We may gain some notion of the way in which this effect is produced from the important part that certain elements connected with the impression play in the process, for example, the sensations of ocular position and movements in visual ideas. Obviously it is these immediate sensational elements that serve to pick out from the mass of ideational elements which react upon the impression, certain particular ones that correspond to themselves, then bring these selected factors into a form agreeing with that of the rest of the components of the immediate impression. At the same time it appears that not merely the [p. 233] elements of our memory-images are relatively indefinite and therefore variable, but that even the perception of indefinite impression may vary under special conditions fairly wide limits. In this way the assimilative process starts primarily from elements of the immediate impression, chiefly from particular ones which are of preeminent importance for the formation of the idea, as, for example, the sensations of ocular position and movement in visual ideas. These elements call up certain particular memory-elements corresponding to themselves. These memories then exercise an effect on the immediate impression, and the impression in turn reacts in the same way on the reproduced moments. These separate acts are, like the whole process, not successive, but, at least for our consciousness, simultaneous. For this reason the product of the assimilation is apperceived immediate, unitary idea. The two distinguishing characteristics of assimilation are, accordingly, 1) that it is made up of a series of elementary processes of combination, that is, processes that have to do with the components of ideas, not with the whole ideas themselves, and 2) that the united components modify one another through reciprocal assimilations .
11. On this basis we can explain without difficulty the differences between complex assimilative processes, by the very different parts that the various factors necessary to such a process play in the various concrete cases. In ordinary sense-perceptions the direct elements are so predominant that the reproduced elements are as a rule entirely overlooked, although in reality they are never absent and are often very important for the perception of the objects. These reproduced elements are much more noticeable when the assimilative effect of the directelements is hindered through external or internal influences, such as indistinctness [p. 234] of the impression or affective and emotional excitement. In all cases where the difference between the impression the idea becomes, in this way, so great that it is apparent once on closer examination, we call the product of assimilation an illusion .
The universality of assimilation makes it certain that such processes occur also between reproduced elements, in such a way that any memory-idea which arises in our mind is immediately modified by its interaction with other memory-elements. Still, in such a case we have, of course, no means of demonstration. Al1 that can be established as probable is that even in the case of so-called "pure memory-processes" direct elements in the form of sensations and sense-feearoused by peripheral stimuli, are never entirely absent.reproduced visual images, for example, such elementspresent in the form of sensations of ocular position and movement. b. Complications.
12. Complications, or the combinations between upsychical compounds, are no less regular components of consciousness than are assimilations. Just as there is hardly intensive or extensive idea or composite feeling which imodified in some way through the processes of reciprocal assimilation with memory-elements, so almost every one of these compounds is at the same time connected with other, dissimilar compounds, with which it has some constant relations. In all cases, however, complications are different from assimilations in the fact that the unlikeness of the compamakes the connection looser, however regular it may be, so that when one component is direct and the other reproduced, the latter can be readily distinguished at once. Still, is another reason which makes the product of a complication [p. 235] unitary in spite of the easily recognized difference between its components. This cause is the predominance of one of the compounds, which pushes the other components into the obscurer field of consciousness.
If the complication unites a direct impression with memory-elements of disparate character, the direct impressionassimilations is regularly the predominant component while the reproduced elements sometimes have a notice-able influence only through their affective tone. Thus, when we speak, the auditory word-ideas are the predominant components, and in addition we have as obscure direct motor sensations and reproductions of images of the words. In reading, on the other hand, the visual images come to the front while the rest become weaker. In general it may be said that the existence implication is frequently noticeable only through thecoloring of the total feeling that accompanies thelent idea. This is due to the ability of obscure ideas to have a relatively intense effect on the attention throughbctive tones (p. 216). Thus, for example, theic impression of a rough surface, a dagger-point,arises from a complication of visual and tactuals, and in the last case of auditory impressions ast as a rule such complications are noticeable onlythe feelings they excite. B. SUCCESSIVE ASSOCIATIONS.