ANSWER TO "TRUE DOUBLE BLIND STUDY" ISSUE

Polyg06nov      

  There is a logical answer to this question which is one that even lay people ask about pharmacological applications, but which psychologists and psychophysiologists fail to ask about purported applications of psychophysiology like biofeedback and the polygraph.

     Ron Heslegrave and I wrote a rather technical account of the reason why the “specific effects” logic needs to be applied to the polygraph (and biofeedback) as it is applied to pharmacology (http://www.psych.utoronto.ca/~furedy/Papers/ld/some_elab.doc), but let me try to summarize this argument here in more lay terms.

     First, the pharmacological example.  The claim for aspirin is that it reduces headaches.  The appropriate double-blind study is to contrast an aspirin with a placebo condition, where neither the subject nor the experimenter knows what condition the subject is in.  If the aspirin condition contains fewer and less severe headaches than the placebo condition (as has been found), then we can conclude that aspirin has a specific beneficial effect on headaches although we still don’t know the mechanisms through which aspirin produces this specific effect (it turns out that after many years of research, we still don’t know exactly how aspirin works).

            The claim for biofeedback is that the provision of precise psychophysiological information about some physiological function not subject to voluntary control to the subject (e.g., second-by-second information about heart rate changes) will, in itself, produce an improvement in the subject’s ability to control those changes (e.g., producing heart-rate deceleration).  Usually biofeedback’s specific beneficial effects are medically relevant (e.g., decreasing blood pressure).  Therefore the double-blind evaluation of whether biofeedback does have such a specific (beneficial) effects is to a completely accurate information condition with one where the information is less than completely accurate (if it’s obviously inaccurate then the subject is no longer “blind”, and an improvement may be due to a placebo effect, i.e., the belief that biofeedback is beneficial).  Such a study has not only not been done in the clinic (where it may be difficult to do), it has not even been done in the lab with the outcome that shows that biofeedback is beneficial.  This, as I have argued (Furedy, J.J. (1987).  On some research-community contributions to the myth and symbol of biofeedback.  International Journal of Psychophysiology, 4, 293-7.), is a serious methodological failing of the psychophysiological research community.  Moreover, Diane Riley and I published an earlier study where we did use this proper reduced-accuracy-of-feedback control, and found no beneficial effect of biofeedback on the ability to produce heart-rate decelerations, although subjects did learn, through instructions to improve this ability  (Riley, D.M., and Furedy, J.J. (1981).  Effects of instructions and contingency of reinforcement on the operant conditioning of human phasic heart rate change.  Psychophysiology, 18, 75-81).  But that is simply the same as the old country doctor telling an older male not to have arguments with his wife, and therefore avoid accelerating his ailing heart.  For this instructional advice, no biofeedback or the software for expensive psychophysiological equipment for measuring second-by-second change in heart rate are necessary.  Rather, this equipment is placebo paraphanalea for peddling biofeedback as the shake oil of the 21st century.

                 Despite being called a “test”, the CQT polygraph is not a specifiable procedure like the giving of aspirin or the provision of precise psychophysiological information, but for the purpose of applying the logic of the double-blind evaluation (which is a necessary condition for establishing the benefits of any treatment), let’s assume that it is a test, especially as, in the laboratory version, it is more specifiable and standardizable than in the field version.  Granting this test-status assumption, the purported benefit of the polygraph is that, by providing precise psychophysiological information to the experimenter or examiner, the accuracy of the examiner or experimenter (i.e., in differentiating truthful and deceptive subjects, or innocent and guilty subjects) is enhanced.  The appropriate double-blind control in the lab, therefore, is to provide examiners in one condition with precise and completely accurate information about the examinee’s autonomic responses to various questions, while in the other condition, there the psychophysiological information is less accurate, but not so inaccurate that the examiner can tell which condition he is in.  While this may be a difficult study to conduct in the field, it is easy, in principle, to conduct in the lab.  Then, if the psychophysiological information is more than a mere interrogatory prop, the examiner under the completely accurate condition should be better at detecting deception or guilt than the examiner under the degraded accuracy condition.  Such a study, to my knowledge, has never been performed, or a least published in the refereed journal literature even in the lab, let alone the field.


All the best, John