feedback control Flashcards
why don’t trajectory control models work
can’t explain the flexiblity of human mvmt
doesn’t hold across all types of human behaviour (only when trajectory is the goal)
why does the optimal feedback control model work
able to account for how humans move
(minimising energy expenditure while minimising errors that jeopardise performance)
what is the downside of trajectory control
maintaining a specific hand path increases the variability of endpoints
what is the benefits/downside of optimal control
increased variability in hand path
maintains behavioural goal
what is the minimal intervention principle of optimal feedback control
correct only the deviations that jeopardise the outcome of the task
intervene only when needed to satisfy the task
what are the benefits of minimal intervention
reduces costly overcorrections (require the NS to spend unnecessary energy)
these corrections are wasteful and have the potential to introduce errors
(more muscles recruited = more variable mvmts)
when do we see goal directed responses in EMG
usually LLRs if background load is controlled
if background laod is not controlled (self activation of co contraction) = seen in SLRs and LLRs
when do goal directed muscle responses begin
emerges in LLR window
SLR responses are identical (dot v bar)
what are the differences in displacements based on perturbations in different target sizes
limit displacement when holding arm in smaller target size (lab 2)
how do EMG responses change as the size of target decreases (with a background load)
SLRs = same size - no goal related differences because of background load
LLRs = show goal related differences
what is the unimanual condition in the control of hand posture task
independent cursors and targets for each hand
perturbations applied to each hand individually
what is the bimanual condition in the control of hand posture task
one cursor represents the average position of both hands
common target (one goal)
perturbations applied to each hand individually
what correction is seen in both conditions when hands are hit away (out) from the target
unimanual = both hands correct back to individual goals
bimanual = very little correction seen (average position of cursor doesn’t change much when both hands hit away)
what correction is seen in both conditions when ONE hand is perturbed farther from the target
unimanual = both hands correct individually
bimanual = pick optimal path
- therefore correct with the lighter load hand and stop the heavier load hand
(less energy needed to correct the lighter load)
what correction is seen in bimanual condition when both hands are hit to the right of the target
both perturbed with the same force so they move back together
(response in bimanual condition depends on perturbation load)
