The Tonic Immobility Scale in Adolescent and Young Adult Rape Victims: Support for Three-Factor Model

Objective: A substantial number of sexual assault victims report experiencing some form of peritraumatic tonic immobility (TI). A self-report questionnaire that is widely used to assess TI retrospectively is the Tonic Immobility Scale (TIS). This study explored the factor structure of the TIS in a clinical sample of adolescent and young adults. Method: The sample comprised 131 female rape victims, aged 13-25, who were referred for specialized trauma-focused treatment. An exploratory factor analysis (EFA) was performed. Results: The EFA showed support for a three-factor model, with factors TI, Fear, and Detachment. Item correlations ranged from .32 to .57 for TI, from .14 to .35 for Fear, and .29 for the two Detachment items. Conclusions: We found support for a three-factor solution distinguishing TI, fear, and detachment, suggesting the need to further develop the TIS with different subscales in varying age groups and clinical samples. Clinical Implication Statement When assessing peritraumatic reactions in adolescent victims of sexual assault using the Tonic Immobility Scale, the present study suggests the use of three subscales. These subscales of Tonic Immobility, Fear, and Detachment may be more appropriate for clinical settings than previously found subscale structures.