The computational analyses of handwriting in individuals with psychopathic personality disorder

The main aim of the present study was to examine several parameters of handwriting in order to identify the putative specific patterns of writing associated with psychopathic personality disorder. The hypothesis-generating study was carried out with the use of Mann-Whitney U test to compare two groups of prisoners, without p-value, effect size, and confidence intervals for effect size. The handwriting samples were obtained from two groups of individuals: prisoners diagnosed with psychopathic personality (n = 50), prisoners without psychopathic personality disorder (n = 30). Two groups were matched in terms of intellectual level, age, and education. The examined handwriting samples were identical. To examine graphical parameters such as structure, proportions, density, inter-spaces, and impulse, the computer programs GlobalGraf were used. This software is employed by Polish Forensic Association. The inter-group comparisons of graphical parameters have shown there is no significant difference (95% confidence intervals for the effect sizes included 0, or negative numbers) in handwriting between prisoners with psychopathic personality disorder and prisoners without this disorder. Logistic regression has been calculated to show whether any handwriting patterns allow to predict psychopathic personality disorder. Results indicate that participants with psychopathic personality disorder do not exhibit significant motor impairments manifesting in structural, density, topographic, proportions, letter spacing, and impulse features of handwriting. This suggests, contrary to many beliefs related to graphology, that psychopathic personality cannot be identified on the basis of computational forensic examination of handwriting.