ANALYSIS OF PSYCHOLOGICAL PROPERTIES OF COSMETICS 87 be reduced by use of the actual product under known controlled conditions. Since memory is imperfect, little precise knowledge is gained by asking consumers what they think of Blink Eye Shadow or Farley's Skin Balm. If precise control of respondents' environment is not provided, incidental distraction, misinterpretation of instructions, and other factors can destroy the sensitivity and significance of any study. Incidentally, we find in this same context that it is only wastefully wishful to expect Mr. or Mrs. Consumer to design or redesign your product. They are not sufficiently motivated, nor are they articulate or experienced enough to tell you what consistency a vanishing cream should have or what odor is ideal in a hand soap. Under the right conditions they can provide almost unlimited infor- mation about the present product, but rarely can they state what should be done to improve it. Before proceeding with other illustrations, perhaps we should define some of the terms we have used and will use. DEFINITIONS First, what is the difference between psychometrics and psychophysics, both of which have been referred to earlier? Psychophysics can be illus- trated by a test of the perceived length of three lines on a sheet of paper or of the perceived weight of three scraps of paper. In each instance, the psychological judgment can be checked with the aid of a simple physical measure of linear or weight dimensions such as a foot ruler or a balance. When it is not possible to apply a parallel physical scale, then the study be- comes clearly psychometric. For example, there is no physical measure of the beauty of a package, a lipstick, or a lady of the pleasantness of feel of a facial cream the pain from a razor blade the readability of a label. Then we must turn to Psychometrics. In certain cases, no physical meas- ure has yet been devised as in the case of odor, while in other examples physical measures are too insensitive to be of help, as with tactual qualities. NTUMBERS DON'T MAKE VALID MEASUP. EMENT We must remember too, that mere physical measures of the stimulus materials may be meaningless or misleading. For example, photometric readings of hair reflectance may disagree with perceived luster, or, similarly, rheological assays of a vanishing cream may bear no relation to the "greas- iness" or "fiufiSness" of the preparation. Some texts list more than a hundred variations of the comparatively small number of basic psycho- physical and psychometric methods (5). Most familiar methods include Limits, Equal Appearing Intervals, Constant Stimulus Dif}erences, Produc- tion, and Average Error, all of which are basic to psychophysics, while Paired Comparison, Rank Order, Triangle and Single Stimuli Tests are more common to psychometrics.

88 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS We mentioned the absolute judgment or rating scale methods. It should be remembered that no judgment is ever strictly absolute but is always com- parative in the sense that one's experience invariably influences the so- called absolute judgment. As a consequence, at least the most recent ob- server experiences should be controlled or taken into account. A rank or- der indication with more than five items may cause trouble in interpre- tation for the reason that interest wanes with the long task of arranging in order, and with lack of interest goes the sense of responsibility for best effort. Before turning to the use of the methods we have just mentioned in evaluating cosmetics, we will examine in broadest terms how they may be applied to "difference" determinations preference study, and quality anal- ysis difference. The difference methods may be divided into two groups, one of which includes a designated standard for reference and the other requires that the observer examine all stimuli from some particular point of view dictated by the instruction. In certain cases, one approach is more sensitive, while in others, the reverse is true. The preference studies, by the same token, can be divided into comparative and absolute methods ranging from the simple "which do you prefer" to the absolute rating scale of nine points applied to a single product. In many instances, we find com- parative methods impractical and must resort to the absolute. When both can be used, we have observed excellent agreement or correlation. Finally, the analysis of quality may be approached directly or indirectly, by classification or comparison, by description, or by general behavior study. Let's begin with a study of shaving cream to illustrate the propositional approac h which precedes the test work. When possible, the univariate procedure is most valuable in order that the relative importance of each variable can be assessed as it is individually studied. As Ev^ru^zIOS or Ss^viso C•s^•as (^ Ss•ISS or PROPOSITIONS) General Propositions 1. Differences Exist: The composite of properties of shaving creams produce measurable differences in their effects on shaving. 2. Quality Uniformity Makes Measurement Valid: The variations in the quality of a shaving cream produced by any given manufacturer is less than the differences between the creams of various manufacturers. 3. The Several Effects Produced Will Be of Measurable Importance: The differences in the whisker conditioning abilities of the several creams will produce a number of effects, each of which can be measured and as- signed weights in relation to its importance to shavers. 4. Some Desirable Properties: Other things equal, a good cream will