When psychics and miracle workers are tested in laboratory conditions and nothing happens, we are told that the sceptical minds of the investigators are the problem. This can be used to claim that the experiment has shown that such powers exist after all, but just not in the way expected. Or it can be used to claim that there is, at least, no disproof ever.
That clearly means the investigators have psychic powers themselves and block the other psychics. Now, people who are tested must have reputedly remarkable abilities, so we are being asked to believe that a sceptic has enough power to block them. If we all have the same powers, is there any point in testing any individuals as if they are something special? Aren’t we told that the powers are yours, so you have to use them, and they don’t work without your consent? If they had a mind of their own, there would be no point in mediumship demonstrations or tests in the laboratory. The implication is that the sceptics are deliberately blocking the exercise of the powers that the subjects have. Surely, if they were open-minded and did not care what the truth was one way or the other, they could not stop the magic. There are paranormal supporters who want to blame open-mindedness for destroying tests and experiments! Let that be a warning concerning how many beliefs are really a threat to science and truth.
Why just the lab? Many do, in fact, say that you could be using your power to heal, and somebody who does not believe you can do it will stop your healing and maybe be the main cause of your death. John wants his son to recover from a terminal illness, and the son is desperately trying to wield paranormal abilities to at least reduce the danger. There is a sceptic in the house. That person would need to hate the boy to be able to block or weaken his powers. Do we want to go back to the days when witches were blamed for shipwrecks and plagues? If we mistrust people over our adherence to paranormal beliefs, then there is no real benefit to them. Trust is healthy.
The laying of blame on the sceptics—usually by mystics who ironically claim to be non-judgemental—is extremely important. It shows that the mystic, even if powers could be identified, is not an honest person for trying to gaslight and undermine the investigation if it should show there is nothing otherworldly going on. Their ideas are an implicit and potential attack on the integrity of scientific researchers.
FINALLY
Claims that sceptics - or even believers who have developed doubts - or people praying against psychic demonstrations - might be “blocking” the psychic powers of test subjects by virtue of their own abilities are rife. The idea is that they use powers to defeat those of the person being tested. They may be biased or dishonest. This is an ad hominem attack. But it shows where affirming the likelihood of supernormal powers can lead. It is not surprising. The attack is a dismissal of science's ability to objectively assess the situation.
APPENDIX:
We cannot interview the apostles or conduct forensic tests on the empty tomb of Jesus. Similarly, there is only a single source—the Bible—that claims Moses parted the Red Sea. Relying solely on one testimony, especially for extraordinary events, requires careful scrutiny. While it may seem unfair to apply modern standards of evidence to ancient claims, it is reasonable to expect clarity if God intends to make a truth known in a world prone to error. The absence of modern investigative methods doesn't invalidate the claims themselves, but it does highlight a lack of independent corroboration. Hearsay alone, without substantial supporting evidence, is insufficient to substantiate a major supernatural claim.