**2.3 Stimuli, conditions, and task**

The task involved gathering information about a cosmetic article (facial cream) in five different ways (verbal explanation, written explanation, application, smell, and touch) in an environment simulating a cosmetics counter (Fig. 2). The facial cream was in a gold jar without a label bearing the name of a particular product. Five simulation conditions were used. Under the explanation condition, the subjects were asked to understand the explanation about the facial cream provided by a sales person (i.e., a confederate). Under the written condition, the explanation was given by a sales person, but he or she used a text and pictures to provide information about the facial cream. Under the application condition, the subjects were required to apply the facial cream to the back of their left hand. Under the smell condition, they were required to smell the facial cream on their left hand. Under the touch condition, they were required to touch a jar of facial cream. The order of these five conditions corresponded to the sequence above, and each condition lasted 15 sec. A 5-sec preparation time and a 35-sec rest time were added for NIRS data recording (Fig. 3).

The Use of Near-Infrared Spectroscopy to Detect Differences in

(Hb) under the five conditions.

**3.2 Brain activation** 

Brain Activation According to Different Experiences with Cosmetics 61

Fig. 4. An example of the time course of changes in the concentrations of oxy-hemoglobin

data show that the oxy-Hb concentration increased after task onset and decreased after offset under the application, smell, and touch conditions. The brain-activation level was defined as the integral value of the oxy-Hb concentration during the task (15 sec). The average and standard deviation of the activation levels were calculated for each channel across subjects. When the activation level at a channel was higher than the average ±2.5 standard deviations, that channel's data were deleted from analysis under all conditions.

We performed *t*-tests to compare the activation levels with zero. Figure 5 shows the significantly activated channels under the five different conditions. The left and right 48 circles represent channel loci. Red, orange, and yellow circles show that the *p*-values for the test were <0.01, 0.05, and 0.1, respectively. Following Okamoto, Dan, Sakamoto, Takeo, Shimizu, Kohno, Oda, Isobe, Suzuki, Kohyama, and Dan (2004), the channels were located in brain areas. One channel at the left frontal lobe was activated under the explanation condition. This channel is part of Broca's area, and its activation was due to the verbal explanation under the explanation condition. Under the written condition, the left and right superior frontal lobes, corresponding to the supplementary motor area, were activated. Under the written condition, participants needed to integrate the visual and auditory information on the form. These activated areas may have been related to integrated

Fig. 2. Five different ways by which participants learned about a facial cream: a) explanation, b) written, c) application, d) smell, and e) touch.

Fig. 3. Experimental schedule for NIRS recording

### **2.4 Subjective rating**

After the NIRS measurements, subjects used a 100-point scale to rated the face cream with respect to 11 subjective reactions : 1, comfort; 2. relief; 3, conviction; 4, satisfaction; 5, understanding; 6, promise; 7, reliability; 8, likability; 9, willingness to use; 10. interest; and 11, appeal.
