Year of Award


Document Type


Degree Type

Doctor of Philosophy (PhD)

Degree Name

Clinical Psychology

Department or School/College

Department of Psychology

Committee Chair

Christine Fiore

Commitee Members

Alison Pepper, Allen Szalda-Petree, Caitlin Martin-Wagar, Elizabeth Hubble


coping, outcomes, sexual assault, tonic immobility, trauma


University of Montana


Tonic immobility (TI), a temporary, involuntary state of paralysis marked by motor inhibition and vocal suppression, has been a well-documented occurrence among animals. Humans also experience TI, which has previously been referred to as trauma- or rape-induced paralysis and freezing. TI among survivors of sexual assault has been associated with greater PTSD and increased risk of depression. Existing studies have not adequately explored additional posttraumatic outcomes of TI beyond PTSD diagnostic criteria, nor has prior research sufficiently tested the mechanistic relationship between TI and PTSD. The objective of the current study was to integrate and expand upon prior research regarding the impact of TI on sexual assault survivors. Quantitative methods examined several cognitive, emotional, behavioral, and social posttraumatic outcome variables among university college students who experienced sexual violence to understand how TI impacts these outcome variables and whether they help explain the mechanisms of the TI-PTSD association. Participants were a subset of university students who volunteered to complete an additional component of the campus-wide Safe Campus Survey. Analyses revealed that TI was significantly associated with and a stable predictor of negative posttraumatic cognitions, guilt, self-blame, negative social reactions, lower perceived social support, maladaptive coping, and trauma symptomology even after controlling for sexual assault severity, recency of sexual assault, and revictimization. Mediation and moderated mediation analyses tested the indirect and conditional indirect effects of the variables on the TI-PTSD relationship. The relation between TI and trauma symptomology was partially mediated by negative posttraumatic cognitions, guilt, self-blame, and maladaptive coping. Negative social reactions did not significantly moderate the direct and indirect relationship between TI and trauma symptomology through negative posttraumatic cognitions. TI and negative social reactions were shown to be significant predictors of negative posttraumatic cognitions and trauma symptomology, lending support to significant main effects rather than significant moderation effects. Results inform trauma response theories and reveal clinically relevant information that could help shape targeted therapeutic interventions and supportive services for survivors who experience TI during sexual assault. Results also contribute to efforts to correct societal misconceptions about trauma responses and decrease victim-blaming attitudes and negative social reactions that harm survivors.



© Copyright 2023 Nora Grace Halverson