In marketing as in medicine, perception can be everything. A higher price can create the impression of higher value, just as a placebo pill can reduce pain.

Now researchers have combined the two effects. A $2.50 placebo, they have found, works better one that costs 10 cents.

The finding may explain the popularity of some high-cost drugs over cheaper alternatives, the authors conclude. It may also help account for patients’ reports that generic drugs are less effective than brand-name ones, though their active ingredients are identical.

The research is being published on Wednesday in The Journal of the American Medical Association.

The investigators had 82 men and women rate the pain caused by electric shocks applied to their wrist, before and after taking a pill. Half the participants had read that the pill, described as a newly approved prescription pain reliever, was regularly priced at $2.50 per dose. The other half read that it had been discounted to 10 cents. In fact, both were dummy pills.