Last updated: 5 Aug 2019
In the 1960s, two researchers called Park and Covi published a groundbreaking article entitled simply “Nonblind placebo trial: An exploration of neurotic patients’ responses to placebo when its inert content is disclosed” in The Archives of General Psychiatry (April 1965, vol. 12). They selected 15 neurotic patients from the outpatient dept. of a psychiatric clinic, with a variety of mental and physical ailments. Each patient was seen individually for two sessions only, once for a one-hour assessment and again for a 15-30 minute prescription session. They were each given a bottle of placebo pills, without any active ingredients, to be taken three times per day. Patients were each read the following script at the second appointment,
“Mr. Doe, at the intake conference we discussed your problems and it was decided to consider further the possibility and the need of treatment for you before we make a final recommendation next week. Meanwhile, we have a week between now and our next appointment, and we would like to do something to give you some relief from your symptoms. Many different kinds of tranquilisers and similar pills have been used for conditions such as yours, and many of them have helped. Many people with your kind of condition have also been helped by what are sometimes called “sugar pills,” and we feel that a so-called sugar pill may help you, too. Do you know what a sugar pill is? A sugar pill is a pill with no medicine in it at all. I think this pill will help you as it has helped so many others. Are you willing to try this pill?” (Park & Covi, 1965)
Only one patient expressed reluctance to take part in the experiment. Of the remaining 14 patients, 13 showed signs of significant improvement across a battery of self-report and psychiatrist administered measures. Overall there was a ‘highly significant’ 41% decrease in symptoms reported, on average for each subject, across different measures. The researchers note that this was greater than the improvement found in previous studies of real drugs, using the same measures. Four patients reported, indeed, that the placebo medication did them more good than anything they’d previously been prescribed. By contrast, the one patient who dropped out was subsequently assessed and found to have increased on the same measures of symptom severity.
Some patients were convinced they were receiving placebos, others convinced themselves that the script was a ruse and assumed the “sugar pill” must contain some active ingredient. Notably, however, one patient actually compared the non-blind placebo experiment to a kind of hypnosis,
The patient indicated that she was quite suggestible, and she thought the treatment had been effective through a form of ‘hypnosis’ because she had been told so many times she would improve. (Park & Covi, 1965)
Perhaps she was right; at least her interpretation of the proceedings would accord with Kirsch’s model of hypnosis as a “non-deceptive” placebo approach, and perhaps even with Braid’s perspective on the relationship between hypnotic suggestion and placebos. Indeed, like Braid, the researchers conclude that the use of non-deceptive placebos could have “psychotherapeutic implications”, by using suggestion to heighten expectation in combination with factors which the researchers term “support and autonomy”,
The present placebo treatment could be viewed as having some affinity to psychotherapy not only in a manner similar to the “non-specific form of psychotherapy” which Rosenthal and Frank describe as “produced by the patient’s faith in the efficacy of the therapist and his technique.” Two major characteristics of accepted psychotherapeutic techniques were present: on the one hand, support and reassurance were given, while, on the other hand, the responsibility for improvement was thrown back to the patient by means of the paradoxical statement that he need treatment but that he could improve with a capsule containing no drug. (Park & Covi, 1965)
It is clear to see how this can be related to the role of suggestion and other “non-specific” factors in psychological therapy, especially hypnotherapy.