week 9 Flashcards
microgravity
condition wherein the force of gravity is very small
- forces acting on body is 0
- challenging to study motor control
most well known microgravity environment
is on the international space station
- task become more complex due to variety of factors
what tasks become more difficult in mircogravity
- changes in physioloigical systems
- changes in sensory consequences about learned action
parabolic flights
offer an environment for which to study the effects of mircogravity
- at the peak of the trajectory the gravitational force is close to 0
Einstein’s equivalence principle
- no measuring devices (and by extension no sensors in the body) can distinguish between inertial and gravitational forces
astronauts and cosmonauts must take time to set up experiments once in orbit
adaptive to microgravity is occurring during this time
prolonged physiological changes may affect the results
there is not hydrostatic pressure
- redistribution of bodily fluids
experiments in parabolic flights
can achieve microgravity within seconds
- last (20-30s)
- need more flights to get adequate data collection time
- can have a variety of participants
- aircraft can rotate and conditions may nit be as stable
what did early work in microgravity focus on?
vestibular-ocular reflexes (VOR)
vestibular-ocular reflexes (VOR)- in microgravity
- when head rotation is sensed the eye begin to rotate in the opposite direction
why does eye begin to rotate in the opposite direction
eye velocity is matched to the head velocity (but in oppoistie direction)
vestibular-ocular reflexes (VOR)- when the limit of eye motion is reached
- the eyes make rapid adjustment to bring gase to the new location
nystagmus
are eye movements that occur to adjust to prolonged fixation
- alternate fast and slow phases
- if heads keeps moving
how does nystagmus stop?
if head keeps moving (at near constant velocities)
when do nystagmus continue
is head rotation stop abruptly
- endolymph continues to move
what do the otolith (utricle and saccule) organs sense
linear accelerations
- are unloaded in mircogravity
what do the semicircular canals sense?
head rotations
- these are unaffected by microgravity
Coriolis cross-coupled stimulation
an unusual combination of linear and angular accelerations
- elicited by tilting the head while in a rotating chair
- severe disorientation and nasuae on earth
skylab M-131 investigating coriolis cross-coupled stimulation
no disorientation or nausea
- could not determine whether this was an adaption
- eye movements were not measured
velocity decay
- after a quick head movement, our vestibular ocular reflex works to move our eyes to stabilize our vision
what is velocity decay the measure of
the reduction in eye-movement velocity in the slow phase after the initial response
VOR during parabolic flight (DiZio and Lackner 1991)
velocity decay occured throughout
- indicated that velocity storage phenomenon is affect by microgravity
decay is steeper in ____ compared to _____
- microgravity
- normo-gravity
what can alos be affected by mircogravity
proprioception
proprioception and mircogravity
- Limb- matching experiments show decreased ability to compensate for vibration induced noise
- body position is less accurate
origin of proprioceptive deficits
some studies suggest the lack of vestibular inputs could impact integration stragies employed by the brain
- lack of gravity leads to less activation of muscle sense
proprioception and loading
the idea that the absence of gravity may affect proprioception supports one of the original assertions about kinesthesia
what is proprioception on earth related to?
loading
what could we do in the 0G environment to reduce errors
we would load
- replicate the load using a form of resistance
Bringoux et al, 2012
used resistance to get more accurate matching
- adding external load made it more similiar to the 0G environment
results of Bringoux et al, 2012
- the addition of a gravity-like torque made joint-position sense more similar to 1G environment in a midsagittal reaching taks in 0G
what does Bringoux et al, 2012 support
the idea that proprioception during movement planning and control is tuned to the gravitational environemnt
how does microgravity affect online arm movement corrections?
- limb-position sense is altered in microgravity
double-step or target jump paradigm
is a commonly used method
- participants performs reaches to a target location and on some % of the trials the target “jumps” or “steps”
bringouz et al, 2020
- very little differences in endpoint error or limb-kinematics between 0g and normal gravity conditions
- inverse dymnamics analyses revealed that the muscular torques required to generate correction were significantly different in normal and mirco
bringouz et al, 2020 final results
taken together these results highlight that the central nervous system can flexibly adapt control processes to gravitational constraints
how does the NS adapt to microgravity
in environments where some sensory information is compromised we might weigh other sources of sensory information more
forms of sensory information
visual information
auditory information
visual information
spatial localization
auditory information
timing
measuring sensory weighting
electroencephalography (EEG)
electroencephalography (EEG)
can be used to measure the brain response to sensory stimulation
- measuring the brain response to stimulation is known as evoked potential
evoked potential and sensory integration
- are modulated by attention to stimulus
- also been used in motor control research
evoked potential in research
- somatosensory information processing is reduced during mirror-reversed drawing
- visual evoked potentials increased when visual information is used to plan control goal-directed movements
what is sensory re-weighting in Microgravity
- when preparing a stepping movement, proprioceptive signals from ankles are important for maintaining balance (increased somatosensroy stimulation)
proprioceptive signals are less important for movement control in microgravity
decreased response to somatosensory inputs in microgravity as compared to norm gravity
saradjian results
- participants exhibited an increased late somatosensory evoked potential when preparing a step in norm gravity
- in the absence of postural constraints in mirco, no facilitation’s of somatosensory info was found
- sugges the NS can dynamically adjust the weighting of sensory information to gravitational constraints
is vestibular and proprioceptive feedback altered in microgravity
yes, but CNS adapts sensory feedback to overcome the environmental constraints
stable differences in between-individual performance
- between-person variability
- exacerbated in patient populations
- related to abilities
abilities
stable traits that underlie/support persons skill
- genetic component
- maybe not completely trainable
when did study of individual different start
post world war II for pilot selection
- needed to select trainees rapidly for training in military
what did fleishman argue?
that we could predict motor skill learning from difference in abilities
- most important predictor for skill acquisition is the number of hours of practice
predictor of motor ability - Fleishman
- used alot of tests to determine if transfer can be predicted performance on simple motor tasts
predictor of motor ability - Fleishman results
found that bimanual coordination and reaction time predicted transfer performance
fleishman and ellison 1969 results
- found that some motor still tests correlated with the amount of the transfer
- they concluded that the ability of these participants facilitated learning
- individual difference in perceptual-motor ability may predict learning
early studies issues
- was to develop motor aptitude test
noble undertaking
to determine how individual respond to practice
- design better environments and promote learning
motor aptitude test- in practice
lead to exclusion of individuals who do not posses the right aptitudes
- these individuals are often labelled with low-motor ability
early studies relationships
are largely correlational rather than interventional
- did not control for prior exposure or practice
nature and nurture debate
nature: athletes are born not made, relates performance to abilities
nurture: athletes are made not born, relates performance to skill, its all about practice
individual difference research
- difference in initial performance
- differences in the rate of skill acquisition
- differences in maximum skill levels
difference in task performance with exception of a new born
- when an individual encounter a new task there is always some degree of transfer involved
transfer can be
positive or negative
positive transfer
experience helps the learner perform the new skill
negative transfer
experience may hamper the performance of the new skill
better learner may have abilities and skills that _____ to a new task
positively transfers
when looking at learning paradigms we use what
pre-post design
pre-post design
performance prior to acquisition is compared to performance in retention and transfer
difference score equation
RMSE post- RMSE pre= difference score
what performers will show the greatest difference?
performance with the lowest initial performance
wechsler 1952
differnece between the best and worst performers was 3:1
- best peformers is 3x the amount of productivity as the nest best performers
maximin skills levels- difficult to determine if this is related to abilities
- both transfer effect and initial skill level change will progressing through practice
what were early theories on individual difference based on
measurements
fleishman and hempel 1954, 1955 argued
intellectual and cognitive ability facilitated early performance and acquisitions of motor skills
- later performance was based on task-specific abilities
limitation’s of fleishman and hempel 1954, 1955
- general ability is only important for the initial leaning of a skill
- performance can only be predicted after practice
individual difference how research is driven
- people do not have equivalent abilities, personalities and motivational traits
how can task be varied
- pocessing demands can change over repetition
- task become easier to perform
- tasks can also continue to be difficult
what is the three phase theory of individual differences
- that individal differnces prior to practice could affect learning
phase 1 of the three phase theory
Ackerman and Kyllonen 1991
initial learning stage
- strong attentional and cognitive demands
- general intelligence
most important general intelligence
spatial, verbal, numberical
phase 2
integration and consolidation
- attentional demands are streamlined
- perceptual speed abilities (the rapid encoding of movement patterns)
- comparison and contrast abilties (comparing 2 numbers)
- perceptual - involves aspects of human information processing
what are phase 2 abilities thought to be assoicated with
ability to chain responses
phase 3
skilled performance becomes more proceduralized (automatic)
- more movement fluidity is achieved and attentional demands demands are reduced
what is phase 3 dependent on
psychomotor abilities
- related to motor competnece of individual
summary of the 3 phases
- figural, verbal, numerical
- perceptual speed
- psychomotor
the skill acquisitions stages of the 3 phases
- cognitive phase
- associative phase
- autonomous phase
what do more studies support
declining relationship between cognitive ability and motor capability
Ackerman and cianciolo 1999
only group of studies systematically looking at the predictive validity of perceptual and psychomotor skills
- findings based on correlations
what was acherman and cianciolo 1999
- combinations of perceptual-speed tests (simple RT tests) and psychomotor tests (Choice RT tests) were correlated with performance
focus on ___, not ___
practice
abilities
what is the lack of research and development into individual difference is partly due to?
deliberate practice
- the idea that practice conditions can be optimized to facilitate the attainment of expertise
focus on practice not abilities and how can we help learners reach their goals
- optimize practice conditions
- shifted the debate back to nurture and optimizing conditions
recommendations to overcome individual differences
- invest in everyone
- more grassroots focus, greater pool of playerss, more likely to generate an environment that fosters motor skill acquisition’s
- achieves larger goal of promoting physical acitivty
what is the overall idea to overcome individual differences
focusing on practice conditions may overcome initial difference in abilities
