Is schizotypy taxonic? Response to Beauchaine, Lenzenweger, and Waller

Beauchaine, Lenzenweger, and Waller (2008) criticize our taxometric study of schizotypy (Rawlings, Williams, Haslam, & Claridge, in press) on a variety of methodological and philosophical grounds. We argue that their critique selectively applies more stringent standards to our work than to studies supporting their view that schizotypy is taxonic (i.e., categorical). Many of their criticisms apply at least equally to existing studies that offer support for a schizotypy taxon, and these studies are vulnerable to biases favouring taxonic conclusions that were controlled for in our study. Contrary to their criticisms, we did not claim to have disconfirmed previous taxonic findings about schizotypy, and our findings positively support dimensional models of schizotypy rather than merely being null results. Similarly, our findings are not artefacts of the sampling or measurement decisions that they question. Even well-replicated taxometric findings are not immune to empirical challenge, and evaluation of such challenges must be even-handed.