Perception of Physical Things

We must start with the simplest appearances, but paradoxically the simplest appearances are not the easiest to observe. Generally one perceives that the mountain is large and covered with white snow without noticing its apparent smallness or its reddish hue. To become aware of the latter the direction of attention must be changed in a subtle way. It must be diverted from the mountain and directed to sensuous presentations in themselves. Neverthe less from such appearances we must start though not in their artificial form. What is artificial is the restriction of attention to isolated data in the field, and to certain of their characters in a similar isolation. There is no such complete restriction either in primitive or in normal developed perception. Our original apprehension is of a complex whole all the ingredients of which co-operate, without being individually apprehended, to deter mine the judgments of perception. The colour constituent of the sense-presentation largely determines the colour attributed to the physical object, size and shape in the sense-presentation, size and shape in the object but these factors do not operate indepen dently of each other. Ellipticity, for example, in the sense appearance of a plate combined with differences in sensible depth in different parts of the ellipse jointly determine the judgment that the plate is round, and similar considerations apply to perceptual judgments of colour and size.

Such joint determination is not wholly acquired. Moreover, not only is a given character, say A, as applied to a physical ob ject, jointly determined by a combination of characters, say in the particular sensation, but the characters of a conjunc tion of distinct sense-presentations, say P', Q' and R', may also determine the character assigned to a particular physical object, say P, which corresponds to only one of them. This is exempli fied by the laws of confluence and contrast.

Appearance and Reality.

Sensuous presentations, which practically may be sensibly experienced without being discrimi nated, singly or jointly determining our judgments of perception. The problem is to assign to these judgments their sensory condi tions. We are thus concerned not with the evolution of percep tion out of bare sensation but with two lines of parallel and correlated growth. Knowledge of sense-presentation is not prior to knowledge of physical things. The most that we can say is that originally there is no explicit distinction between judgments with regard to such presentations and judgments with regard to physical things. The occurrence of a sense impression having the attributes a, b, c, occasion the immediate awareness that there is something to which these properties belong. This object is thought of neither as "my sensation" nor as "that physical thing." The distinction between sense-presentations as such and physical objects, as well as the connected distinction between appearance and reality, depends upon experienced contradictions, and more especially upon the thwarting of conative activity.

The child before he reflects upon the illusions of sense attempts to grasp the moon. Disappointed expectations of this kind imply a faulty objective reference. The awareness of contradiction depends for its possibility upon judgment transcending the limits of actual sense-presentation, it pre-supposes in particular the reference of different sense to an identical physical thing. Only in so far as that which visually is elliptical is regarded as identical in shape with that which to touch feels round can contradiction arise. But the reference of characters of separate sensation to a single thing cannot be determined on the basis of the particular sensum considered in isolation. It depends more particularly upon concomitant variation between the sense-pres entations involved and between these and the experience in volved in practical experiment.

The experience of contradiction arises when conditions largely favour, but do not wholly sustain the judgment of identification. But in such cases contradiction is never complete and absolute.

Where there is no approximation to concomitant variation, no synthesis, and hence no contradiction, can arise. If a series of visual forms are wholly independent of a series obtained by touch we do not treat one as a distorted appearance of the other, but refer them to wholly different things. The significant contra dictions are those which constitute exceptions to a general rule, an incoherence which is partial, not complete, and calls not for the abandonment of the rule but only for a better formulation. Some degree of truth is required even in a mere appearance.

The stage at which we are aware merely of the conflict between appearances without further determination of the situation leaves open two further lines of cognitive development : which of these appearances best presents the real? And how must the false appearance be accounted for? In the solution of these problems attention is still directed to concomitant variations. In the mere conflict between visual and other presentations (tactile and kinaesthetic) there is nothing to suggest that one is more veridical than the rest. There is no peculiar veracity, as has sometimes been supposed, in the testi mony of touch. Examples are easily found where vision is the better guide. It is the series of perceptual judgments which find support and corroboration from other sources which comes to be accepted as the revelation of the real, whilst those which fail to be reinforced by independent evidence are rejected as illusion. Were it possible to reinforce the double images which arise in displacing the eye ball by a corresponding duplication of touch and to preserve the correlation through varied forms of manipu lation the faulty judgment would thereby be confirmed, but such conditions are in detail impossible to obtain.