It is a neurological feedback showing up unconsciously in the handwriting. In fact, many handwriting analysts have psychologists who submit samples of their patients' writing. They get a quick understanding of the person's personality and fears. This might take months of expensive analysis for the psychologist to learn this. Uses of handwriting analysis include educational entertainment at parties.
Many corporations use it to screen job applicants to find the right person for a particular job.
Lawyers use it to select jurors in order to find people who are logical or people who can be swayed by feelings. The OJ Simpson prosecutors used one of my teachers to select logical people who go by the facts of the case. Of course the other side had those people dismissed because they wanted to use emotion to win the case. Yes, this is called Grapho Therapy. This should only be done under the supervision of a Graphotherapist.