017 Citation: Perrotta G, Eleuteri S. “Perrotta Ego Hypertrophy Investigation Questionnaire (PEHI-Q)”: Development, Regulation, and Validation of a Psychometric Tool to Investigate the Clinical Aspects of Ego Hypertrophy. Open J Trauma. 2025;9(1):017-026. Available from: https://dx.doi.org/10.17352/ojt.000049 https://dx.doi.org/10.17352/ojt DOI: 2640-7949 ISSN: CLINICAL GROUP Abstract Introduction: In literature, the concept of egoism is associated with the psychic ego instance under hypertrophic conditions; however, there are currently no psychometric instruments capable of distinguishing the functional form (self-love) from its dysfunctional variants (infantilism, egocentrism, and narcissism). Aim: A validation study was conducted to assess whether the proposed psychometric instrument can reliably and validly investigate the efficiency of the ego psychic instance in relation to the hypotheses of hegonic hypertrophy. Materials and methods: A new psychometric instrument was developed for administration to a selected clinical population (144 males/females, aged 16-70 years, M: 40.2, SD: 16.4) and was compared with a previously used instrument (Narcissistic Personality Inventory, NPI). This comparison aimed to investigate the efficacy of the ego psychic instance, clinically assess the level of subjective egoism, and ultimately validate the new instrument. A control group with similar characteristics was selected. Results: Statistical analysis revealed that the psychometric test possesses a well-defined and stable construct, with the variables accurately represented and positively correlated with another already validated construct. Conclusions: The Perrotta Ego Hypertrophy Investigation Questionnaire, first edition (PEHI-Q), is a valid, efficient, and stable psychometric tool for examining the clinical aspects of ego hypertrophy. Research Article “Perrotta Ego Hypertrophy Investigation Questionnaire (PEHI-Q)”: Development, Regulation, and Validation of a Psychometric Tool to Investigate the Clinical Aspects of Ego Hypertrophy Giulio Perrotta* and Stefano Eleuteri Department of Psychology, Universitas Mercatorum, Rome, Italy Received: 20 May, 2025 Accepted: 10 June, 2025 Published: 11 June, 2025 *Corresponding author: Giulio Perrotta, Department of Psychology, Universitas Mercatorum, Rome, Italy, E-mail: info@giulioperrotta.com ORCiD: https://orcid.org/0000-0003-0229-5562 Keywords: Ego hypertrophy; Ego; Narcissism; Egocen- trism; Infantilism; Egoism Copyright License: © 2025 Perrotta G, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduc- tion in any medium, provided the original author and source are credited. https://www.clinsurggroup.us Abbreviations PEHI-Q: Perrotta Ego Hypertrophy Investigation Questionnaire; PEHI-T: Perrotta Ego Hypertrophy Investigation Theory; PEHI-M: Perrotta Ego Hypertrophy Investigation Model; NPI: Narcissistic Personality Inventory; PNI: Pathological Narcissism Inventory; NGS: Narcissistic Grandiosity Scale; IES: Interpersonal Exploitativeness Scale; PES: Psychological Entitlement Scale; APA: American Psychiatric Association Background The construct of selfishness in the literature is extensively studied but only linked to the concept of narcissism when the topic under consideration involves entrepreneurship, morality, ethics, and competition [1-5]. Conversely, no research addresses functional and dysfunctional forms of egoism from a clinical perspective, except for neuroscientific issues related to the dimensions of grandiosity, perfectionism, dominance, and self-confidence [6,7]. However, all these studies reference the broader concept of “Ego,” understood as