Lilienfeld and his colleagues suggest six main causes of practitioner resistance.
Practitioners believe they can rely on their own intuitions. They may fail to see that a change in a person is not because of therapy/training. People may change not as a result of the therapy/training but rather because of factors such as the placebo effect (improvement as a result of the expectation of improvement); spontaneous remission (people get better on their own over time); effort justification (people justify their commitment to the training regime by saying they are better); and multiple treatment interference (other things they are doing are working, not the therapy/training).
People hold passionate beliefs based on theories that have been demonstrated to be wrong. These beliefs can encourage people to dismiss evidence because it goes against their deeply held belief system.
. . . generalising from single-case studies to groups, but refusing to apply group probabilities to individuals. “Aah,” the coach says, “everyone is different” — often a let-out.
Surely it is up to practitioners to show (beyond all reasonable doubt) that their training works rather than for the critics to collect evidence that practitioners’ claims are invalid. So the trainers attack the sceptics’ evidence rather than providing their own.