[From Rick Marken (931109.0800)]
Martin Taylor (931108 19:40) --
You wouldn't see the feedforward in your tracking studies (much), because
the feedback does a good job. But try the sawtooth tracking studies with
irregular blanking of the target, and see what happens. Will the feedback
only models still account for 99% of the variance?
Now you're talking :an experiment! My guess is that we would need a
two level feedback control model to account for the results.
The model would always be closed loop -- although (like the subject)
it would be deprived of visual (not proprioceptive) perceptions
periodically. I bet we could develop a working feedback control
model of this situation that would work just as well as (probably
better than) a model that incorporated ad hoc rules about switching
to feedforward mode or whatever. I think this is actually an excellent
idea for an experiment. I think I'll try to set it up as a HyperCard
program (and model) this weekend. I think some advocate of feedforward
"control" should send me the equations and diagrams for the feedforward
alternative to the feedback model of this task.
Down with all-or-none thinking!
Down with thinking up explanations for behavioral phenomena (such as
feedforward "control") that either 1) don't exist or 2) are already
explained by PCT.
Best
Rick