It must be emphasized that there are many different moods, or modes of composition, that are possible in interior design. The recognition of this fact makes it difficult to apply valid critical criteria to these modes, since many of them are intensely personal. What may appear to be picturesque to one person might be ugly or cluttered to another. Each person brings to interior design his own cultural mores and his own prejudices, and in many ways he is psychologically conditioned and influenced to accept certain things and to reject others. In discussing various modes of composition, one must therefore take into consideration the occupants and their backgrounds, the locale and site, and then try to apply the most basic design principles as general guidelines.

Formal and informal compositions are relatively easily defined and classified; in fact, this distinction is useful throughout the history of furniture and interiors. Formal styles are usually associated with life at court or furnishings for the palatial homes of nobles or a moneyed elite. The informal periods usually are associated with rural living or the simpler pieces of furniture made by the local craftsmen in rural areas, where they plied their trade with limited tools, using local woods. Formal furniture, as a rule, leads to formal interior compositions. Balance and symmetry certainly tend to lead to formal compositions. Formality is not associated with any particular period. In fact, a very famous contemporary chair, the Barcelona chair by Mies van der Rohe, is an extremely formal and elegant piece. It would seem wrong to use that chair in a casual catercorner room arrangement.

Setting strongly influences the character of a space. By its very definition, a rustic setting would be rural and informal and would seem wrong and incongruous in a formal townhouse or city apartment. Since most business and public interiors are located in urban centres, any attempt to make such interiors look rustic or homey would be an aesthetic paradox. By the same token, it would appear equally incongruous to design a restaurant located in an old mill or barn in New England in a formal and urban character with elegant furnishings, whether they were contemporary or antiques of a formal nature.

Certain modes of composition are determined by the function of the spaces as much as by the location and by the architecture. For example, a cozy or homey interior is normally associated with residential interiors or similarly intimate interiors, such as restaurants that may wish to appear “cozy.” Some interiors, such as discotheques, require excitement and other interiors, such as funeral parlors, require serenity or dignity. One expects certain modes of composition for certain functions, but one’s expectations are subject to many external influences, such as personal background, location, psychological associations, and changing fashions. For instance, the typical bank interior until about 1950 was expected to be solid, dignified, awe-inspiring, formal, and above all confidence inspiring. Contemporary design for business and industry has become accepted by all, and the early 1950s saw the logical extension of these firmly established design principles into the area of bank design. One of the first radical departures of traditional design for banking spaces was the Manufacturers Trust Company Manhattan office designed by Skidmore, Owings and Merrill in the early 1950s. It was the first widely published “glass” bank, and it set a trend that has become the new mode of composition for banks.

Fashion or design trends influence one’s reactions to many kinds of designs. The term clutter is usually associated with Victorian design of the 19th century. Under the usual definition of the term clutter, one thinks of home interiors with collections of accessories and with an overabundance of knickknacks—the typical Victorian home. In the mid-1960s a new approach to office design, reflecting the “cluttered” approach, was developed. This office appears disorganized at first glance. Actually, the system (called office landscape; see below Kinds of interiors: Public interiors: Space planning) is very efficient and for that reason is deemed acceptable, even if the visual impact tends to be chaotic. Traditionally, office and business interiors were pristine, orderly, and very organized, and the idea of a cluttered appearance would have been anathema to designers.

The most difficult mode of composition for objective analysis is one that some people call exotic. The chances are that all exotic interiors are highly personal statements and cannot be rationally understood in theoretical design terms. To begin with, what may appear exotic to the average American could be very ordinary or even homey to another culture. Japanese or oriental design in general serves as an example. A Japanese style interior is extremely subtle, serene, and understated, yet to the uninitiated such an interior will appear exotic. Undoubtedly that same phenomenon holds true in reverse. Oriental people have often been impressed with Western-style design and have adopted it presumably because to them it appeared exotic. The increased mobility of the middle classes of many nations today has made foreign travel possible for more and more people, thereby tending to soften some of the very strong regional differences in design. The modes of composition are still discernible nationally or certainly by major geographic and ethnic divisions, but they tend to be less distinct. Many subtle differences exist within the same country, some of which are based on varying socioeconomic backgrounds, much in the manner of the traditional difference between formal styles (at court and in homes of nobility) and informal modes of composition for the country people and middle classes. The labels that one applies to these modes of composition are often only descriptive. They must not be confused with objective evaluation of design values. An interior that is by the creator’s definition exotic or picturesque may or may not be a well-done exotic design.