Investigating Hope and Expectations in Open-Label Placebos
Condition: Pain
Study type: Interventional

Summary: 
      Research has shown that placebo effects contribute substantially to clinical outcomes. Recent
      evidence suggests that placebos remain effective even if they are openly described as
      placebos (so-called Open-Label Placebos). In this study, the investigators examine hope and
      expectations as components of open-label placebos in an experimental study investigating
      pain..
    

Detailed description: 
      A growing body of research has indicated that placebos contribute substantially to clinical
      outcomes. Yet, the implementation of deceptive placebos in clinical practice is incompatible
      with key principles of openness and patient autonomy. However, recent research suggests that
      placebos remain effective even if they openly described as placebos (so-called Open-Label
      Placebos (OLP)), hence questioning the necessity of deception in clinical trials. However,
      research identifying the specific mechanisms underlying OLP is lacking. Therefore, the
      current study aims to examine hope and expectations as components of OLP in pain.

      For this purpose, experimentally induced heat pain is examined. First, all participants
      receive heat pain stimuli and evaluate them. Next, participants are randomly assigned to one
      of four groups: (1) a traditional deceptive placebo (DP) group, which is told that they
      receive an effective analgesic cream, (2) an OLP group inducing hope among the participants
      that the placebo cream could help them tolerating painful stimuli (OLP hope), (3) and OLP
      group raising the expectation that the placebo cream will help participants tolerating heat
      pain (OLP expectation), (4) a control group receiving no cream. Finally, participants receive
      and evaluate heat pain again.
    

Intervention name(s): DP; OLP Hope; OLP Expectation; Placebo cream; Heat pain
Intervention type(s): Other; Other; Other; Other; Other
Intervention description(s): Participants are informed that they are about to receive an effective analgesic cream. They are instructed to apply the cream using a cotton pad.; Participants are informed that they are about to receive an placebo cream. They are told that the cream has no active pharmacological ingredient. Therefore, participants are supposed to evaluate the subjective probability for a positive effect of the cream as rather low. However, using verbal instructions, the investigator aims to induce hope among the participants that the cream could have a positive effect for them because this placebo cream did have a positive among some former participants who were similar to the current participant. The emphasis of this similarity (regarding age and sex) aims to induce a feeling of connectedness to previous participants who reported positive effects of the placebo cream.; Participants are informed that they are about to receive an placebo cream. They are told that the cream has no active pharmacological ingredient. However, participants are told that placebos have been shown to contribute substantially to clinical outcomes such as pain intensity/unpleasantness. This positive effect of placebos is reasoned by explaining learning mechanisms such as classical conditioning. We anticipated that after hearing this instruction, participants would consider it to be likely that the placebo has a positive effect for them.; The participants receive an inert placebo cream (standard basic cream with oil of thyme produced by a local pharmacy).; Participant receive heat pain stimuli using the suprathreshold method of the Thermo Sensory Analyser (TSA-II), a commonly used device to study pain sensation and analgesic effects.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Participants are assigned to one of four experimental groups in parallel for the duration of the study
Masking: Single (Participant)
Primary purpose: Treatment