How “Blind” Are Double-Blind Placebo-Controlled Trials of Benzodiazepine Hypnotics?

Perceived treatment, feedback, and placebo effects in double-blind RCTs: an experimental analysis

“…To the extent that the positive feedback used here is analogous to the improvement that participants may experience during a double-blind RCT, then these experiments clearly demonstrate that observable improvement leads participants to believe they are on active treatment more frequently than when they observe a lack of improvement. While this is consistent with correlational evidence that improvement is related to perceived treatment (e.g., Margraf et al 1991;Morin et al 1995), this is the first study to show experimentally that observable improvement does influence perceived treatment. Furthermore, the experiments showed that participants who believed they received active treatment demonstrated better cognitive performance than those who believed they received the placebo.…”

Effects of oral temazepam on sleep spindles during non-rapid eye movement sleep: A high-density EEG investigation

“…Second, the temazepam night was part of an open-label extension, and thus our unblinded design may have affected results. However, prior studies utilizing temazepam have demonstrated that even in double-blind protocols, study participants are usually able to discern whether they are on active drug or placebo (Morin et al, 1995), which reduces the likelihood that our results would have differed using a blinded protocol. Third, there may have been an order effect as TMZ nights occurred after PLC nights.…”

A Randomized Clinical Trial Comparing Chiropractic Adjustments to Muscle Relaxants for Subacute Low Back Pain

“…It would seem that the blinding procedures used here were no less successful than those used in other rigorous randomized clinical trials. 56,57,64 Blinded, randomized clinical trials are considered the gold standard of experimental design. 9,15,21,65 Yet, blinding remains elusive in studies where the intervention may be invasive (eg, surgery, acupuncture) or involve physical contact between the subject and the care provider (eg, chiropractic, osteopathy, massage).…”