Treatments, randomization and blinding
nausea
Participants in the treatment groups received a standardized positive verbal suggestion of nausea improvement (for details, see Aichner, et al. The recruited women consecutively received a participant number from a list. Before the start of the study, an independent researcher assigned all participant numbers in advance to the respective experimental conditions using the random sequence generator implemented in Microsoft Excel. For each participant number, the independent researcher prepared two sealed envelopes with respective group assignment information. The first envelope assigned participant numbers to the “stress” or “non-stress” condition and was opened by the person conducting these tasks. After completion of the task, the main experimenter entered the room and opened the second envelope containing the treatment assignment information, thus remaining blinded regarding the stress or non-stress condition. Participants in the treatment groups were blinded regarding the type of treatment (placebo or active treatment), whereas participants in the no treatment control group were necessarily unblinded.