Motivation and expectancy influences in placebo responding: The mediating role of attention

Abstract

Drawing upon research in perception and motivation, the current study proposes a motivation-attention model of placebo in which more motivated persons pay greater attention to placebo-related stimuli, directly influencing placebo response. We manipulated both motivation to respond to placebo and expectations of placebo response in a 2 × 2 design. Participants (N = 152) evaluated a series of placebo pheromones (slightly scented water) of potential romantic dates and made desirability ratings. Consistent with hypotheses, more highly motivated participants demonstrated greater placebo responses, as evidenced by higher desirability ratings of the "pheromone" and greater variability among ratings, when compared to less motivated participants. Moreover, the relation between motivation and placebo response was mediated by attention. Contrary to expectations, we found no effect for expectancy. These findings highlight the importance of motivation and the mediating factor of attention in placebo and support goal-oriented models of placebo.

Differences between experimental and placebo arms in manual therapy trials: a methodological review

“…Previous experiences highly mediate expectancy in various ways: previous effective active treatments showed a higher likelihood to elicit placebo response [ 51 , 52 ], whereas ineffective results attenuate them [ 53 , 54 ], patients with more prolonged treatment exposure showed more significant placebo or nocebo effect [ 53 , 55 ]. Our results showed that 23% of the included studies investigated patients’ previous experiences, but the quasi-totality enrolled naive participants.…”

“…Secondly, we did not take into account some EA items that may influence the placebo response and should be taken into consideration when planning a sham therapy. Particularly the operators’ empathy [ 88 ], the characteristics of the interaction between operators and participants (both verbal [ 51 ]) and nonverbal [ 31 ]) that can modify the patient perception of the therapy believability [ 44 ], including the eventual training of operator aimed at the style of rapport with the patient, and quality of patient-operator interaction [ 20 , 26 ] through a satisfaction questionnaire. Finally, although a protocol similar to Cerritelli et al [ 16 ] was followed, an a priori protocol for this methodological review has not been published.…”

Patients with shoulder pain referred to specialist care; treatment, predictors of pain and disability, emotional distress, main symptoms and sick-leave: a cohort study with a 6-months follow-up

“…They must sign a consent and therefore are motivated to help. This motivation to help makes participants more suggestible to the positive effects of any treatment and could be part of the difference between the present study and the other two Engebretsen et al studies [8]. Motivation could wane with infrequent contact as in the present study where subjects had only 3-5 physiotherapy (PT) sessions over the first weeks and then had no contact until follow-up by mail at six months.…”

Factors that Affect Adolescent Adherence to Mental Health and Psychiatric Treatment: a Systematic Integrative Review of the Literature

“…Among adults, patients who continued to take antidepressant medications as well as those who were switched to placebos had higher mean depression rating scale scores (47). However, more highly motivated patients showed greater responses to placebos as compared with less motivated patients, which highlights the importance of the patient's own level of motivation (48).…”