Red induces hyperalgesia and white induces hypoalgesia regardless of pain modality.

Colors are an important factor that influences different aspects of people's lives. However, little is known about the effects of colors on pain. This preregistered study aimed to investigate whether the type of pain affects the impact of colors on pain intensity.

When one suffers less, all suffer less: Individual pain ratings are more effective than group ratings in producing placebo hypoalgesia.

Background: Placebo hypoalgesia can be induced by observing a person (model) whose pain relief is the result of the use of an inert substance or procedure. This study examined whether verbal modelling, that is, showing pain ratings provided by other people, is sufficient to induce placebo hypoalgesia.

Methods: Participants from the experimental groups were acquainted with pain ratings (presented on VASs) derived from a single person (groups 1 and 3) or a group of people (groups 2 and 4) that were allegedly subjected to the same painful procedure.

Order does matter: the combined effects of classical conditioning and verbal suggestions on placebo hypoalgesia and nocebo hyperalgesia.

In most experimental studies in which verbal suggestion and classical conditioning are implemented together to induce placebo effects, the former precedes the latter. In naturally occurring situations, however, the information concerning pain does not always precede but often follows the pain experience. Moreover, this information is not always congruent with experience.

One of us or one of them? The effects of the model's and observer's characteristics on placebo analgesia induced by observational learning.

Previous studies have proved that observational learning can induce placebo analgesia, but the factors that influence observationally induced placebo analgesia have not yet been extensively examined. The primary goal of this study was to investigate the effect of information about the role that the observed person (model) plays in the experiment on the magnitude of the observationally induced placebo effect. This study also examined the contribution of the observer's empathy, conformity and fear of pain to the placebo analgesia induced by observational learning.

Nocebo hyperalgesia can be induced by classical conditioning without involvement of expectancy.

Influential theoretical accounts take the position that classical conditioning can induce placebo effects through conscious expectancies. In the current study two different conditioning procedures (hidden and open) were used to separate expectancy from conditioning in order to reveal the role of expectancy in the formation of nocebo hyperalgesia. Eighty-seven healthy females were randomly assigned to three groups (hidden conditioning, open conditioning, and control).

Memory of pain in adults: a protocol for systematic review and meta-analysis.

Background: The way pain is remembered and reported can affect medical decisions taken by patients and health-care professionals. Memory of pain has been investigated extensively for the past few decades; however, the results of previous studies are highly variable, indicating that the recollection of pain can be accurate, overestimated or underestimated. It is therefore difficult to conclude how well pain is remembered.

To Experience or to Be Informed? Classical Conditioning Induces Nocebo Hyperalgesia even when Placebo Analgesia Is Verbally Suggested-Results of a Preliminary Study.

Objective: To investigate whether direct experience (i.e., classical conditioning) or verbal suggestion is more important in inducing nocebo hyperalgesia, five groups (total sample size, N = 99) were studied: conditioning, congruent conditioning, incongruent conditioning, verbal suggestion, and control.

Color Hurts. The Effect of Color on Pain Perception.

Background Research suggests that colors may have an effect on human behavior, cognition, and emotions; however, little is known about their influence on pain perception. The aim of these two studies was to investigate whether colors have an impact on pain perception and to find the mechanism that underlies the influence of colors on pain. Methods In both studies, participants received electrocutaneous pain stimuli of the same intensity preceded by one of six colors (red, green, orange, blue, pink, or yellow) or a blank slide, which served as a control condition.

Rewarded placebo analgesia: A new mechanism of placebo effects based on operant conditioning.

Background: Placebo analgesia is explained by two learning processes: classical conditioning and observational learning. A third learning process, operant conditioning, has not previously been investigated as a mechanism of placebo effects. We aimed to induce placebo analgesia by operant conditioning.