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Related Experiment Video

Updated: Nov 29, 2025

Applying Incongruent Visual-Tactile Stimuli during Object Transfer with Vibro-Tactile Feedback

Applying Incongruent Visual-Tactile Stimuli during Object Transfer with Vibro-Tactile Feedback

Published on: May 23, 2019

A virtual experimenter does not increase placebo hypoalgesia when delivering an interactive expectancy manipulation.

Bjoern Horing¹, Sarah C Beadle², Zachariah Inks³

¹Affective Neuroscience Group, Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany. b.horing@uke.de.

Scientific Reports

|November 24, 2020

Summary

A virtual experimenter (VEx) successfully induced expectancy effects on pain, but the VEx delivery method influenced outcomes differently than text-only delivery. This highlights diverse mechanisms underlying placebo effects in pain research.

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Area of Science:

Psychology
Neuroscience
Pain Research

Background:

Standardization and unblinding are significant challenges in studying expectancy effects on pain.
Computer-controlled systems offer a potential solution for consistent and unbiased experimental delivery.

Purpose of the Study:

To evaluate a computer-controlled virtual experimenter (VEx) for standardizing the delivery of expectancy manipulations in pain research.
To investigate the interaction between expectancy (placebo vs. no-treatment) and delivery method (VEx vs. text-only) on pain perception.

Main Methods:

Fifty-four subjects completed a heat pain protocol with baseline and retest sessions.
An expectancy manipulation (placebo or no-treatment) was delivered via VEx or text-only.
Pain ratings and psychological measures were recorded to assess outcomes.

Main Results:

An interaction was observed between expectancy and delivery method on pain reduction.
Placebo led to lower pain in text-only conditions, but VEx showed similar pain reduction for both placebo and no-treatment.
Decreases in negative mood and anxiety mirrored this interaction, and pain relief expectation moderated pain changes.

Conclusions:

An automated protocol using a VEx was successfully developed for inducing expectancy effects on pain.
The VEx's effect, irrespective of treatment, may involve attention and locus of control, suggesting diverse expectancy mechanisms.
Findings have implications for both pain research methodology and the development of computer-based therapeutic applications.