The authors define the concepts of attention, concentration and hypnosis. Starting from these theses they examine the possible existence of a continuum of states of consciousness, from wakefulness to the so-called hypnosis, with an increasing number of correlations of neurophysiological plasticity. The authors point out that, in those cases in which the requirements needed for the hypnotic phenomenon to take place are lacking, it is possible to exploit the patient's 'concentration' by using a kind of ideoplastia which goes with it. The final question is whether or not the concepts of concentration and hypnosis are synonymous - whether or not concentration is hypnosis or vice versa. The authors offer some personal and original reflections on these questions.