Question

Meditation for anxiety An experiment that claimed to show that meditation lowers anxiety proceeded as follows. The experimenter interviewed the subjects and rated their level of anxiety. Then the subjects were randomly assigned to two groups. The experimenter taught one group how to meditate and they meditated daily for a month. The other group was simply told to relax more. At the end of the month, the experimenter interviewed all the subjects again and rated their anxiety level. The meditation group now had less anxiety. Psychologists said that the results were suspect because the ratings were not blind. Explain what this means and how lack of blindness could affect the reported results.

Short answer

The lack of blinding may bias the reported results because the results may be influenced by the placebo effect.

Step-by-step solution

Given information

We need to find why Psychologists said that the results were suspect because the ratings were not blind .

Simplify

In a double-blind experiment, neither the subjects nor the people who measure them know which treatment they had, whereas in a single-blind experiment, either the people who measure or the people who get the results know which treatment they got (but not both).
The placebo effect is an effect created by a placebo that cannot be attributed to the placebo itself and must instead be attributed to the patient's belief in the treatment.

The subjects understand which therapy they underwent, and the psychologists know which treatment was provided to which participants (since they are the ones who measure the results), so the study was not blinded in any way.
The lack of blinding may bias the reported results because the results may be influenced by the placebo effect, and there is no group that received a placebo to compare with, therefore the placebo effect cannot be taken into account.
As a result, the patients' belief in the treatment may have an impact on the results.