When a well funded new psi laboratory opened at a university in the late 1970s, James Randi wrote to its director offering, at no charge, to advise on protocol design against conjuring methods. The offer was not taken up. Randi then arranged for two young amateur magicians of his acquaintance, Steve Shaw and Michael Edwards, to apply as subjects, having coached them on how to behave: never claim too much, allow failures, do not perform when the controls are tight, and above all volunteer nothing. They were accepted, tested over an extended period, and reported on as promising. They bent metal, made images appear on sealed film, and produced apparent effects on equipment in sealed containers, all by ordinary means.
Randi sent the laboratory a list of the specific vulnerabilities in its procedures that a conjuror would exploit, without naming his participants. When the two were finally tested under conditions that closed those routes, the effects stopped. Randi disclosed the whole arrangement in 1983. The coaching is the part worth attending to. Randi did not teach them an elaborate act; he taught them restraint. A performer who succeeds every time invites suspicion, and one who volunteers explanations invites testing, so the instruction was to fail often, to say nothing about method, and to decline politely whenever the controls tightened. That is a description of how a good deception survives scrutiny, and it applies well beyond conjuring.