Pseudotaxonicity in MAMBAC and MAXCOV analyses of rating-scale data: turning continua into classes by manipulating observer's expectations

Taxometric procedures such as mean above minus below a cut and maximum covariance can determine whether a trait is distributed as a discrete latent class. These methods have been used to infer taxonic structure in several personality and psychopathology constructs, often from analyses of rating scale data. This is problematic given (a) well established biases in ratings, (b) the human tendency to think categorically, and (c) implicit typological models of personality and psychopathology among expert raters. Using an experimental method in which the cognitive sets of raters were manipulated as dimensional versus categorical, it is demonstrated that pseudotaxonicity can be created readily with rating scale measures. This suggests that researchers avoid an exclusive reliance on rating scales when conducting taxometrics investigations.