Problem: When we carry out an action which we do not master, we often experience a seperation of action and surface of action, or an inconcurrence of action intended and action really done. And, in such cases we feel, as if our own bodies-especially hands or legs-lay outside of the limits (region) of our control. Our study intends to research the general characteristics of such a state of action, under a special but compact condition, namely under the torsion of opto-motoric system. Here, we report the preliminary part of experiments.
Arrangement For this purpose a trapezoidal prism is used; by means of it we can get torsions of usual opto-motoric system in various manners. We use four typical cases of such torsions (see Fig. II in the Japanese text). In every cases, subjects (20 men) are instructed to draw a straight line on a Taper from the point o to the other point +, seeing through the prism.
Results: The following is the summary of results obtained from these preliminary experiments.
(1) In most cases, initial movements start on the line of the optical direction of o 4, but the lie of initial movements does not alwayA coincide with the optical lie of initial movements, except few cases of every subject, and then, some start from o towards + and others start opposite to. These facts seem to show that the optical field in these conditions rules the action in respect more of the line of direction of movement than of its lie, and such a character of optical field seems to be more similar to the character of geometrical space than that of dynamical.
(2) We can classify the processes of action which follow the initial movement in three types: namely controlled action (see Fig. V 4 in the Japanese text), searching action (see Fig. V 6 in the Japanese text), and confused action (see Fig. IX 1 in the Japanese text).
The torsions of opto-motoric system, by which the optical direction and the objective direction cross ,each other at right angles and so the visual space and the'manual space' (the space in which the hand moves) in respects of both line of direction and lie differ with each other (see Fig. II b and Fig. II d in the Japanese text), cause confused action more than the torsions of other types by which both fields at least in respect of line of direction coincide with each other (see Fig. II a and c in the Japanese text).
In confused action, movements are fragmentary, trembling, and impulsive, and the surface of action lies outside of field of person.
(3) When the course of movement begins to swerve, the tendency to come back on the 'fictive line' of+ often appears, especially in the fi rst stadium of practice. However, in the course of practice, this tendency becomes more and more weak and at last is replaced by direct movement towards+This seems to show that the force of+grows stronger as the action differentiates. Also the fact that the tendency to come back on the line of+is much more weak in the controlled action than in other actions confirms this interpretation.
(4) We find sometimes confused action break out near the end of controlled action. Conditions of such 'break-out' are not yet clear in these experiments.