Predictors of tonic immobility during traumatic events

Abstract

Tonic immobility (TI) is a possible reaction to danger that is facilitated by intense fear, physical restraint and perceived inability to escape. Other variables that could affect TI, such as the type and characteristics of traumatic events and personal characteristics have been little or no studied. The present study evaluated the power of these variables to predict TI in a sample of 273 college students who had experienced at least one traumatic event. Of the sample, 7.7% and 13.2% responded with TI according to the two stricter definitions adopted. Most of the variables were significantly associated with TI in univariate analyses. However, in a multiple regression analysis, only certain features of the events (occurrence of physical/sexual abuse, number of different types of events experienced) and certain reactions to them (perception of how traumatic were the events, severe fear response) were significant predictors of TI. Since these predictors explained only 25% of the variance, the influence of other variables -such as neuroticism, negative affectivity and perceived lack of personal control or resources to cope with traumatic events- should be investigated.