Additional specific objections The Barnum effect (the tendency to interpret vague statements as specifically meaningful) and the Dr. Fox effect (the tendency for supposed experts to be validated based on likeability rather than actual skill) make it difficult to validate methods of personality testing. These phenomena describe the observation that individuals will give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically for them, but are in fact vague and general enough to apply to a wide range of people. See, for example, Tallent (1958). Non-individualized graphological reports give credence to this criticism. Effect Size: Dean's (1992) primary argument against the use of graphology is that the effect size is too small. Regardless of the validity of handwriting analysis, the research results imply that it is not applicable for any specific individual, but may be applicable to a group. Vagueness: Some important principles of graphology are vague enough to allow significant room for a graphologist to skew interpretations to suit a subject or preconceived conclusion. For example, one of the main concepts in the theory of Ludwig Klages is (or form-level): the overall level of originality, beauty, harmony, style, etc. of a person's handwriting—a quality that, according to Klages, can be perceived but not measured. According to this theory, the same sign has a positive or negative meaning depending on the subject's overall character and personality as revealed by the form-niveau. In practice, this can lead the graphologist to interpret signs positively or negatively depending on whether the subject has high or low social status.Ulfried Geuter, The Professionalization of Psychology in Nazi Germany, pp. 95–96. Cambridge University Press, 1992.
Additional specific objections The Barnum effect (the tendency to interpret vague statements as specifically meaningful) and the Dr. Fox effect (the tendency for supposed experts to be validated based on likeability rather than actual skill) make it difficult to validate methods of personality testing. These phenomena describe the observation that individuals will give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically for them, but are in fact vague and general enough to apply to a wide range of people. See, for example, Tallent (1958). Non-individualized graphological reports give credence to this criticism. Effect Size: Dean's (1992) primary argument against the use of graphology is that the effect size is too small. Regardless of the validity of handwriting analysis, the research results imply that it i,s not applicable for any specific individual but may be applicable to a group. Vagueness: Some important principles of graphology are vague enough to allow significant room for a graphologist to skew interpretations to suit a subject or preconceived conclusion. For example, one of the main concepts in the theory of Ludwig Klages is (or form-level): the overall level of originality, beauty, harmony, style, etc. of a person's handwriting—a quality that, according to Klages, can be perceived but not measured. According to this theory, the same sign has a positive or negative meaning depending on the subject's overall character and personality as revealed by the form-niveau. In practice, this can lead the graphologist to interpret signs positively or negatively depending on whether the subject has high or low social status.Ulfried Geuter, The Professionalization of Psychology in Nazi Germany, pp. 95–96. Cambridge University Press, 1992.