Placebos administered without deception reduced both self-reported and neural measures of emotional distress in a study published in Nature Communications.
“These findings provide initial support that nondeceptive placebos are not merely a product of response bias — telling the experimenter what they want to hear,” said study coauthor Ethan Kross, PhD, professor of psychology and management at the University of Michigan, “but represent genuine psychobiological effects.”
The findings stem from a pair of experiments conducted by a team of researchers from Michigan State University, East Lansing; the University of Michigan, Ann Arbor; and Dartmouth College, Hanover, New Hampshire.
For the investigation, participants were divided into two groups. Those in the nondeceptive placebo group read about placebo effect, inhaled a saline solution nasal spray, and were told the nasal spray contained no active ingredients but could help reduce negative feelings if participants believed it would. Participants in a comparison control group inhaled the same inactive saline solution nasal spray but were told the spray improved physiological readings for the study. All participants viewed a series of emotional images.
In the first experiment, participants in the nondeceptive placebo group had less self-reported emotional distress during the arousing negative picture viewing task, researchers found. During the second experiment, participants in the nondeceptive placebo group showed lower electrical brain activity, reflecting less emotional distress.
“Our findings demonstrate an objective non-deceptive placebo effect on a neural biomarker that is relevant for emotion regulation and conditions characterized by emotional distress,” researchers wrote. “Future research should examine the generalizability of these findings to other populations, domains, and biomarkers.”
Researchers are currently following up on the findings with a study investigating nondeceptive placebos for COVID-19-related stress.