SINGLE-OBJECT STUDIES

CHAPTER 3 SINGLE-OBJECT STUDIES

3.1 ADVANTAGES AND USE The scope of conservation projects and conservation research ranges from one object to

thousands of objects and generic classes of objects. The same is true of the healing, training. and education disciplines that work with human beings. This chapter concentrates on studies of single objects. Such studies are perhaps most important to practicing conservators, who spend much time with a single objects and need to justify particular treatments without always having similar objects available for experimentation. Single-object studies also may aid researchers who are more interested in conservation science than in a particular object but who are studying actual works of art rather than surrogate samples of art materials.

Historically, applied disciplines began with a focus on individuals, with the primary method of research being the case study. This century has seen a shift of emphasis in research and experimental design toward group comparison methods. The latter is the primary content of most books on experimental design and analysis.

[n recent years, there has been a revival of interest in single-subject studies for gaining knowledge (Barlow and Hersen 1984). This does not mean a return to subjective case studies. [t instead means applying the principles used in group studies to derive statistically valid conclusions from single-subject studies. The key idea is that an experimenter can sometimes make an object serve as its own control by treating it more than once in a formal experimental design. It is therefore possible to make formal statistical statements comparing treatments applied to only one object. Such designs are alternatives to case-study

trial-and-error. They should result in a more rapid accumulation of knowledge. Strictly speaking. the results of a single object study are applicable only to that object. However, the conservator who must treat a particular object. just like the doctor who must treat a live patient, can use objective substantiated conclusions to plan a treatment for that

object and to develop knowledge for future projects. Single-object studies also may interest researchers who would otherwise prefer more general results. Material may be in short supply, especially for destructive experiments. Resources may be limited or uncertain. A complete study on one or two objects is better than an incomplete study on six that is prematurely terminated as resources run out. The treatment protocol for an experiment may be in flux and subject to change after the experience with each object. A series of completed single-object studies may lead to the desired generalizations.

Compared to human beings, art objects have advantages for individual study. Most treatments of human subjects are systemic and affect the entire body or at least an entire organ. Multiple treatments of one patient must nearly always be given at different times.

Over-the-counter headache remedies are a typical example. A limited exception is the simultaneous application of skin treatments that have only local effects. Art objects can more often receive different treatments at different places within one treatment session. Conservation researchers therefore have added flexibility for designing rapid studies.

A second advantage of art objects is that the effect of time is more stable and predictable. Unlike human medical subjects, objects do not spontaneously heal themselves. We can more plausibly conclude that observed improvement results from treatment. Bronze disease does not cure itself, whereas organisms are active entities and tumors sometimes disappear without a doctor's intervention. The art object might get worse, but it rarely cures itself.

Art conservation has the additional advantage of greater stability and dependability of treatment outcome. We use this in everyday conservation practice to make cause-and­ effect conclusions. However, people can

be fooled. Coincidences do occur and are constantly subject to misinterpretation. People remember dreams that come true much

better than they recall those that do not. But it is harder to apply a treatment and not notice that there has been no effect.

In part, this chapter builds upon the everyday art conservation practice of testing patches on an art object. It develops that practice into formal, statistically analyzable experiments. Once learned, the techniques often require relatively little extra time, perhaps an hour or so. This is not much compared with the total time involved in some treatments.

We are not suggesting that every treatment on every object be subject to a rigorous test. Instead, we discuss when and how one justifies making routine conclusions that a treatment works, give suggestions on how to proceed when its value is not so clear, and show how to test an object's treatment statistically by applying it to test patches within test intervals.