[From Bruce Abbott (950606.1800 EST)]
Bill Powers (950605.1415 MDT) to Martin Taylor --
Your reply to Bill Leach's comment on choosing between unwanted
alternatives used an inappropriate example:
And given free control, I would drive straight from work to home,
if my control systems were not overwhelmed by the difficulty of
driving over kerbs and through houses that intervene. So I control
what I can, and arrive home by a more circuitous route.
Bill's comment was that _neither_ choice presented to the rats was one
it would select by itself. A more appropriate example would be, "Would
you rather be able to blow your car's horn or to have it silent while we
shove the car over a cliff with you in it?" Certainly you have a right
to study the effects of that choice if you want to, but it would be
pretty silly.
Perhaps I am reading too much into this, but your example suggests you
believe that all such questions (in which the participant is asked to choose
between alternatives, neither of which would be freely chosen) are ipso
facto "silly." I offer the following counterexample:
You want to know how well people will be able to continue to control a
cursor in a compensatory tracking task when visual input as to cursor
position is blocked. Your participants earn money so long as the cursor
remains within a certain narrow distance of the target. For the "blind
tracking" test you have them wear a blindfold, but you discover that two of
your subjects are cheating by peaking under the blindfold. What should you do?
You should:
(a) allow them to cheat because this is their preferred mode of
control over cursor position.
(b) prevent them from cheating, perhaps by taking steps to assure
that they will not be able to peak.
(c) abandon the research because you have determined that the
question is silly, as the nonvisual mode of control is not
the one the participants would select for themselves.
As for me, I'd shave their backs. (;->
Regards,
Bruce