A multi-sample investigation of psychological flexibility processes and reactive and proactive functions of aggression

Both theory and empirical research support the application of the psychological flexibility model to understanding aggressive behavior. However, methodological limitations persist, as studies have generally relied upon a single measure of psychological inflexibility, and measures of aggression typically fail to differentiate aggressive behavior based on function. This limits our ability to understand how specific dimensions of psychological (in)flexibility relate to functional differences in aggression. To extend this line of research, the primary aim of this study was to examine the associations between proactive and reactive aggression, and multiple measures of psychological (in)flexibility processes, across three samples: one undergraduate (N = 116) and two online community samples (N = 262 and N = 317). Further, we examined the unique contribution of psychological (in)flexibility processes in the prediction of aggression, over and above negative affect-related variables. Proactive and reactive aggression was assessed across all samples, with individual samples also responding to various measures of anger, negative affect, negative urgency, experiential avoidance, cognitive fusion, valued living, or a multidimensional measure of psychological flexibility. Correlational and regression analyses revealed that inflexibility processes were generally associated with reactive aggression, but more inconsistent associations were found with proactive aggression in multivariable models. Flexibility processes, on the other hand, exhibited inconsistent and sometimes unexpected associations with aggression. The psychological flexibility model appears useful in understanding different functions of aggressive behavior, however additional research is necessary to clarify the nature of discrepancies within and between samples.