Tarrier et al (Reference Tarrier, Sommerfield and Pilgrim1999) report no significant difference in outcome for patients with post-traumatic stress disorder who received either imaginal exposure or cognitive therapy. They conclude that “ clinical benefits for both treatments were maintained”.

In the absence of a control group such a conclusion is not warranted. Their findings are open to a number of interpretations, including significant improvement in spite of harmful effects of either or both treatments - supposing, that is, that there were two treatments. Meanwhile, their suggestion that more research is needed does merit support.