Participants’ knowledge about placebos
| Item | Correct answer | Total % correct (n) | Read/heard about placebos (n=143)† % correct (n) | Not read/heard about placebos (n=64)† % correct (n) |
| A pill with aspirin in it is called a ‘placebo’ pill | False | 98.1% (206) | 98.6% (141) | 96.9% (62) |
| The placebo effect can work because of people’s expectations | True | 95.2% (200) | 99.3% (142) | 85.9% (55)** |
| Placebo treatments are only effective for people who are not very intelligent | False | 96.7% (203) | 97.9% (140) | 93.8% (60) |
| Placebo treatments can help to treat pain conditions | True | 79.5% (167) | 82.5% (118) | 71.9% (46) |
| Placebo treatments do not help to relieve any medical symptoms | False | 72.9% (153) | 76.2% (109) | 65.6% (42) |
| Placebo pain treatments only relieve imaginary pain (ie, pain that was not real in the first place) | False | 85.2% (179) | 89.5% (128) | 75.0% (48)** |
| A pill with no medicine in it is called a ‘placebo’ pill | True | 91.9% (193) | 97.9% (140) | 78.1% (50)** |
| The placebo effect can work because of conditioning | True | 74.3% (156) | 74.8% (107) | 73.4% (47) |
| Real changes in the brain can occur when you receive a placebo (such as the release of chemicals called opioids) | True | 83.8% (176) | 88.1% (126) | 73.4% (47)* |
| Placebo effects are imaginary and have no real physical effects on our body | False | 81.0% (170) | 83.2% (119) | 76.6% (49) |
| Placebo effects only occur in experiments and research trials | False | 86.2% (181) | 90.2% (129) | 76.6% (49)** |
| A placebo pill can have side effects | True | 31.9% (67) | 34.3% (49) | 28.1% (18) |
| The placebo effect can help us to get better during normal medical treatments | True | 79.5% (167) | 83.9% (120) | 68.8% (44)* |
| The colour of a placebo pill can change how effective it is | True | 55.2% (116) | 60.1% (86) | 43.8% (28)* |
| Placebo treatments are only effective for people who lie about their symptoms | False | 96.7% (203) | 99.3% (142) | 90.6% (58)** |
*p<0.05, **p<0.01, significant χ2.
↵†Three participants did not specify whether they had previously read or heard about placebos.