PLoS One 2010, 5, e14150. No just one element triggers sexual dependancy, but there are assumed to be biological, psychological, and social aspects that lead to the growth of these issues. One of these horses manifests as a vengeful spirit and possesses him. seventy six. Impett, E.A. Strachman, A. Finkel, E.J. Gable, S.L. 75. Muise, A. Impett, E.A. Desmarais, S.