How Does Observational Learning Produce Placebo Effects? A Model Integrating Research Findings

Abstract

There is a growing body of evidence proving that observational learning, in addition to classical conditioning and verbal suggestions, may induce both placebo analgesia and nocebo hyperalgesia. However, much less is known about the mechanisms and factors influencing placebo effects induced by observational learning. The paper critically reviews the research findings in the field in the context of Bandura's social learning theory. We apply Bandura's taxonomy of the sources of social learning (behavioral, symbolic, and verbal modeling) and discuss the results of previous studies. Critical points in the placebo effects induced by observational learning are identified. We discuss aspects of behavior presented by the model (both verbal and non-verbal) involved in the formation of placebo effects induced by observational learning as well as the role of expectancies in this process. As a result, we propose a model that integrates the existing research findings. The model shows the main ways of transmission of pain-related information from the model to the observer. It highlights the role of expectancies and the individual characteristics of the observer in formation of placebo analgesia and nocebo hyperalgesia induced by observational learning. Finally, we propose future research directions based on our model.

Keywords: modeling; nocebo hyperalgesia; observational learning; placebo analgesia; social learning.

FIGURE 1

Formation of placebo effects induced by observational learning. Figure depicts the ways of transmission of information concerning pain from the model to the observer: (1) behavioral modeling, (2) verbal modeling, and (3) symbolic modeling. The information conveyed to the observer may contribute to the formation of expectancies of analgesia/hyperalgesia and thereby induce the placebo/nocebo effect. Individual characteristics of the observer, including empathy, are also involved in the formation of observationally induced analgesia and hyperalgesia. The relationships confirmed in previous studies are drawn with a solid line, while those which seem to be possible but are not yet confirmed are depicted with a dashed line.