[AI] The mental state just described is probably essentially the same as that of the spiritualistic "mediums" when they are occupied with table-rapping and table-moving. In both cases concentration is very intense,——in other words, the field of attention is limited. We saw that this state not only favors the tendency toward involuntary movement, but on account of the absorption of the individual's attention by a certain limited content, the person will be unaware of the voluntary movements as they occur. And we are not necessarily here dealing with neurasthenic, hysteric, or other diseased nervous conditions. In the case of table-rapping there are movements of the hands, in our case there are those of the head. Our head, balanced as it is upon the cervical vertebral column, is continually in a state of unstable equilibrium and therefore peculiarly susceptible to movement-impulses of every kind. But I could induce not only movements of the head, but also of the arms and legs, and this by having the subject assume a posture which enabled him to hold arms or legs in as unstable a position as possible. He might stretch out his legs horizontally before him, or he could raise them vertically upward as in the hand-stand in gymnastic work. An extract from a treatise by Count A. de Gasparin,[94] which appeared about the middle of the last century, may serve to show how close the correspondence between the two processes, that of getting the table to rap and that of causing Hans to respond, really is. The report of this writer, based upon the detailed record of his tests in table-moving and table-rapping, closely parallels in many minute
details the observations which were made in the course of our experimentation with Hans. The case is all the more remarkable when we bear in mind that this writer did not seek the cause of the phenomena, as we did, in involuntary movements, but thrusting aside this explanation, he posited the cause in the agency of some mysterious fluid. It may not be amiss to say that this as well as most other references were consulted after the present experiments and introspections had been completed. Of the page references preceding the following citations, the first always refers to the page in the French original, and the other, enclosed in brackets, to the parallel passage in the present monograph.
P. 49 [31]. Some questioners are especially suitable ("experimentateurs hors ligne"), but in their absence, other persons may also operate successfully ("le succès, quoique moins brillant alors, n'est pas impossible.")
P. 25 [229]. But even the most suitable questioners do not always succeed equally well ("les plus sûrs d'eux-mêmes ne réussissaient pas également tous les jours.")
P. 42 [151]. When the questioner is in any way indisposed, the measure of success is also less.
P. 91 & 87 [150]. The Questioner must first get into the sweep of things ("en train"), and once he has done so, all interruption whatsoever must be avoided.
P. 91 [93]. Unless there is sufficient tension on the part of the questioner, the test will fail. ("La volonté est-elle absente, rien ne bouge.")
P. 210 [93]. When there is too low a degree of tension, then too great a number will be tapped ("si votre volonté ne les [les tables] arrête pas au moment où se termine le chiffre pensé, elles continueront indéfiniment.")
P. 31 [93]. But too great concentration of attention will also produce failure ("s'il n'arrivait ... de désirer trop fortement le succès et de m'impatienter en cas de retard, je n'avais plus aucune action sur la table.")
P. 36 [151]. If the proper mood ("entrain habituel") is wanting and the tests are unsuccessful, it is best not to attempt some new and difficult experiment, but to turn to some that are simpler and more entertaining ("La table obéissait mal; les coups étaient frappés mollement et comme à regret.... Alors nous avons pris un parti dont nous nous sommes bien trouvés; nous avons persévéré, et persévéré gaiement; ... nous avons écarté la pensée des tentatives nouvelles, et insisté sur les opérations aisées et amusantes. Après un certain temps les dispositions étaient changées, la table bondissait et attendait à peine nos commandements.")