4.2 Interim Summary
• Brain areas in skill learning: Basal ganglia (BG)
Link sensory events to responses.
Cerebral cortexMainly involved in controlling complex actions.
CerebellumNecessary for perceptual-motor skill performance; critical for movement sequences with precise timing (e.g., dance) and tasks that involve target tracking.
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4.2 Interim Summary
• BG output signals are sent to: Thalamus
Affects interactions between thalamic and cortical neurons.
Brainstem Influences signals sent to spinal cord.
• Results of maze learning studies with BG damaged rats suggest BG is critical for motor response learning with environmental cues.
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4.2 Interim Summary
• BG neural response patterns change during motor skill learning. Representations of skill are dynamically modified as
learning proceeds.
BG also active during cognitive skill learning.
• Regions of somatosensory and motor cortexes needed to perform a particular skill expand with practice. Less-relevant regions show little or no change.
4.3
Clinical Perspectives
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4.3 Clinical Perspectives
• Apraxia
• Huntington’s Disease
• Parkinson’s Disease
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Apraxia
• Apraxia—poor coordination of purposeful, skilled movements; most commonly from head trauma or stroke Left parietal damage causes difficulty imitating
actions.
With frontal damage, cannot pantomime actions with two hands.
Cortical damage hinders control and execution of skills.
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Apraxia
• Using transcranial magnetic stimulation (TMS), researchers can simulate conditions like apraxia.
• Therapy includes behavioral training with extensive repetitive practice.
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Using TMS to Modulate Cortical Activity
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Huntington’s Disease
• Huntington’s disease—inherited; causes damage to brain neurons (especially in BG and cerebral cortex)
• Results in: Psychological problems (mood disorders,
hypersexuality, psychosis).
Slow loss of motor abilities.
Early facial twitching and progressive shaking of body parts.
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Huntington’s Disease
• http://www.youtube.com/watch?v=tzBiqT947kM
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Huntington’s Disease
• Huntington’s disease—inherited; causes damage to brain neurons (especially in BG and cerebral cortex)
• Results in: Psychological problems (mood disorders,
hypersexuality, psychosis).
Slow loss of motor abilities.
Early facial twitching and progressive shaking of body parts.
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Huntington’s Disease
• Can slowly learn new skills; but difficulty with mirror reading and weather prediction tasks.
• Can learn some cognitive tasks, such as Tower of Hanoi puzzle.
• Perceptual-motor skills also hindered by movement impairments (to an undetermined degree).
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Huntington’s Disease and Impaired Skill Learning
Adapted from Knowlton et al., 1996.
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Parkinson’s Disease
• Parkinson’s disease—increasing muscular rigidity, tremors, difficulty initiating movements Reduction in brainstem neurons that modulate BG
and cerebral cortex activity
Decreased dopamine
Difficulty learning serial reaction time and rotary pursuit tasks
Can learn mirror reading
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Parkinson’s Disease
• Drug therapies and surgical procedures may temporarily relieve symptoms (e.g., deep brain stimulation to BG-cortical loop).
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Parkinson’s Disease
• Parkinson’s disease—increasing muscular rigidity, tremors, difficulty initiating movements Reduction in brainstem neurons that modulate BG
and cerebral cortex activity
Decreased dopamine
Difficulty learning serial reaction time and rotary pursuit tasks
Can learn mirror reading
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Parkinson’s Disease
• http://www.youtube.com/watch?v=tBRzBQ1Rlb0
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4.3 Interim Summary
• Apraxia: Results from cortical region damage (often from head
injury or stroke).
Patients have difficulty producing purposeful movements.
Damage interferes with skill control and execution more than with skill learning and recall.
With transcranial magnetic stimulation, researchers simulate apraxia and study effects of cortical disruption on skill memory.
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4.3 Interim Summary
• Huntington’s disease: Inherited disorder
Causes gradual damage to neurons throughout brain (especially in BG and cerebral cortex).
Patients show deficits in perceptual-motor skill learning.Related to problems with retrieval and decreased storage capacity.
Some progress in identification through genetic markers but prevention and treatment still in early research stages.
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4.3 Interim Summary
• Parkinson’s disease: Involves disruptions in normal BG functioning and
progressive deterioration of motor control.
Patients show increasing degrees of muscle tremors and rigidity.
Deep brain stimulation (delivers an electrical current to the basal ganglia–cortical loop) may offer treatment possibilities.