[From Bill Powers (990404.1334 MDT)]
Bruce Abbott (990404.1335 EST)--
I wrote a long reply and trashed it. Arguing with you about these
experiments is just as pointless now as it was the first time I gave up
doing it. The experiments you describe are so poorly conceived, the data
taken so badly analyzed, and your conclusions derived by such mysterious
processes, that I despair of explaining to you what is wrong with them. If
you could understand any explanation I would give, you wouldn't have done
the experiments that way in the first place, or admired whoever did them.
I'll just give one example, the problem of measuring "rate of lever
pressing," a measure of a repetitive behavior. I thought you had understood
my original critique of the practice of using session averages for this
measure: total presses per session divided by session duration. If pressing
behavior were one simple kind of behavior that simply speeded up and slowed
down, a session average might (at a stretch) be a useful measure. But when
the animal's behavior changes _qualitatively_ during a session, so it
spends time away from the lever engaged in other activities, session
averages become completely invalid, giving true measures neither of
lever-pressing rates nor of any other actions that occur in the same session.
Suppose I am calibrating the swings of a clock pendulum. I start the
pendulum going and start an accurate reference timer simultaneously,
counting swings. After the 100th swing I record the timer reading in
seconds, compute the elapsed time, and divide the result by 100. This
calibrates the pendulum in terms of its period in seconds per swing, or if
I like I can calculate its frequency in swings per second.
Now I do the same thing with another pendulum, but this time I notice, just
after the 50th swing, that the pendulum is squeaking. So I stop it, go get
an oil-can, oil it, go put the oil-can away, return to the pendulum, and
start it up again, resuming the swing count at 51. Then, after the 100th
swing I read the timer as before and compute the period in seconds per swing.
Do you understand why the measure of the second pendulum's period is
invalid? And if that measure is invalid how can it be valid to use a
session average to measure bar-pressing rate when the rat spends part of
the session sleeping?
I thought we had reached agreement about this. But today, your post
indicates that you don't see why a session average doesn't give a true
measure of repetition rate. You haven't budged a millimeter.
Let's just drop the whole thing, Bruce. There are too many more problems
just like this, and you won't admit that any of them is a problem. Color me
fed up.
Best,
Bill P.