Chapter 4 – Skill Memory
A Skill is ability that an individual can improce over time through practice. Skills
that depend on performing predefined movements that, ideally, never cay are
called closed skills. Open skills are those that require performing movements in
response to predictions about ongoing changes in circumstances.
Practice can decrease the effects of previous experience on motor performance
and increase the effects of genetic influences. Feedback about performance, or
knowledge of results, is critical to the effectiveness of practice.
The power law of earning states that with extended practice, the amount of time
required to complete a task decreases at a diminishing rate. This “law of
diminishing returns” holds for a wide range of cognitive and perceptual-motor
Massed practice, or concentrated, continuous ractice, generally produces better
performance in the short term, but practice that is spaced out over several sessions
leads to better skill retention in the long run. Similarly, constant practice, which
means repetition of the skill under fixed conditions, does not improve
performance as much as variable practice, practicing the skill in carrying contexts.
Implicit learning, which is the learning o skills without an awareness of learning,
is often tested with the serial reaction time task. Implicit learning is also studied in
patients with amnesia.
Thorndike’s identical elements theory proposes that the degree to which learned
abilities are transferred to novel situations depends on the number of elements that
are identical between the learning context and the novel situation. When an
individual no longer uses a learned skills, it is lost in a process called skill decay.
Changes in skill memories produced by extended practice may occur in stagesL
the cognitive stage, when the skill is encoded through active thinking; the
associative stage, when the skill is performed using stereotyped actions; and the
autonomous stage, when the skill has become a motor program.
Skill learning depends on three brain areas: the basal ganglia, the cerebral corte,
and the cerebellum. Output signals from the basal ganglia are sent mainly to the
thalamus (affecting interactions between thalamic and cortical neurons) and to the
brainstem (influencing signals sent to the spinal cord).
Studies of how rats with basal ganglia damage learn to navigate mazes suggest
that the basal ganglia are critical for learning to generate motor responses based
on environmental cues
Neural response patterns in the basal ganglia change during the learning of a
perceptual-motor skill, suggesting that representations of that skill are
dynamically modified as learning proceeds. The basal ganglia are also activated
when people learn cognitive skills such as the weather prediction task.
Regions of the somatosensory cortex and motor cortex needed to perform a
particular skill expand with practice, but regions that are less relevant show fewer,
if any, changes.
An intact cerebellum is necessary for performing many perceptual-motor skills.
The cerebellum is especially critical for learning movement sequences that require precise timing, such as dancing, and tasks that involve aiming at or tracking a
Whereas the cerebellum is critical for timing, the cerebral cortex is mainly
involved in controlling complex actions, and the basal gangia link sensory events
Apraxia results from damage to cortical regions, most commonly from a head
injury or stroke. Patients with apraxia have difficulty producing purposeful
Skill learning by patients with apraxia suggests that the damage interferes with
control and execution of skills more than with the learning and recall of skills.
Transcranial magnetic stimulation allows researchers to stimulate apraxia in
healthy volunteers and study the effects of cortical disruption on skill memory.
Huntington’s disease is an inherited disorder that causes gradual damage to
neurons throughout the brain, but especially in the basal ganglia and the cerebral
cortex. Patients with Huntington’s typically show large deficits in perceptual-
motor skill learning that seem to be related to problems with retrieval and
decreased storage capacity, Scientists have made progress identifying
Huntington’s through genetic markers, but prevention and treatment of deficits
are still in the early stages of research.
Parkinson’s disease involves both disruptions in the normal functioning of the
basal ganglia and progressive deterioration of motor control. Patients with
Parkinson’s show increasing degrees of muscle tremors and rigidity. Deep brain
stimulation, which delivers an electrical current to the basal- ganglia-cortical loop,
may offer treatment possibilities.
Qualities of Skill Memories
Skill memory consists of what a person knows how to do. A skill is an ability that
you can improve over time through practice. Skill memories are long-lasting and
improved by repeated experiences. Skill memories cant always be verbalized; may be
acquired and retrieved without conscious awareness. Psychologists sometimes classify
skill memories as nondeclaritive memories, because these memories are not easily put
into words. Skill memories classified into two general types: perceptual-motor skills and
Perceptual-Motor skills are learned movement patterns guided by sensory
Psychologists classify skills such as dancing, which consist of performing
predefined movements as closed skills.Researchers classify skills that require
participants to respond based on predictions about the changing demands of the
environment as open skills.
Most perceptual-motor skills contain aspects of both closed skills and open skills.
Skills lie somewhere on a continuum from open to closed. Cognitive Skills
Cognitive Skill: a skill that requires problem solving or the application of
strategies. Researchers often conduct experiments on cognitive skills that participants can
learn relatively quickly, such as those used to solve simple puzzles like the Tower of
Hanoi. Normally, people get better at this puzzle with practice. This is not because they
are getting better at moving disks from one peg to another (a perceptual-motor skill), but
because they are learning new strategies for moving the disks so that they end up in the
Tool use is an ability that typically involves both perceptual-motor and cognitive
Expertise and Talent
Talent: a person’s genetically endowed ability to perform a skill better than most.
Expert: a person who performs a skill better than most.
Rotary Pursuit Task: an experimental task that requires individuals to keep the
end of a pointed stick (stylus) above a fixed point on a rotating disk; used to study
perceptual-motor skill learning.
Researchers found that when they trained twins to perform the rotary pursuit task,
identical twins’ abilities to keep the stylus on the target became more similar as training
progressed, whereas fraternal twins’ abilities became more dissimilar.
One of the interpretations of these data is that, during the experiment, practice
decreases the effects of participants’ prior experiences on the accuracy of their tracking
movements and increases the effects of genetic influences.
Some psychologists argue that innate talent plays no role in expertise and that
practice alone determines who will become an expert. Scientists investigating skill
memory in experts suggest that practice is critical in determining how well a person can
perform a particular skill.
Researchers studying expert chess players found that experts and less experienced
players scan the game board (a visual-motor skill) differently.
If skill is an ability that improves with practice, chess-playing computers can be
considered experts without skills, unless they are programmed to improve their
performance based on past experiences.
Knowledge of results: feedback about performance of a skill; critical to the
effectiveness of practice.
With extended practice, the