- In humans, the diagnosis of PTSD is made only if an individual exhibits a certain number of symptoms from each of three quite well defined symptom clusters over a certain period of time. Animal behavioral studies, however, have generally tended to overlook this aspect and have commonly regarded the entire group of animals subjected to certain study conditions as homogeneous. Thus, in an attempt to develop animal models of long-term chronic behavioral responses to stress (i.e. PTSD) in a comparable manner to human diagnosis, we applied cut-off inclusion/exclusion criteria to behavioral data for a cohort of animals exposed to a stress paradigm. This grouped them as behaviorally affected or unaffected by the stress. This model takes into account the variability in degree of the individual’s response to the stress paradigm, thereby modeling the fact that not all humans exposed to traumatic stress respond with affective disorder. This article will present and discuss findings from a series of studies employing a model of individual behavioral response classification. This article will discuss the concept of the model and its background and present a selection of studies employing and examining the model, alongside the underlying translational rationale of each. This article is part of a Special Issue entitled ‘Post-Traumatic Stress Disorder’.