• Clinical research indicates a tendency to compulsive repetitions of traumatic experiences. Such phenomena have not been studied experimentally and so the generality of the tendency has been uncertain. With development of operational definitions and content analysis techniques, it was possible to quantify and examine intrusive and stimulus-repetitive thought in a series of experiments with controlled variations in subject selection, stimuli, demand set, and context.
Comparison of data across experiments indicates a tendency toward intrusive and stimulus-repetitive thought that is not restricted to "traumas" or a few predisposed individuals. Intrusive and repetitive thought appears to be a general stress-response tendency seen in a large proportion of persons after even mild to moderately stressful events. It is concluded that the intrusive repetitions observed clinically are extreme forms of this general stress-response tendency.
Mardi J. Horowitz. Intrusive and Repetitive Thoughts After Experimental StressA Summary. Arch Gen Psychiatry. 1975;32(11):1457–1463. doi:10.1001/archpsyc.1975.01760290125015