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Author(s): Suzanne G. Helfer [sup.1] , Ben Colagiuri [sup.2] , Kate Faasse [sup.3] , Kelly S. Clemens [sup.4] , Fawn Caplandies [sup.4] , Andrew L. Geers [sup.4] Author Affiliations: (1) [...], Attribute framing presents an ethically sound approach for reducing adverse nocebo effects. In past studies, however, attribute framing has not always decreased nocebo effects. The present study used a sham tDCS procedure to induce nocebo headaches to explore factors that may contribute to the efficacy of attribute framing. Participants (N = 174) were randomized to one of three between-subject conditions: a no-headache instruction (control) condition and two conditions in which headaches were described as either 70% likely (negative framing) to occur or 30% unlikely (positive framing) to occur. Results revealed nocebo headaches in both framing conditions, as compared to the control condition. Attribute framing did not influence headache measures recorded during the sham tDCS task, but framing did have a modest influence on one of two headache items completed after the task. Results suggest that attribute framing could have a stronger influence on delayed nocebo effect measures or retrospective symptom reports; a finding that may explain inconsistencies in the existing framing-nocebo effect literature. Exploratory analyses also revealed that low negative affect was associated with stronger nocebo and attribute framing effects, although these effects were found on only a few headache measures. It is concluded that researchers should further investigate the influence of attribute framing on nocebo headaches as a function of both timing and emotional factors.

Illusory causation is a consistent error in human learning inwhich people perceive two unrelated events as being causallyrelated. Causal illusions are greatly increased when the targetoutcome occurs frequently rather than rarely, a characteristicknown as the outcome density bias. Unlike most experimentaldesigns using binary outcomes, real-world problems to whichillusory causation is most applicable (e.g. beliefs aboutineffective health therapies) involve continuous and variableconsequences that are not readily classifiable as the presenceor absence of a salient event. This study used a causallearning task framed as a medical trial to investigate whetheroutcome density effects emerged when using a continuousand variable outcome that appeared on every trial.Experiment 1 compared the effects of using fixed outcomevalues (i.e. consistent low and high magnitudes) versusvariable outcome values (i.e. low and high magnitudesvarying around two means in a bimodal distribution).Experiment 2 compared positively skewed (low density) andnegatively skewed (high density) continuous distributions.These conditions yielded comparable outcome density effects,providing empirical support for the relevance of the outcomedensity bias to real-world situations in which outcomes arenot binary but occur to differing degrees.

Individuals frequently update their beliefs and behaviours based on observation of others' experience. While often adaptive, social learning can contribute to the development of negative health expectations, leading to worsened health outcomes, a phenomenon known as the nocebo effect. This systematic review and meta-analysis examined: whether social learning is sufficient to induce the nocebo effect, how it compares to other forms of induction (classical conditioning and explicit instruction), and factors that influence these effects. The meta-analysis included twenty studies (n = 1388). Social learning showed a medium-large effect size (Hedges' g =.74) relative to no treatment and a to small-medium effect (g =.42) when compared to neutral modelling. The effect of social learning was similar in magnitude to classical conditioning but greater than explicit instruction with a small-medium effect (g =.46). Face-to-face social modelling, longer exposure, higher proportions of female participants and models, and greater observer empathy led to stronger socially-induced nocebo effects. However, further research is essential as only a minority of studies measured important constructs like negative expectancies and state anxiety. Nonetheless, the study highlights social learning as a key pathway for nocebo effects, suggesting it as a target for interventions to reduce the substantial personal and societal burden caused by nocebo effects. [ABSTRACT FROM AUTHOR]

The nocebo effect represents a growing concern in clinical settings. Nocebo effects occur when the treatment context generates negative expectancies that trigger the experience or worsening of negative symptoms beyond any effects attributable to the treatment itself. Despite being identified in a range of outcomes and conditions, from pain to Parkinson's disease, there has not been an attempt to systematically quantify the nocebo effects across health outcomes. The purpose of the present review was thus to systematically review and meta-analyze the nocebo literature to quantify the size of the nocebo effect across outcomes and examine which factors moderate the size of the nocebo effect, including process of induction, treatment type, or health outcome. Method: Systematic searches of PubMed, PychInfo, Medline, and Web of Science identified 130 (n= 8,219) independent eligible studies. To be included, studies had to include both a nocebo and control group/condition, which were compared to isolate the nocebo effect size. Results: Overall, the magnitude of the nocebo effect was medium (g= 0.522) and highly heterogeneous. Two key moderators emerged: health outcome and process of induction. Here, the nocebo effect was medium for most somatic outcomes and affect, with no significant effect on worsening cognitive performance. Further, inducing nocebo effects through instruction in combination with conditioning produced larger nocebo effects. Conclusions: The present review suggests nocebo effects can be reliably induced across somatic health outcomes, and interventions that target the effect of instructions will be of critical importance to reducing the occurrence of nocebo effects. [ABSTRACT FROM AUTHOR]