Subjective measures
OLP, ’
SECONDARY
After each of the tasks described above, participants were asked to rate their cognitive performance using computerized Subsequently, we administered five standardized questionnaires, which were preregistered as secondary outcomes, and measured different psychological parameters at both time points: The Lastly, at the Test session, participants were asked to indicate their satisfaction with their group allocation. The question ‘Are you satisfied with your group allocation (placebo or control group)?’ was answered on a VAS from 0 to 100 with the anchors ‘no, not at all’ and ‘yes, absolutely’. They were also asked in a yes-or-no question, whether they would have preferred to be in the other group. The OLP group was then asked a few questions about their adherence to the placebo intake (how regularly they took the placebo capsules, whether they thought the placebo intake improved aspects such as concentration, “mental freshness”, mood, well-being, sleep, and bodily complaints, whether they would recommend the OLP intake to friends or family and whether they would like to continue the OLP intake; each on a VAS from 0 to 100 with the anchors ‘no, not at all’ and ‘yes, very’).