Graduation Date
Spring 2025
Document Type
Thesis
Program
Master of Arts degree with a major in Psychology, option Academic Research
Committee Chair Name
Carrie Aigner
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Amanda Hahn
Second Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Third Committee Member Name
Ethan Gahtan
Third Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Keywords
Open label, Open-label, Placebo, Motivation, Expectancy, Anxiety
Subject Categories
Psychology
Abstract
Placebo effects occur when an individual receives an inactive treatment that should be unable to provide therapeutic benefits but still demonstrates meaningful improvements in health. Open-label placebos extend this phenomenon by providing full disclosure to individuals that they are receiving a placebo, as opposed to traditional placebo treatments that utilize deception. The role of expectancy as a mechanism of change in placebo has received some mixed results in open-label placebo studies. To the author’s knowledge, motivation for change has not been examined in open-label placebo. The current study examined the role of motivation as a mechanism of placebo responses. To induce a state of public speaking anxiety, participants were informed that they would be required to give an online presentation that would be analyzed by judges. Participants were then assigned to one of four groups and given scripts that were designed to manipulate their motivation and expectations regarding a placebo relaxation intervention. Pre- and post-intervention anxiety was measured. It was hypothesized that there would be a main effect for both expectancy and motivation and an expectancy by motivation interaction on anxiety. A total of 51 participants were included in the final analysis. Results revealed that the scripts were unable to effectively manipulate expectancy and motivation in participants, but that participants across conditions did show a significant drop in anxiety scores in the posttest measurement, when compared to the pretest. In conclusion, while expectancy and motivational manipulations failed, the main effect for time suggests that participants may have experienced a placebo effect after being exposed to the placebo intervention. Limitations are discussed.
Citation Style
APA
Recommended Citation
Worthington, Joshua, "Investigating the role of motivation in open-label placebo responses" (2025). Cal Poly Humboldt theses and projects. 2297.
https://digitalcommons.humboldt.edu/etd/2297