842 THEMA 23

PAST E X P E R I E N C E AND R E V E R S A L OF PERSPECTIVE

E. PONZO Rome (Italy)

The author describes the results of a research into reversibility of perspective.

MATERIAL OF RESEARCH;

A series of three geometrical designs, alternatively perceptible according to two opposite perspectives (figures with reversible perspective). The three figures, for convenience named A, B and C, were eharacterised by an analogous structure, but by an increasing "complexity" from A to C (the A was the geometrical design of a cube; B and C were designs made by a "combi~aation of cubes").

HYPOTHESES AND

RESULTS OF RESEARCH:

Provided that the subjects had been given instructions to alternate as often as possible the opposite-perspective perceptions and that each reversal was enregistered by the subject by pressing an automatic regis- tration mechanism, the hypotheses of work were the following:

Hypothesis 1:

It was supposed possible to determine a transfer of experience from A to C in the sense of a greater frequence of reversions of C for a prece- dent exercise in reversing A.

This'hypothesis was confirmed by statistical comparisons of the results of two groups of subjects, to the first of which the series was presented in the order A B C, (5 minutes of exercise on A, then 5 minutes on B, and finally 5 minutes on C) whilst to the second group of subjects the series was shown in the order C, A, B (always for the same periods of time).

The two groups were composed of subjects equivalent in age, sex, scholastic and intellectual level at the test D 48.

Hypothesis ll:

It is supposed that the perceptive perlormanee required of the subject

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proves to be less easy to carry out according to the instructions (tending to obtain the maximum possible frequence of reversions) in the more "complex" figures than in the "simpler" ones.

In effect, the frequence of the reversions decre~es (in a statistically significant manner) from A to C, i.e. proceed from the "simpler" figure A, towards the more "complex" figure C.

Hypothesis lIl:

After considering the resulls already published by other authors (obtained under different conditions of research) it was supposed that the capacity to alternate rapidly the perception of the two opposite perspec- tives should be positively correlated with the intellectual level at the test D 4 8 .

This hypothesis has also been confirmed. In particular it results also that the correlation with the intellectual level increases with the increasing complexity of the figures and, therefore, of the perceptive problem-task. That is, it seems that intellectual factors have progressively greater im- portance in the solution of the perceptive problem-task, in proportion to the increase in complexity of the problem.

The detailed data on the methods of research and on the results, as well as the relative theoretical considerations, are in course of publication in the Italian Rivista di Psicologia, I961, LV, 1, pp. 33- -55 .

RE VERS I BLE PERSPECTIVE A N D S A T I A T I O N

L P. HOWARD Durham (England)

There has been much interest recently in the relation between reversible perspective and the process of sat a t ion as postulated in K6hler's theo_ry of the figural-after-effects.

By using ~hree-dimensional, skeletal, rotating wire cubes, we have shown that the time needed to produce the first perspective reversal is easily measured by noting the first apparent change in the direction of rotation. This initial time interval, called here the "satiation t ime" has been found to be about one minute with normal binocular viewing with the cube at a distance of one metre, illuminated against a Mack ground. The subsequent reversals follow with a period of alternation of a few seconds. Using this "satiation time" as a measure we have been abie to answer impo~ant