Sentiment Analysis: applicazione in un dominio psico-forense
Authors: Francesca Guglielmi, Pierpaolo Basile, Antonietta Curci, Giovanni Semeraro (Università di Bari Aldo Moro, 2016)
Topic: Sentiment, Emotion, Irony, Hate

Abstract
This study aims to apply the sentiment analysis to a psycho-forensic context through the analysis of narrative transcriptions related to the crimes committed by violent details. We investigate the presence of psychopathy through the Psychopathic Personality Inventory-Revised (PPI-R). Psychopathy is a personality disorder that is characterized by emotional detection, the lack of empathy and it is often found in the prison population for the brutality of committed crimes. Our study explores possible associations between psychopathy and emotional content present in the narratives. Results show a neutral polarity for both psychopathic and not psychopaths offenders, though it is possible to identify significant emotional characteristics that diverse the narrative transcriptions.

Introduction
Psychopathy is a personality disorder characterized by emotional deficits, antisocial lifestyle, lack of guilt and empathy. In psychopaths the affective coloring that usually serves to differentiate emotional events from neutral ones does not exist to the same extent as other individuals AUTHOR. Psychopaths have a relaxed emotional response to the events they experience and to the people they interact with. The characteristic traits of psychopathy are found in some of the offenders detained AUTHOR, precisely because of the peculiarities related to the violence of the acts experienced by these people AUTHOR. In addition, the emotional callosity, characteristic of the disorder, seems to be associated with a minimalized perception of the emotional experience (positive or negative) of the event experienced, relative both to the moment in which it occurred and to the recall of the event itself AUTHOR. The inability to develop and experience the emotional content of stimuli and events can have consequences on memory capacity and therefore on the possibility of processing and recovering emotional information about the event experienced. Empirical evidence AUTHOR claims that psychopathic people suffer from an emotional deficit that can have an impact on their way of perceiving the memory of events. Some clinicians and researchers argue that psychopaths are generally unable to learn the emotional significance of the events; therefore it is assumed that the stories of psychopathic offenders are devoid of emotional details compared to the narratives of the non-psychopathic offenders AUTHOR. Research in these areas needs to be implemented, in fact in recent years the basic research in cognitive psychology has expanded through the adaptation of procedures, variables and the involvement of other scientific domains, including psycholinguistics. These adaptations make it possible to broaden the knowledge of personality characteristics and their influence on behaviour in diverse contexts, such as the prison, in order to make it possible to implement targeted and suitable intervention programs to support people with such disorders. The present study is the result of these integrations of conceptual domains and research, in this case the sentiment analysis applies, a methodology for the automatic elaboration of the text in order to extract subjective information in a psycho-Forense context. 48 offenders, perpetrators of violent crimes, were asked, through a task of free-recall, to narrate the autobiographical memory of the criminal event committed for which they were convicted, such remembrance was transcribed by the investigators simultaneously to the narration. In addition, each participant was given the Psychopathic Personality Inventory-Revised (PPI-R) AUTHOR to analyze the presence of psychopathy. Each narrative account was subsequently analyzed with the sentiment analysis methodology through an algorithm described in detail in the method paragraph. The results of this analysis are given in the results section.

Conclusion
This work is partially supported by the project "Multilingual Entity Liking', funded by the Region of Puglia with the FutureInResearch program.In this work we have tried to understand if the results produced by an algorithm of sentiment analysis can somehow be associated with psychopathy. In particular, we have analyzed the presence of psychopathy, in a sample of offender held as the characteristic traits of such disorder, emotional detachment, lack of guilt, antisocial lifestyle, it is possible to find them in the offenders held for the peculiarities related to the violence of the experienced acts and the way of life conducted. The results obtained by sentiment analysis were compared with those obtained through the PPI-R test that evaluates the personality traits of the subject through the investigation of those cognitive, emotional and perceptive behaviors and peculiarities that constitute the typical traits of psychopathy. The results obtained through the use of an approach based on the induction of decision trees demonstrate an dependence between the presence of psychopathy and the difference between the maximum positive polarity and the negative polarity identified in the convict's narration. In addition, a correlation has been found between the maximum polarity score and the fearless Dominance factor through the use of statistical tests. The results obtained are encouraging and demonstrate the effectiveness of expanding basic research into cognitive psychology with innovative tools such as sentiment analysis and generally automatic text analysis. The study below, although relevant, is still to be considered preliminary for two reasons: the reduced sample size and the use of fairly simple techniques for the analysis of sentiment.