A prior investigation found that individuals low in optimism are more likely to follow a negative placebo (nocebo) expectation. The present study tested the hypothesis that individuals high in optimism are more likely to follow a positive placebo expectation.
Individuals (N=56) varying in their level of optimism were randomly assigned to one of three conditions. In the first condition, participants were given the expectation that a placebo sleep treatment would improve their sleep quality (placebo expectation condition). In the second condition, participants engaged in the same sleep treatment activity but were not given the positive placebo expectation (treatment control condition). Finally, a third group did not receive the positive placebo expectation and also did not engage in the placebo sleep treatment (no-placebo control condition).
Optimism was positively associated with better sleep quality in the placebo expectation condition (r=.48, P<.05). Optimism scores were not associated with better sleep quality in either the treatment control condition (r=-.17, P=.46) or the no-placebo control condition (r=-.24, P=.35).
Dispositional optimism relates to placebo responding. This relationship, however, is not manifested in a simple increase or decrease in all types of placebo responding. Rather, it appears that, as optimism increases, response to the positive placebo expectation increases, whereas response to nocebo expectation decreases. It is recommended that future research on personality and placebo effects consider the interaction between situational and dispositional variables.
"For example, extraversion predicted placebo induced improvements in irritable bowel syndrome symptoms only in the presence of an empathic practitioner . Empathic concern was only related to placebo analgesic responses in a social learning condition that involved a confederate , and the link between optimism and responding may only eventuate in positively valenced contexts  . "
[Show abstract][Hide abstract] ABSTRACT: Aim: To identify personality traits related to placebo responding outside the context of pain. Methods. Sixty three healthy volunteers completed the study. Personality traits were measured online one week prior to a laboratory session in which two psychosocial stress tests were administered. Prior to the second test, the placebo group received an intranasal spray of ‘serotonin’ (placebo) with the suggestion it would enhance recovery. Subjective stress, heart rate and heart rate variability were measured. Self reported and physiological responses to the placebo suggestion were assessed against personality variables.
Results. Placebo effects were demonstrated in both self reported and physiological stress metrics. Lower optimism and less empathic concern predicted greater perceived benefits from the placebo treatment; and lower drive, fun, and sensation seeking were related to a greater physiological response to the manipulation. Multivariate analyses revealed lower optimism and behavioural drive to be predictive of responding to the placebo manipulation.
Conclusion. Findings are in contrast with prior work in pain paradigms which found higher levels of the same traits to be related to greater placebo analgesic responses. A cluster of traits characterised by behavioural drive, extraversion, optimism and novelty or fun seeking appears to be germane to placebo responsiveness, but contextual stimuli may generate different patterns of responding. A new conceptualisation of placebo responsiveness may be useful. Rather than a ‘placebo personality’ it may be that responsiveness is better typified by a two faceted transactional model, in which different personality facets respond to different contextual contingencies.
Journal of Psychosomatic Research 04/2014; 76(5). DOI:10.1016/j.jpsychores.2014.02.011 · 2.74 Impact Factor
"The individual psychological characteristics of suggestibility, neuroticism, and social desirability were additionally assessed, because these characteristics may affect the magnitude of nocebo and placebo effects   . Therefore, the following validated questionnaires investigating individual psychological characteristics had been filled out within 1 week before the testing took place. "
[Show abstract][Hide abstract] ABSTRACT: Physical complaints, such as pain, can be effectively reduced by placebo effects through induction of positive expectations, or increased by nocebo effects through induction of negative expectations. In the present study, verbally induced nocebo and placebo effects on itch were experimentally investigated for the first time. In part 1, the role of verbal suggestions in inducing nocebo effects on itch and pain was investigated. All subjects received the same somatosensory quantitative sensory testing stimuli, that is, mechanical and electrical stimuli and application of histamine, and verbal suggestions to manipulate expectations regarding the stimuli. The suggestions were designed to produce either high expectations for itch (itch nocebo) or pain (pain nocebo) or low expectations for itch (itch nocebo control) or pain (pain nocebo control). Results showed that high itch and pain expectations resulted in higher levels of itch and pain, respectively. When comparing nocebo effects, induced by verbal suggestions, results were more pronounced for itch than for pain. In part 2, verbal suggestions designed to produce a placebo effect on itch (itch placebo) or pain (pain placebo), or neutral suggestions (itch placebo control and pain placebo control) were given regarding a second application of histamine and compared with the first application applied in part 1. Results of placebo effects only showed a significantly larger decrease in itch in the itch placebo condition than in the pain placebo condition. In conclusion, we showed for the first time that nocebo and possibly placebo responses can be induced on itch by verbal suggestions.
"Az énhatékonyság abban való hit, hogy képesek vagyunk végrehajtani valamit. Korábbi kutatási eredmények alapján (Geers, Helfer, Kosbab, Weiland és Landry, 2005; Geers, Kosbab, Helfer, Weiland és Wellman, 2007) a szerzők szerint pozitív kapcsolat van a placebo válaszkészség és az optimizmus között (Buckalew és Ross, 1981; Scheier és Carver, 1985; Walach, Schmidt, Dirhold és Nosch, 2002). "
[Show abstract][Hide abstract] ABSTRACT: A brief theoretical discussion of the placebo effect and of some methodological issues of the measurement of it are followed by a narrative review based on the results of our earlier metaanlysis of fourteen published research on the investigation of placebo effect in sports and exercise. Various factors (e.g. personality factors, perceptual characteristics of the applied substance or treatment) of placebo-effect effecting performance in sports and relevant research are also addressed. Absztrakt A placebo-hatás rövid elméleti áttekintését, valamint a placebo-hatás mérésének néhány módszertani problematikájának bemutatását korábbi metaanalízisünkön alapuló, különböző sportokban végzett placebo-hatás vizsgálatok narratív összefoglalója követi. A sportban megfigyelhető placebo-hatás különböző, a teljesítményt is befolyásoló összetevőit (pl. személyiség, az alkalmazott szer perceptuális tulajdonságai) vizsgáló kutatásokat is ismertetünk.
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