Should FCE be used to identify validity of effort?

Schapmire and colleagues have recently reported a study on ‘consistency of effort’ in this journal [9]. They conclude that pain does not reasonably explain the failure of a statistically based validity criteria for detecting sincerity of effort and that their protocol is appropriate for use in a client population. There are, however, some serious concerns surrounding this paper that we wish to bring forward. These concerns are related to 1) the determinants of variability in motor behavior, especially disability behaviors; 2) the scientific methods used; and 3) the overall tone of the paper. Although many arguments we will make are interrelated, we will explain each of these concerns separately and conclude with a different view on FCE that is, in our opinion, more balanced and supported by current literature.