Journal of Personality Disorders, 34(1), 64-87, 2020 © 2020 The Guilford Press 64 From Vita-Salute San Raffaele University, Milan, Italy (R. B., M. C., A. F., C. M.); and San Raffaele Hospital, Milan (C. M.). Roberta Bortolla and Marco Cavicchioli contributed equally to this work. Address correspondence to Cesare Maffei, Vita-Salute San Raffaele University, Via Stamira D’Ancona, 20 20127 Milan, Italy. E-mail: cesare.maffei@hsr.it BORTOLLA ET AL. EMOTIONAL REACTIVITY IN BPD EMOTIONAL REACTIVITY IN BORDERLINE PERSONALITY DISORDER: THEORETICAL CONSIDERATIONS BASED ON A META-ANALYTIC REVIEW OF LABORATORY STUDIES Roberta Bortolla, PhD, Marco Cavicchioli, MSc, Andrea Fossati, MD, PhD, and Cesare Maffei, MD, PhD Emotional hyperreactivity (Linehan, 1993) is the most investigated con- struct in borderline personality disorder (BPD). However, experimental studies revealed mixed results on the topic. Our main objective is to comprehensively summarize the results on emotional reactivity in BPD compared to healthy controls (HCs), using a meta-analytic approach, considering different emotional response systems (physiology, behavior, self- report). We included 31 experimental studies (1,675 subjects). We observed null to small effect sizes for several physiological and behavioral outcomes. Conversely, BPD subjects revealed a moderate to large difference in va- lence attributed to emotional stimuli and a small difference in self-reported arousal. Significant differences in pooled effect sizes were found between self-report and physiological outcomes. Several sources of heterogeneity were explored. In general, the hyperreactivity hypothesis was not support- ed. Additional dysfunctional processes should be taken into consideration to understand BPD emotional responsiveness. Keywords: borderline personality disorder, emotional reactivity, Linehan’s model Borderline personality disorder (BPD) is a severe mental disorder charac- terized by dysfunctions in a wide range of emotional, behavioral, interper- sonal, and cognitive processes (American Psychiatric Association [APA], 2013). One of the most influential clinical theories of BPD development was proposed by Marsha M. Linehan (1993), who hypothesized that the core feature of BPD is represented by emotional dysregulation. In her biosocial model of BPD development, emotional dysregulation was considered the re- sult of repetitive transactions between an individual biological vulnerability and an invalidating environment (Crowell, Beauchaine, & Linehan, 2009).