We have not yet spoken of the suggestive power of the means of propaganda. Every one knows the influence on taste and smell, on social vanity, on local pride, on the gambling instinct, on the instinctive fear of diseases, and above all on the sexual instinct, can gain suggestive power. Everywhere among the uncritical masses such appeals reach individuals whose psychophysical attitudes make such influences vivid and overpowering. Every one knows, too, those often clever linguistic forms which are to aid the suggestion. They are to inhibit the opposing impulses. The mere use of the imperative, to be sure, has gradually become an ineffective, used-up pattern. It is a question for special economic psychotechnics to investigate how the suggestive strength of a form can be reinforced or weakened by various secondary influences. What influence, for example, belongs to the electric sign advertisements in which the sudden change from light to darkness produces strong psychophysical effects, and what value belongs to moving parts in the picture?
The psychologist takes the same interest in the examples of window displays, sample distributions, and similar vehicles of commerce by which the offered articles themselves and not their mere picture or description are to influence the consciousness of the prospective customer. Here, too, every element may be isolated and may be brought under psychotechnical rules. The most external question would refer to the mere quantity of the presented material. The psychologist would ask how the mere mass of the offering influences the attention, how far the feeling of pleasure in the fullness, how far the æsthetic impression of repetition, how far the associative thought of a manifold selection, how far the mere spatial expansion, affects the impression. In any case, as soon as it is acknowledged as desirable to produce with certain objects the impression of the greatest possible number, the experimental psychologist stands before the concrete problem of how a manifoldness of things is to be distributed so that it will not be underestimated, perhaps even overestimated as to quantity. Again, the laboratory experiment would not proceed with real window displays or real exhibitions, but would work out the principle with the simplified experimental means.