Want to be fit? Start with your mind! The role of the placebo effect in physical fitness in children: a preliminary systematic review and meta-analysis.

Physical activity is crucial to prevent and reduce excess body mass. The placebo effect can influence the outcomes of fitness-related interventions; however, this topic has not yet been extensively investigated in children. Summarising the data on placebo effects in fitness-related interventions is essential to understand this problem better. A systematic review of PubMed, Cochrane, PsycINFO, PsycARTICLES, TripDatabase and Embase was carried out. A meta-analysis of the results of studies with comparable research plans was performed. There were significant differences, favouring the placebo intervention. At the final follow-up, the children in placebo groups had higher maximal heart rates, shorter recovery times, longer ergometry phases, running time and lower peak and average perceived exertion than the control. The placebo effect is present in fitness-related parameters in children, regardless of the Body Mass Index status. It is crucial, as for youth with excess body mass, it is difficult to be active, especially to show appropriate levels of motivation and involvement. Importantly, the benefits of the placebo were the strongest in the motivation/ engagement-related parameters and self-assessed exertion. Notably, the nocebo effect was not observed, which is advantageous when considering placebo interventions in practice.

No(cebo) Vax: COVID-19 Vaccine Beliefs Are Important Determinants of Both Occurrence and Perceived Severity of Common Vaccines' Adverse Effects.

This study highlights the role of psychological influences in triggering and amplifying the adverse effects of the COVID-19 vaccine (i.e., nocebo effects). Fear, beliefs, and expectations about the COVID-19 vaccine, trust in health and scientific institutions, and stable personality traits were measured in 315 adult Italian citizens (145 men) during the 15-min waiting time after vaccination. The occurrence and severity of 10 potential adverse effects were assessed 24 hr later. Nonpharmacological variables predicted nearly 30% of the severity of the vaccine's adverse effects. Expectations are important determinants of adverse effects from vaccines, and the results of the path analyses show that these expectations stem primarily from people's vaccine beliefs and attitudes, which can be changed. Implications for increasing vaccine acceptability and limiting the nocebo effect are discussed.

Age as a moderator in the interplay among locus of control, coping, and quality of life of people with chronic pain.

OBJECTIVE: Identifying the factors that determine the quality of life of patients with chronic pain is an integral part of developing interventions to reduce the negative impact of persistent pain. Locus of control (LoC) could play an important role in adaptation to prolonged pain, but the results of studies are inconsistent. We examined the link between pain LoC and quality of life. Moreover, we investigated whether the relationship between LoC and quality of life is mediated by passive and active coping, and whether age moderates the LoC-coping relationship. METHODS: The study was cross-sectional, and variables (internal, chance and powerful-others LoC, pain coping strategies, average pain intensity, and quality of life) were assessed via questionnaires in a sample of 594 individuals (67% females) with chronic pain who were 18-72 (mean: 36) years of age. RESULTS: Mediation and moderated mediation analyses were conducted. Internal and external LoC were associated, respectively, with better and with worse quality of life. Passive coping mediated the association between the powerful-others dimension of LoC and poor quality of life. Additionally, indirect effects of internal LoC on quality of life via passive and active coping were found. The relationship between the powerful-others dimension of LoC and coping was stronger for middle-aged and older individuals than for younger individuals. CONCLUSIONS: This study contributes to a better understanding of the mechanisms linking LoC with quality of life of patients with chronic pain. Depending on the age, control beliefs might translate differently into strategies used to cope with pain, and thus into quality of life.

The Effect of the Model's Social Status on Placebo Analgesia Induced by Social Observational Learning.

BACKGROUND: Placebo analgesia can be induced by social observational learning. The aim of this study was to determine whether this effect can be influenced by the social status of a model. METHODS: Healthy volunteers were randomly assigned to three groups: a group that observed a video featuring a high-status model (introduced as a professor), a group that observed a video featuring a low-status model (introduced as a janitor), and a control group. Participants observed videos showing a model (of high or low status) undergoing the experimental procedure, during which he received pain stimuli. In each group, half of participants watched a video in which the model rated blue stimuli as more painful (6-8 on the numeric rating scale) and orange stimuli as less painful (1-3 on the numeric rating scale), whereas the other half of participants watched a video in which the model rated orange stimuli as more painful and blue stimuli as less painful. Participants in the control group did not watch any video. Then, all participants received 16 electrocutaneous pain stimuli of the same intensity, preceded by either blue or orange colors. The perceived social status of the model and the trait empathy of participants were measured. RESULTS: Placebo analgesia was induced in both experimental groups, yet no difference in the magnitude of the effect was found. However, we found that the participants' individual ratings of the model's social status predicted the magnitude of placebo analgesia. CONCLUSION: This is the first study to show that the perception of a model's social status is related to the magnitude of placebo analgesia induced by observational learning.

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. METHODS: Participants in groups with conditioning experienced more intensive pain stimuli after presentation of a white circle. In the congruent conditioning group, suggestion that the circle would precede more intensive pain stimuli was additionally provided, whereas in the incongruent conditioning group, the opposite suggestion was used. Control and verbal suggestion groups received pain stimuli of one intensity; however, the latter received suggestion that a circle would precede pain stimuli of higher intensity. RESULTS: The nocebo effect was observed in all conditioning groups, regardless of the verbal suggestions used. Moreover, the experience of hyperalgesia was able to nullify the effect of the verbal suggestion of analgesia. Incongruence between verbal suggestion and pain experience produced expectancies that affected nocebo hyperalgesia. CONCLUSIONS: The results of this preliminary study suggest that direct experience seems to be more important than verbal suggestion in inducing nocebo hyperalgesia.

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. In the first study, the intensity of experienced pain was measured; in the second study, both experienced and expected pain was measured. Results The studies revealed that colors increased the intensity of experienced pain in comparison with the noncolor condition (blank slide), regardless of both the sex of participants and whether they noticed a relationship between colors and pain intensity. Particularly, participants rated pain stimuli preceded by red as being more painful compared with pain stimuli preceded by other colors, especially green and blue. Conclusions It is concluded that colors have an impact on pain perception. Our results have important implications for the color lights paradigm applied in studies on placebo effects.

How Classical Conditioning Shapes Placebo Analgesia: Hidden versus Open Conditioning.

Objective: To investigate the influence of expectancy of pain intensity, fear of pain (trait), and fear (state) on the effectiveness of hidden and open conditioning to produce placebo analgesia. Methods: A total of 90 healthy female volunteers were randomly assigned to three groups (hidden conditioning, open conditioning, and control) that received electrical stimuli preceded by either orange or blue lights. One color was paired with painful stimuli (control stimuli) and the other color was paired with nonpainful stimuli (conditioned stimuli) in both the hidden and open conditioning groups. Only participants in the open conditioning group were informed about this association. In the control group, both color lights were followed by control stimuli. In the testing phase, both colored lights were followed by identical control stimuli. Participants rated pain intensity, expectancy of pain intensity, fear, and fear of pain. Results: A significant analgesic effect was found only in the hidden conditioning group, where no explicit verbal suggestions were provided. Hidden conditioning had an effect on expectancy and fear-participants in the hidden conditioning group expected less pain and experienced less fear in relation to conditioned stimuli. Fear was the only predictor of placebo analgesia in the hidden conditioning group. Neither expectancy of pain intensity nor fear of pain predicted placebo analgesia. Conclusions: Fear seems to be a more important factor than expectancy in producing placebo analgesia induced by hidden conditioning.

The Influence of State and Trait Anxiety on the Memory of Pain.

OBJECTIVE: The study aimed to assess the accuracy of memories of both pain and the state anxiety that accompanies experimentally induced pain and to investigate the factors that influence the memory of experimental pain. METHODS: Forty-nine healthy female volunteers participated in the study. The participants received three electrocutaneous pain stimuli during the first phase of the study and rated the pain intensity, pain unpleasantness, and state anxiety they felt at that moment. Trait pain anxiety was measured by the Pain Anxiety Symptoms Scale and the Fear of Pain Questionnaire. During the second phase of the study, three or six months later (depending on the experimental group), the participants were asked to rate the pain intensity, pain unpleasantness, and state anxiety they had felt during the first phase of the study. RESULTS: Recalled pain intensity and unpleasantness and the state anxiety that accompanied the pain experience were remembered accurately, regardless of the recall delay. Both recalled pain intensity and unpleasantness were predicted by experienced pain, experienced and recalled state anxiety, and trait pain anxiety, that is, scores for physiological anxiety, cognitive anxiety, escape/avoidance, and severe pain. CONCLUSIONS: The present study demonstrates that a specific type of trait anxiety (pain anxiety) influences the memory of pain. The study is not only the first to investigate the influence of trait anxiety on the memory of experimental pain, it also is the first study to determine the effect of a specific form of anxiety (pain anxiety) on the memory of experimentally induced pain.

The Effect of Positive Affect on the Memory of Pain.

The aim of the study was to assess the accuracy of the memory of experimentally induced pain and the affect that accompanies experimentally induced pain. Sixty-two healthy female volunteers participated in the study. In the first phase of the study, the participants received three pain stimuli and rated pain intensity, pain unpleasantness, state anxiety, and their positive and negative affect. About a month later, in the second phase of the study, the participants were asked to rate the pain intensity, pain unpleasantness, state anxiety, and the emotions they had felt during the first phase of the study. Both recalled pain intensity and recalled pain unpleasantness were found to be underestimated. Although the positive affect that accompanied pain was remembered accurately, recalled negative affect was overestimated and recalled state anxiety was underestimated. Experienced pain, recalled state anxiety, and recalled positive affect accounted for 44% of the total variance in predicting recalled pain intensity and 61% of the total variance in predicting recalled pain unpleasantness. Together with recent research findings on the memory of other types of pain, the present study supports the idea that pain is accompanied by positive as well as negative emotions, and that positive affect influences the memory of pain.

Memory of pain induced by physical exercise.

The aim of this study was to assess the memory of pain induced by running a marathon and the factors that influence it. Sixty-two marathon runners participated in the study, which comprised two phases. Immediately after a participant had reached the finishing line of the marathon, they were asked to rate the intensity and the unpleasantness of their pain and the emotions they felt at that time. Either three or six months later they were asked again to rate the intensity and the unpleasantness of the same pain experience. Regardless of the length of recall delay, participants underestimated both recalled pain intensity and unpleasantness. The pain and negative affect reported at the time of the pain experience accounted for 24% of the total variance in predicting recalled pain intensity and 22% of the total variance in predicting recalled pain unpleasantness. Positive affect at the time of pain experience was not a significant predictor of both the recalled pain intensity and pain unpleasantness. It is concluded that pain induced by physical exercise is not remembered accurately and the pain and negative affect experienced influence recall. Further research is needed on the influence of positive affect on the memory of pain.

Memory of pain and affect associated with migraine and non-migraine headaches.

The main aims of this study were to assess memory of pain and pain-related affect in headache sufferers and to compare the pain memories of individuals who suffer from migraines and those who experience non-migraine headaches. A total of 313 women participated in the study, 86 of whom had a diagnosis of migraine headache. The women rated their state anxiety about having a headache, the intensity and unpleasantness of headache pain, and their emotions while actually experiencing a headache. Either three or six months later, the participants were asked to recall their state anxiety, the intensity and unpleasantness of pain, and the emotions they had felt. Regardless of the length of recall delay or migraine diagnosis, participants accurately remembered both pain intensity and unpleasantness. Together, recalled anxiety, experienced pain and recalled positive affect were the most important predictors of memories for headache, accounting for 41% and 37% of the total variance in recalled pain intensity and unpleasantness, respectively. However, participants overestimated recalled positive and negative affect. The effect of recalled affect on memory of headache, together with the overestimation of recalled affect, suggests that although memory of headache is accurate, it is influenced by distorted memories of affect.

Can observational learning reinforce open-label placebo hypoalgesia?

ABSTRACT: Previous research has indicated that an open-label placebo can reduce pain in both healthy participants and patients with chronic pain. Because nondeceptive placebos seem to be an effective and more ethical alternative to deceptive placebos, optimizing this kind of treatment is essential. Observational learning was previously shown to induce the deceptive placebo effect; therefore, this study aimed to verify its effectiveness in fortifying the open-label placebo effect. Healthy volunteers (N = 117) were randomly assigned to 4 groups: open-label placebo with observational learning (OLP + OBL), open-label placebo (OLP), deceptive placebo with observational learning (OBL), or control group. Participants underwent baseline and testing measurements, during which they self-reported pain induced by heat stimulation. Between assessments, placebo cream was openly administered in the OLP and OLP + OBL groups. The OLP + OBL group next watched a model experiencing hypoalgesia after cream application. In the OBL group, participants received placebo cream with no information about its effect, and then they watched the model. The placebo effect was successfully evoked in all experimental groups (OLP + OBL, OLP, and OBL), which confirms the effectiveness of both open-label and deceptive placebo interventions for pain reduction. However, the hypoalgesic effect was of similar magnitude in the OLP and OLP + OBL groups, which indicates that observation did not contribute to the effect. The results showed that reinforcing the open-label placebo by observational learning may be redundant, but more research is needed to confirm these findings.

Diet, gym, supplements, or maybe it is all in your mind? A systematic review and meta-analysis of studies on placebo and nocebo effects in weight loss in adults.

INTRODUCTION: There is evidence that placebo and nocebo effects are significant for many conditions, but their impact on weight loss has not yet been well described. MATERIAL AND METHODS: A systematic review of studies indexed on PubMed, Cochrane, PsycINFO, PsycARTICLES, TripDatabase, and Embase was carried out. Studies (1) with at least two study groups - placebo and a corresponding control group; (2) published in English; and (3) focusing on adults participating in weight loss programs or on placebo/nocebo effects in weight loss were included. Synthesis and meta-analysis of the results of studies with comparable research plans were performed. RESULTS: Some preliminary trends suggesting placebo and nocebo effects in weight loss were found. Placebo effects manifested in trends towards a slightly greater reduction of Body Mass Index (BMI) and body fat ratio in the placebo compared with the control groups. On the other hand, in one study, it was found that the expectancy effects of taking oral weight-loss agents might be disadvantageous (i.e., because they elicit a nocebo effect on weight loss). CONCLUSION: The findings suggest a possibility that the nocebo effect may occur when an intervention has a medical context. In contrast, the placebo effect can be observed in cases where the intervention is of a different nature. However, considering the low number of studies analyzing the use of placebos in weight loss, new primary research is needed.

Social Learning of Placebo Effects in Pain: A Critical Review of the Literature and a Proposed Revised Model.

Relatively recently, in 2009, experimental studies were undertaken to determine the role of social observational learning in forming hypoalgesic, analgesic and hyperalgesic responses to a placebo. The research findings obtained in studies published before 2018 were integrated and formed the basis of the theoretical model of social learning of placebo effects in pain proposed by Bajcar and Babel. This model considered the involvement of different types of modeling (ie, behavioral modeling, symbolic modeling, and verbal modeling) in shaping placebo hypoalgesia/analgesia and nocebo hyperalgesia. The model assumed that pain expectancies might be involved in observationally induced placebo effects in pain and that the effectiveness of observational learning in shaping placebo effects could be moderated by the observer's dispositions, especially empathy. Based on the latest research data, we propose a modified and significantly extended version of this model. The revised model includes the involvement of particular types of modeling in placebo effects and their role in shaping conscious pain-related expectancies. It explains the role of dispositional empathy in shaping observationally induced placebo effects. Notably, the extended version of the model considers the contribution of the characteristics of the observed person to the magnitude of placebo effects induced by social learning. PERSPECTIVE: The paper proposes a comprehensive theoretical approach to explaining the role of observational learning in shaping placebo effects in pain. The proposed model emphasizes the potential of this form of learning in shaping placebo responses and indicates factors that can modify the effectiveness of observational learning.

Treatment of last resort? Psychological therapy seeking in chronic pain patients.

OBJECTIVE: Our goal was to assess how many chronic pain patients seek psychological treatment for their condition and what psychological and demographic characteristics are associated with that decision. METHODS: The association between pain intensity, quality of life and psychological treatment seeking was tested in two hypothetical models which differed according to beliefs about either external or internal control over pain. RESULTS: A minority of patients had experience with psychological treatment of chronic pain. Patients who had that experience were younger, suffered from more intense pain, and applied many more coping strategies than patients who never tried this kind of treatment. Intense pain and low quality of life motivated chronic pain patients to seek psychological treatment only if they believed that doctors could control their pain. DISCUSSION: The study results stress the importance of diversifying the methods used to treat chronic pain and educating patients about the benefits of psychological treatment. Low numbers of chronic pain patients who take advantage of psychological treatment indicate that encouragement from medical professionals might be necessary.

Body Image Measured via the Fremantle Awareness Questionnaire in Individuals With and Without Pain: A Systematic Review and Meta-Analysis.

Research suggests that pain negatively affects body image, and body image may also influence reported pain levels. This review aims to summarize the literature on differences in body image distortion between individuals with pain compared to pain-free individuals. The review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020 statement and an a priori preregistered protocol. The literature was searched using 5 electronic databases. Studies assessing body image with the Fremantle Awareness Questionnaire (FAQ) in individuals with and without pain were eligible for inclusion. Screening and selection of eligible studies were performed by independent reviewers. Methodological quality was assessed with the Joanna Briggs Institute critical appraisal tool. Meta-analyses, meta-correlations, and metamean analyses were performed using random-effect models. The primary outcome was the FAQ score; secondary outcomes were reported pain variables. Data from individuals with pain (n = 2277) and without pain (n = 615) were summarized. Significant body image distortions were found in individuals with pain compared to individuals without pain. Compared to pain-free individuals, the pain group rated significantly higher in the FAQ when experiencing back pain (standardized mean differences=1.33, 95% confidence interval=.88-1.77) or other body parts (standardized mean differences=1.25, 95% confidence interval=.51-1.99). The results of meta-correlation analyses confirmed the positive relationship between body image distortion and pain intensity (r = .31), pain at rest (r = .31), or pain during movement (r = .36), but not for pain duration. A difference in mean FAQ results was observed between individuals with pain in different areas (knee and back). PERSPECTIVE: This review confirms differences in body image distortion between pain and pain-free individuals. Pain intensity was correlated with altered body perception, but not pain duration. A moderate correlation was observed between body image distortion and reported pain variables. Body image was more impaired by knee pain than back pain. REGISTERED PROTOCOL AT PROSPERO: CRD42022309937; https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022309937.

Placebo Hypoalgesia and Nocebo Hyperalgesia Induced by Observational Learning May Be Difficult to Disentangle in a Laboratory Setting.

Observational learning (OBL) (seeing pain/pain treatment in others) can evoke placebo hypoalgesia and nocebo hyperalgesia. Data that compare these effects and illuminates the role of expectations and empathy are scarce. Healthy participants (n = 105) were randomized to: 1) placebo OBL, 2) nocebo OBL, or 3) no-observation control group. OBL consisted of a model simulating pain relief or increase after a sham ointment was applied to one arm. Pain was evoked with thermal stimuli on both arms (ointment, contralateral) at baseline and postobservation. Expectations, pain ratings, and physiological data (eg, skin conductance level) were collected. A 3 × 2 × 2 (Group × Arm × Phase) mixed analyses of variance revealed a 3-way interaction that confirmed that OBL modulates pain: F(2, 93) = 6.08, P = .003, ηp2 = .12. Significant baseline-to-post-observation pain increases were shown in the nocebo OBL group, with a bigger increase for the arm with ointment (both P ≤ .007). In the placebo OBL group, pain was higher for the contralateral relative to the ointment arm (P < .001). Baseline-to-post-observation pain increase was significant for the contralateral arm (P < .001). Expectation mediated these effects. Skin conductance level decreased over time during ointment trials in the nocebo OBL group, suggesting reduced physiological arousal. The findings illustrate that OBL modulates pain through expectations. In the placebo OBL group, the pain did not decrease for the ointment but increased for the contralateral stimuli, which may reflect nocebo learning. Experimental OBL paradigms typically examine relative differences between ointment and contralateral cues. This can complicate disentangling placebo hypoalgesia and nocebo hyperalgesia in laboratory settings. Implications for existing theories are discussed. PERSPECTIVE: Data that systematically compare placebo hypoalgesia and nocebo hyperalgesia induced by OBL are scarce. The current work illustrates that these effects may be more difficult to disentangle than previously assumed, which could have implications for existing theories on OBL and placebo effects and their translation to clinical practice.

Pain memory in children: a systematic review and meta-analysis with a meta-regression.

ABSTRACT: The aim of this systematic review and meta-analysis was to analyze the accuracy of memory of pain and the variables that may influence it in children with acute, experimental, and chronic pain. We conducted a search in electronic databases from inception to February 11, 2022. Twelve observational studies and 3 randomized controlled studies were included in the study. The main outcome measure was the accuracy of the memory of the pain intensity (experienced/recalled). To compare the outcomes reported by the studies, we calculated the standardized mean difference (SMD) over time for the continuous variables. The overall meta-analysis showed a small effect size in favor of an overestimation of experienced pain intensity (SMD = 0.28). Subanalyzing per pain context, there was a small effect size in favor of overestimation in the clinical context (SMD = 0.33), but there was no evidence of any change in the accuracy of memory of pain in the experimental context (SMD = 0.07). The mean age of the participants and the proportion of girls significantly predicted the accuracy of the memory of pain. The period since the experienced pain measurement, the intensity of expected and recalled fear, trait anxiety, and anxiety sensitivity did not significantly predict the accuracy of the memory of pain. Children showed an overestimation in pain memory between the experienced and recalled intensity of acute pain, especially in a clinical context. Furthermore, only gender and age were predictors of the accuracy of pain memory. These results highlight the relevance of pain memory to medical practice and future research.

Use of placebo interventions in primary care in Poland.

OBJECTIVE: The aim of the study was to investigate the behavior, beliefs and attitudes of Polish primary care physicians concerning the use of placebo interventions. SUBJECTS AND METHODS: A total of 220 Polish primary care physicians (internists, specialists in family medicine and pediatricians) were asked to participate in a questionnaire survey and 171 agreed to do so. The questionnaire was a self-report of the behavior, beliefs and attitudes of physicians concerning the use of placebo interventions in clinical practice. The percentages are based on the actual number of respondents to each question. RESULTS: Of 169 respondents, 135 (80%) declared that they used or prescribed placebo interventions, with 20/169 (12%) doing so almost every day, 51/169 (30%) once a week and 44/169 (26%) once a month. The most common placebos used were vitamins (86/135, 66%) and homeopathy (73/135, 56%). Among the participants, 114/129 (84%) reported that the placebos were effective, with only 10/129 (8%) considering them rarely effective; 75/139 (54%) of the physicians considered placebo interventions to be effective only in patients with subjective symptoms, 116/139 (73%) indicated that individual traits of patients were decisive factors in the effectiveness of placebo interventions, and 103/159 (65%) thought that the expectations of patients were of importance. A total of 128/170 (75%) respondents thought that the mechanism of placebo effects was purely psychological. CONCLUSION: The use and prescription of placebo interventions seemed to be very common among Polish primary care physicians studied and they generally had positive attitudes towards their use and effectiveness.

Placebo hypoalgesia induced by operant conditioning: a comparative study on the effects of verbal, token-based, and social rewards and punishers.

Operant conditioning was shown to be a mechanism of placebo hypoalgesia; however, only verbal rewards and punishers were applied in the previous study. We aimed to induce placebo hypoalgesia using more clinically relevant consequences: token-based and social. Participants were divided into three experimental groups (with verbal, social, and token-based rewards and punishers); and two control groups (with and without placebo application). During operant conditioning, participants in the experimental groups received thermal stimuli of equal intensity and were rewarded for reporting lower pain and punished for reporting higher pain compared to their pretest pain levels. The control groups did not receive any consequences. Our results revealed placebo hypoalgesia was induced by operant conditioning only in the experimental groups with social and token-based reinforcement, compared to the control groups. The hypoalgesic effect found in the group that received verbal reinforcement did not differ significantly from the control group with the placebo application. Moreover, expectations about upcoming pain intensity were found to be a mediator, and the number of reinforcers received during conditioning was a predictor of placebo hypoalgesia. These findings highlight the potential benefits of incorporating token-based and social consequences for optimizing treatment outcomes in pain management.