The study aimed to determine if the pain assessment skills of the individual being observed influence observationally induced placebo effects in pain. Participants were randomly assigned to two experimental groups and one control group. In the experimental groups, participants observed the responses to the placebo of a model who had previously shown either high accuracy (high-accuracy group) or low accuracy (low-accuracy group) in differentiating the intensity of pain stimuli. The model exhibited less pain in response to pain stimuli when a placebo was administered, and more pain when no placebo was given. The control group did not observe anyone experiencing pain during the experiment. All participants then received a series of pain stimuli of the same intensity, half of which were administered with a placebo, and rated the intensity of pain. Pain-related expectations of the participants were also measured. Observational learning caused a form of nocebo hyperalgesia in the participants, leading to a slight increase in response to stimuli applied with a placebo and significant increase in pain in response to stimuli applied without a placebo in participants from the high-accuracy group. Observational learning resulted in pain-related expectations, regardless of the observed model's accuracy. However, these expectations mediated participants' responses to pain only in the low-accuracy group. The findings suggest that the pain assessment skills of the observed model play a significant role in shaping observers' pain-related expectations and their responses to a placebo. Perspective This article demonstrates that individuals perceived as having skills in pain assessment can effectively influence observers' pain responses. Including well-adjusted patients as models to showcase the potential positive effects of treatment can be beneficial.

The aim of the study was to examine the direction of the secular changes in the waist and hips circumferences, as well as selected associated body proportions, among children and adolescents from Kraków, Poland. The study group included 8–18-year-olds examined in three cross-sectional studies (1983, 2010, and 2020). The analyzed characteristics included body height, circumferences of the waist and hips, which were used to calculate Waist-to-Hip Ratio (WHR), and Waist-to-Height Ratio (WHtR). There was a secular increase regarding the majority of the analyzed features, particularly for the younger children (i.e., prepubertal/early pubertal age). The trends were also especially evident when comparing the results of the 1983 series to the results of their peers examined in 2020. An opposite trend was noted in adolescent girls. The observed changes reflect the secular trend resulting from changes in body composition and fat distribution happening due to alterations in the lifestyle and socio-economic environment of the population over the years. It should also be stressed that the increase in the studied characteristics occurred mainly in younger children. This suggests that the observed changes may have resulted from a shift in the age of maturation and also from the personal and social motivators characteristic for late adolescence.

Research suggests that negative affective states, such as fear and anxiety that accompany placebo treatment may be considered predictors of placebo hypoalgesia and nocebo hyperalgesia. There is also data showing that the likelihood of developing nocebo hyperalgesia is related to the relatively stable tendency to experience these negative emotions. We aimed to summarize the current state-of-the-art in studies and theoretical models on the role of fear and anxiety in placebo hypoalgesia/nocebo hyperalgesia, with a clear differentiation between these emotions. The role of fear and anxiety accompanying placebo treatment in shaping placebo effects is often studied, but less attention has been given to pretreatment emotional states. We propose a model that combines knowledge from the emotional and pain paradigms with the current research on placebo hypoalgesia and nocebo hyperalgesia to present the involvement of fear and anxiety as traits, as well as pretreatment and posttreatment states of fear and anxiety to placebo effects. The main assumption of the model is that trait fear, trait anxiety, and related pretreatment affective states impact pain perception differently. Heightened fear is associated with decreased pain perception, while heightened anxiety is linked to increased pain perception. Consequently, heightened pretreatment fear may lead to reduced nocebo hyperalgesia and enhanced placebo hypoalgesia, while heightened pretreatment anxiety may result in decreased placebo hypoalgesia and increased nocebo hyperalgesia. In conclusion, we propose future research directions and clinical applications of the model. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Calibration of pain stimuli is critical in experimental pain research because it makes it possible to adjust stimulus intensity to match individual pain sensitivity. Despite its importance, precise descriptions of calibration procedures are lacking in the literature, thus hindering the ability to replicate studies. The aim of this systematic review is to fill this gap by evaluating and categorizing calibration methods used in pain studies involving electrodermal stimuli in healthy adult volunteers. A search of 9 databases identified 51 relevant articles published between 2018 and 2024, which were analyzed regarding calibration methods and their effectiveness. The review identified 2 main calibration methods, namely the method of limits and the staircase method, along with 3 techniques, namely ascending, descending, and random calibration. The findings reveal that 69% of studies did not verify the effectiveness of their calibration processes. Among those that did, varying degrees of success were observed. The ascending calibration technique was less precise, while combined ascending and pseudorandom calibration offered better matching of stimulus intensity but still required optimization. However, the data were insufficient to definitively determine which method was the most accurate. There is still a lack of consistent approaches to reporting calibration in the literature, which can lead to difficulties in interpreting results and comparing different studies. Future research should focus on comparing these methods to identify the most effective approaches and explore factors influencing calibration success.

Effective pain calibration is critical in experimental pain research, particularly in studies utilizing individually adjusted electrocutaneous stimuli. However, methods used to match subjective pain intensity with objective stimulation parameters vary across studies and their effectiveness remains unclear. The present secondary analysis compared calibration outcomes from three independently conducted experiments (N = 401) that applied distinct pain calibration procedures. Each method aimed to identify individually adjusted stimulus intensities. To evaluate calibration accuracy, baseline trials were analyzed during which participants received predetermined stimuli and rated perceived pain intensity. Calibration effectiveness was operationalized as the correspondence between actual pain ratings and target values. The results revealed significant differences in calibration effectiveness between procedures. Calibration, which employed an ascending technique with an additional pseudo-random series, resulted in significantly smaller differences between the anticipated and perceived pain levels, suggesting that the method of calibration can substantially influence the precision of pain induction. Additionally, differences were observed between participants' pain expectations and the target pain values. Further analysis confirmed that higher pain expectations were positively correlated with higher pain ratings, supporting the predictive role of expectancy in pain perception. These findings underscore the critical importance of calibration procedures in experimental pain research and emphasize the need for further studies to develop more precise and reliable calibration methods. PERSPECTIVE: This study demonstrates that the effectiveness of pain calibration varies significantly across procedures. The findings highlight the methodological relevance of calibration in experimental pain research and point to the need for further investigation into how different calibration strategies shape pain measurement accuracy.

This study compares the effectiveness of verbal modeling, symbolic modeling, and verbal suggestion in inducing nocebo hyperalgesia. It is the first study to examine the contribution of stress to observationally induced nocebo hyperalgesia. This study’s experimental groups represented various sources of social information: a group of people participating in the study (verbal modeling), a single participant (symbolic modeling), and an experimenter (verbal suggestion). During the experiment, participants received electrocutaneous stimuli at the same intensity, half of which were applied with a placebo (sham device). Participants in the verbal modeling group were acquainted with pain ratings that had allegedly been provided by other participants. The ratings suggested that other participants experienced more pain in the placebo trials than in the control trials. In the symbolic modeling group, participants observed a model experiencing more pain in the placebo than in the control trials. In the verbal suggestion group, participants received a verbal suggestion of hyperalgesia in the placebo trials and no suggestion in the control trials. No manipulations were used in the control group. To investigate whether nocebo hyperalgesia is stable over time, an additional extinction phase was conducted. Nocebo hyperalgesia was induced by verbal modeling only and was mediated by expectancy. Stress was a significant moderator of the induced effect. Nocebo hyperalgesia was extinguished during the extinction phase. The obtained results provide potential implications for minimizing nocebo hyperalgesia in clinical practice by, for instance, controlling patients’ expectancies and stress levels.