Final from Midterm 1 Flashcards
1
Q
motor program
A
- used to execute movement
- common language/ideas about organization/function of the motor system -> CNS, motor neurons, muscles and sensory organs
- movement = programmed action
- organized in advance, triggered to complete fully
- carried out without modification from feedback
2
Q
MP theory
closed- and open-loop
A
- closed-loop: long duration, slow movements
- open-loop: short duration, fast movements
- motor control is a complex blend of both closed-loop and open-loop processes
3
Q
evidence of MPs (5)
A
- studies of RT in humans
- experiments/case studied involving animals and humans in which feedback is removed
- studies of central pattern generators (CGP)
- impact on muscle activation when movement is unexpectedly blocked
- analysis of behaviours when humans attempt to stop or change an action
4
Q
evidence of MPs - studies of RT
A
- generally focused on limitations on stimulus identification and response selection stages
- limitations of the motor/response programming stage provides insight about MPs
- RT increases when: additional elements are added to an action, more limbs must be coordinates, or the duration of the movement becomes longer
- when influencing the complexity of the skill, the increases duration is attributed to the motor programming stage
5
Q
evidence of MPs - startled responses
A
- RTs can be dramatically shortened
- introducing a loud, unexpected acoustic signal usually produces typical startle indicators
- prepared movements produced normally, but with RT up to 100ms shorter
6
Q
Henry and Rogers experiment
motor skill complexity and RT
A
- increase in RT attributed to additional time required to program the more complex movement
- the number of movement parts + delay, movement accuracy effects, and movement duration all affect RT
- mean RT increased thru different stages
- complexity of response increased, more complicated movement pattern
- didn’t need to choose response, goal was selected for us
- motor programming is where the differences exist
7
Q
evidence of MPs - deafferentiation experiments
A
- severing (via surgery) an animal’s afferent nerve bundle where it enters the spinal cord, CNS no longer receives information from affected parts of the PNS
- sensory information from the moving limb is not absolutely critical for movement production
8
Q
central pattern generator (CPG)
A
- CPG: centrally located control mechanism that produces mainly simple genetically defined actions (eg. walking)
- in contrast, MP theory applies to learned skills (eg. riding a bike)
9
Q
evidence of MPs - inhibiting actions
A
- MP is released that:
- is responsible for initiation of an action
- serves to carry out the entire action unless a second stop signal program is initiated in time to arrest its completion
- stop signal paradigm is method most frequently used for studying action inhibition
- limb’s electrical muscle activity patterns unaffected for 100-120ms when limb is blocked by a mechanical interruption
- supports idea movement activities are organized in advance/run unmodified for 100-120ms
- point of no-return occurs at ~150-170ms before movement is initiated
- supports idea that MP is released and initiates entire movement unless second MP initiated before the 150-170ms range
10
Q
MP and the conceptual model
A
- MPs operate in motor system , sometimes in with feedback, to produce flexible skilled actions
- motor system concerned with ensuring intended action is generated + goal of movement (motor skill) is achieved
11
Q
major role of open-loop organization
A
- open-loop part of these actions provides the organization/instructions that feedback can modify:
- define and issue commands to musculature (eg. force, duration)
- organize the many degrees of freedom of the muscles and joints into a single unit
- specify and initiate preliminary postural adjustments necessary to support upcoming action (anticipation)
- modulate the many reflex pathways to ensure movement goal is achieved
- most effective in stable, predictable environments in which the need for modification of commands is low
12
Q
problems with MP theory
A
two major limitations of MP theory:
1. storage problem: how/where do we store the countless MPs needed for future use and how are they instantaneously retrievable?
2. novelty problem: how do performers produce truly novel movements if the MP isn’t already stored in memory?
- solution: a generalized motor program (GMP) who’s output can vary along certain dimensions to produce novelty and generalizability in movement
13
Q
generalized motor program (GMP) theory
A
- GMP underlies different classes of movements (eg. throwing, locomotion)
- structured in memory with a defined temporal organization
- variations in movement time (MT), and movement amplitude (A), and the limb used to represent the movement’s surface structure
14
Q
invariant features of a GMP
A
- GMP structure is characterized by its relative timing
- can be measured by a set of ratios among the durations of various events in the movement
- represents a movement’s deep, fundamental structure
- remains invariant, and its structure difficult to alter
15
Q
parameters added to the GMP
A
- relative timing may be carried out with the different surface features (eg. duration, amplitude)
- surface features are very easy to alter by parameter adjustment
- parameters change only how the GMP is expressed at any given time
16
Q
classes of actions - MPs
A
- MPs are thought to be generalized to account for a class of action (eg. throwing, kicking)
- parameters must be supplied to define the way in which the pattern is to be executed (eg. throwing with more or less velocity)
17
Q
speed-accuracy trade-offs
A
- slower skills are typically performed more accurately while faster are typically less accurate
18
Q
Schmidt’s Law
A
- describes why increasing the speed (decreasing MT) and/or distance (A) of a rapid movement task contributes to inaccuracy
- relative contraction forces of the various participating muscles are a major factor in determining trajectory of the limb, inconsistency (variability) in these forces increases with increased force
- more force is required to: move faster (decrease MT), and move further (A increases)
- more force generates more variability, which causes the movement to deviate from the intended trajectory, resulting in errors, measure by effective target width (We), similar to VE
= amplitude (distance)/movement time (time) = Distance/time = velocity
We = a +b(A/MT) - at very high levels of muscular contraction (>70%): reducing MT can decrease spatial and timing error, because of this increased accuracy, adding inertial load to the movement can decrease error up to a point
- an inverted-U relationship exists between spatial accuracy and force requirements, with least accuracy at moderate levels of force
19
Q
linear speed-accuracy trade-off
A
- vary the amplitude and movement time goal of the task
- described by Fitts’ Law
- closer target or slower MT = more accurate, further target or faster MT = less accurate
20
Q
effective target width (We)
A
- small We means they are more consistent, trials are focused in a small area
- medium We means more variability
- large We is the most variability, the trials are all over the place
- a measure of spatial accuracy
21
Q
movement amplitude and We
A
- We decreases as the movement amplitude decreases from 30cm to 10cm, because the participant becomes more accurate and consistent at a shorter distance from target
- more variability is seen with larger effective target width (We)
22
Q
movement time and We
A
- when we decrease MT from 200 to 140ms we see consistency and accuracy decreases
- as we ask people to move quicker, they become less accurate and consistent
23
Q
visual illusions
A
- aiming at targets can be influenced greatly by the immediate visual environment
- may not bean exception to speed-accuracy trade-offs because perceived target width does not predict observed outcomes, aiming errors were due to the participants perceptions of the targets
- could be an exception to Fitts’ law because the actual target dimensions do not predict the observed outcomes, we would expect that if the target looks easier they would perform better
24
Q
movement timing in skills with temporal goals
A
- skills with purely temporal goals seem to follow somewhat different principles than those having purely spatial goals
- decreasing MT has the effect of decreasing the timing error for skills with temporal goals, making movement more accurate in time, not less
- such as in sports like baseball where the batter has to time it perfectly to hit the ball, decreasing MT may give more time for perceptual judgements to occur
25
Q
initiating movement - the gunslinger effect
A
- when participants move first, they tend to do so more slowly than when reacting to an opponent (who had moved first)
- evidence from measures of peak velocity and time to reach peak velocity
- perhaps different neural mechanisms for self-initiated and reactive movements
26
Q
motor learning definition
A
- motor learning is a set of processes associated with practice or experience leading to relatively permanent gains in the capacity for skilled performance
- learning results from practice or experience, is not directly observables, and changes are inferred from certain performance changes
- practice: deliberate attempts to improve performance of a particular skill or action
- learning involves a set of processes in the CNS:
1. increased automaticity, together with speed and accuracy, in analyzing the environmental and movement feedback information (stimulus identification)
2. improvements in the ways actions are selected (response selection) and parameterized (movement programming)
3. building more effective GMPs and effector processes
4. providing more accurate and precise feedback
5. establishing more accurate references of correctness - learning produces an acquired capability for skilled performance
- learning changes are relatively permanent, not transitory
27
Q
performance curves
A
- plots of performance against practice trials
- whether they increase or decrease with practice depends on the way the task is scored
- the law of practice says that improvements are rapid at first and much slower later in practice
- rate of learning = steepness of curve
28
Q
limitations of performance curves
A
- performance curves are not learning curves
- between-subject effects are masked
- within-subject variability is masked
29
Q
retention tests
A
- testing participant on the same task after a time interval
- the longer the retention interval, the more performance is a true reflection of learning
- discrete tasks with relatively large cognitive components are forgotten relatively quickly compared to continuous tasks
30
Q
transfer tests
A
- involve new variations of the practices skill
- new speed or condition on practiced skill
- different task altogether
- allow sufficient time for the supposed temporary effects of practice to dissipate, the amount of time will vary depending on the nature of the temporary effects
- evaluate learners agains in a transfer or retention test, with all groups performing under identical conditions
- any differences observed in this transfer test are due to a difference in the relatively permanent capability for performance acquired during earlier practice
