Hi
On Wed, 11 Aug 1999, Rick Adams wrote:
> Stephen Black wrote:
> > Randomly assign subjects to either placebo therapy or cognitive
> > therapy. So far, we have single-blind (subjects don't know which is
> > the placebo). To make it double blind, have the outcome measures
> > taken by independent interviewers or observers who don't know which
> > treatment has been applied to which subjects. The interviewers would
> > have to be cautioned not to ask any questions which could reveal which
> > treatment the subjects had received, but this shouldn't be a problem.
> Except that, since the experimenters themselves would know if they were
> administering the placebo therapy or not, their interactions with the
> subjects could be compromised by the knowledge and the results skewed. :(
> In a medical double-blind experiment neither the subject _nor_ the
> administering physician know whether they are in the experimental group or
> the control group. That safeguard exists because doctors inadvertantly
> communicated which group the subject was in through their interactions
> (i.e., a doctor knowing a subject was receiving a placebo would
> demonstrate less concern for "side effects" than one who knew the subject
> was receiving the experimental substance).
Wouldn't this only be true of DRUG studies? Presumably doctors
performing operations know which one they are doing? I don't
think the problem of double-blind studies for many treatments is
unique to psychology.
In a parallel psychological
> experiment set up in the manner discussed above, the therapist would find
> it virtually impossible to avoid some degree of contamination of the
> experiment, if only through his/her lack of "authority" in the therapeutic
> system. Try using a non-existant form of therapy with a client and see how
> quickly the client begins to demonstrate lack of confidence in your
> capability as a therapist (a critical component in the therapeutic
> process). Thus, even if the observers were unaware of the nature of the
> therapy, a true double-blind protocol wouldn't exist.
But Steven and/or others mentioned that _plausible_ alternative
treatments can be developed. Another option that no one has
suggested yet is to computerize the different treatments. That
is, write computer therapy programs (sophisticated Elizas)
according to different therapeutic principles.
Best wishes
Jim
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James M. Clark (204) 786-9313
Department of Psychology (204) 774-4134 Fax
University of Winnipeg 4L02A
Winnipeg, Manitoba R3B 2E9 [EMAIL PROTECTED]
CANADA http://www.uwinnipeg.ca/~clark
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