Participants needed some lifetime cannabis experience but had to be cannabis-oil naive. That combination was intended to make the labeling manipulation believable and limits generalization to experienced CBD-oil consumers.
Selection was part of the experiment
The study recruited healthy adults who had used cannabis at least once, reported use no more than twice weekly in the preceding month and had not used cannabis oil. Participants with specified medical or psychiatric conditions or most prescription medication use were excluded.
At the two experimental visits, participants received CBD-free hempseed oil under different descriptions: one said it contained CBD and the other said it did not. The intervention was information about the oil, not active CBD administration.
Prior familiarity could change expectations
Someone familiar with cannabis oil may evaluate its taste, sensation or claimed effects differently from an oil-naive participant. The selection rule reduced one potential challenge to the manipulation, but it did not establish that expectations operate identically in every consumer population.
Keep the result within its population
Selected subjective and physiological responses differed under the expectancy manipulation; overall stress and anxiety did not show systematic treatment-condition effects. The study does not show that every reported CBD benefit is expectation or that actual CBD cannot have pharmacological effects. Its selection criteria belong with its causal conclusion.
Related reading: defining stress-study outcomes.
Research cited
Spinella and colleagues (2021). Evaluating cannabidiol (CBD) expectancy effects on acute stress and anxiety in healthy adults: a randomized crossover study. DOI: 10.1007/s00213-021-05823-w.
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