116 JOURNAL OF COSMETIC SCIENCE procedure where the subject's index or middle finger applies a sample of the product onto the subject's skin using a circular "rubbing" motion. Indeed, it is likely that most consumers base much of their evaluation of creams/lotions during self-application using their fingers. Most sensory methods require subjects to evaluate specific attributes at a single specific time. This assessment time is often after a sample has been applied or otherwise ma- nipulated. For example, a subject might evaluate "greasiness" or "creaminess" of a lotion product soon after a sample quantity was applied. In effect, the subject is requested to time-average his or her response, arriving at a single value to represent what may in reality be a dynamic situation. Skin-care products may spread, dissolve, melt, thin, penetrate, evaporate, etc., during (and after) the initial application. These are dynamic events the expectation that the associated sensory evaluation is "static" (or can be characterized by a single time-averaged value) may be inappropriate. In general, poten- tial information regarding the temporal behavior of the response is not provided by single-point sensory perception protocols. So-called time-intensity (TI) sensory techniques are designed to capture responses in real time. TI techniques, therefore, provide information on the dynamic nature of the re- sponse. It has been shown (5) that TI techniques provide significantly more information than single-point techniques. TI techniques have been employed in food product de- velopment and other areas such as fragrances and perfumes to provide quantitative information on the temporal behavior of sensory parameters of interest (usually olfactory or gustatory). Food evaluations also include tactile attributes (for example, see reference 6). ASTM Committee E-18 is currently developing a standard document on TI tech- niques that includes computerized data acquisition techniques and data analysis. Applications of TI techniques to the sensory evaluation of creams and lotions appears to be limited. ASTM method E 1490 does describe a procedure to obtain temporal data on skin feel attributes during the application process. More specifically, the ASTM rub-out procedure rates parameters such as spreadability, denseness, and wetness after 3, 6, 9, 12, and 15 rubs. The main objective of this research was to apply TI techniques to the evaluation of the attribute as "soothing" while skin-care products were applied. More specifically, the soothing intensity was evaluated every ten seconds while a skin-care product (lotion or petroleum jelly) was applied during a two-minute rub-out. The utility of the TI ap- proach would be demonstrated by the identification of time-related behavior in the responses. In addition, the following hypothesis was tested: a subject's evaluation of "soothing" is a function of who is applying the product. In other words, the same product will be perceived as less soothing when the product is applied by another person as opposed to self-application. MATERIALS AND METHODS SUBJECTS Twenty female students in the age group 19 to 26 participated in the study. All subjects were not informed of the purpose of the study. Subjects were screened for existing skin-related problems. In addition, no stringed musical instrument players or others

TIME-INTENSITY "SOOTHING" EVALUATION 117 with calluses on their fingers were allowed to participate. Subjects were also instructed to refrain from the application of any skin-care products (other than soap) to the back of their hands for at least ten days prior to the start of the study and during the study period (approximately three weeks). A questionnaire was developed to determine the subject's current skin-care product usage behavior. Questions addressed each of the following: 1) usage frequency of general skin-care products (other than soap) designed to moisturize or treat/prevent dry skin and 2) usage of additional bath soap product with added moisturizers or lotions. Subjects also identified themselves as either right-hand or left-hand dominant (all were right-hand dominant). In addition, subjects were asked if they had recently exposed their hands to any harsh chemicals (no positive responses). SAMPLES Two different samples were employed: petroleum jelly (Vasdine ©, 100% petroleum jelly, Chesebrough-Ponds USA Co., Greenwich, CT) and lotion (Jergen's © "Original Scent" Advanced Therapy Lotion, The Andrew .Jergens Co., Cincinnati, OH). Application amounts were approximately 5 ml (1 teaspoon) per evaluation, provided in unmarked paper containers (lotion samples) or on wax paper squares (petroleum jelly samples). Samples were at room temperature during the testing. In addition to these two product samples, subjects and other applicators also performed the application motions with their bare fingers as a reference condition. EVALUATION PROCEDURE The scale used to rate the soothing intensity of a product is presented in Table I. Subjects were instructed in this scale prior to the initiation of the evaluations. A copy of the scale was provided in a convenient location for referral by the subject as necessary. Two general types of procedures were employed: 1) self-application and 2) other-application. The basic procedure was as follows: for the self-applied product evaluations, subjects were presented the unmarked sample and instructed to place the sample onto the back of the designated hand. Subjects then immediately proceeded to rub the product onto the skin surface with their three middle fingers of the opposite hand, using circular motions. Every ten seconds (starting after the initiation of rubbing) subjects would determine the soothing intensity, reporting their score to the attendant, who recorded the scores in such a manner that the rarer could not see the recorded scores. Using a Table I Evaluation Scale Used to Rate "Soothing" Rating Description 0 Not soothing at all 1 Very low level of soothing 2 Low level of soothing 3 Moderate level of soothing 4 High level of soothing 5 Very high level of soothing