[From Bruce Abbott (981022.1405 EST)]
Chris Cherpas (981022.1111 PT) --
Have you considered a continuously varying
quantity which is correlated with the amount
of time to food delivery, in other words,
a "clock?" My first take on it would be to
use a conjunctive schedule in which the clock
progresses towards the dinner bell as long
as the rat keeps some quantity within some
upper and lower bounds around a target
value, and in fact, it could continuously
vary with distance to the target value, but
I imagine you will need some layers of
contingencies working conjunctively that
use upper/lower bounds, a continuous
gradient (maybe not arithmetic/interval
scale), a set of graduated patterns of
disturbances that the program can switch
between, with parameters around the
time-to-food interval, the upper/lower
tolerances, and so forth.
(I'm sure most readers' response to this was "huh?" Fortunately (or
unfortunately) for me I speak Skinnerian -- or is it CherpasSpeak? SKED?
Oh well, whatever, I get your drift.
_Something_ like that had occurred to me but I'm not quite sure how to adapt
it to rats. With pigeons the length of a line projected on the key seems to
work well, but rats don't see all that well and I'm not sure they would
attend to something like a varying tone frequency or light intensity in the
same way (although they probably could be trained to do so if one were
patient enough). This was what I had in mind with my suggestion to use the
tone as a correlated stimulus -- the program varies tone frequency (or
intensity) and the rat resonds to bring the parameter back to the range in
which food gets occasionally delivered independently of responding.
I should probably look into the literature on titrating schedules. If
memory serves, these arrange just the sort of contingency we're after, with
the program varying some parameter up or down and the rat responding to
bring the parameter back down (or up). Do you have any experience with
titrating schedules?
Regards,
Bruce