**3.1 NIRS data analysis**

Trials that had movement artifacts, as reflected by steep changes in the time series of the oxy-Hb and deoxy-Hb concentrations, were removed from the analysis. After these data were eliminated, we focused on oxy-Hb concentrations as the index of brain activation. Many NIRS studies use changes in oxy-Hb concentrations as the primary foci of analyses (e.g., Matsuda & Hiraki, 2006; Otsuka, Nakato, Kanazawa, Yamaguchi, Watanabe, Kakigi, 2007) because these values are the most sensitive to changes in regional cerebral blood flow and are correlated with the blood-oxygen-level dependence (BOLD) signal (Hoshi, Kobayashi, & Tamura, 2001; Strangman, Culver, Thompson, & Boas, 2002).

Before starting the actual data analysis, the relative oxy-Hb concentrations at baseline (the line in the data repesenting oxy-Hb concentrations between the 5-sec preparation time and the last 5-sec rest time ) were calculated, which reduced low–frequency noise. Moreover, if the calculated relative oxy-Hb concentration values included an artifact, such as alternating current noise due to the poor contact of the probe with the skin, data from that channel under all conditions were deleted.

Data from one channel of one subject are shown in Fig. 4. The horizontal axis shows time from the beginning of the task, and the vertical axis shows oxy-Hb changes. This subject's

5 sec 20 sec 55 sec

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

Trials that had movement artifacts, as reflected by steep changes in the time series of the oxy-Hb and deoxy-Hb concentrations, were removed from the analysis. After these data were eliminated, we focused on oxy-Hb concentrations as the index of brain activation. Many NIRS studies use changes in oxy-Hb concentrations as the primary foci of analyses (e.g., Matsuda & Hiraki, 2006; Otsuka, Nakato, Kanazawa, Yamaguchi, Watanabe, Kakigi, 2007) because these values are the most sensitive to changes in regional cerebral blood flow and are correlated with the blood-oxygen-level dependence (BOLD) signal (Hoshi,

Before starting the actual data analysis, the relative oxy-Hb concentrations at baseline (the line in the data repesenting oxy-Hb concentrations between the 5-sec preparation time and the last 5-sec rest time ) were calculated, which reduced low–frequency noise. Moreover, if the calculated relative oxy-Hb concentration values included an artifact, such as alternating current noise due to the poor contact of the probe with the skin, data from that channel

Data from one channel of one subject are shown in Fig. 4. The horizontal axis shows time from the beginning of the task, and the vertical axis shows oxy-Hb changes. This subject's

Kobayashi, & Tamura, 2001; Strangman, Culver, Thompson, & Boas, 2002).

a) b) c) d) e)

Fig. 2. Five different ways by which participants learned about a facial cream:

a) explanation, b) written, c) application, d) smell, and e) touch.

Preparation Rest

Test

Fig. 3. Experimental schedule for NIRS recording

**2.4 Subjective rating** 

**3.1 NIRS data analysis** 

under all conditions were deleted.

11, appeal.

**3. Results** 

5 sec 15 sec 35 sec

Fig. 4. An example of the time course of changes in the concentrations of oxy-hemoglobin (Hb) under the five conditions.

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.

#### **3.2 Brain activation**

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

The Use of Near-Infrared Spectroscopy to Detect Differences in

correlated with impression and WTU.

L1:Impression, WTU L4:Impression, WTU L8:Impression

22

d) e)

L23:Impression, WTU R7:Impression R14:Impression R22:Impression, WTU

**3.4 Brain activation and subjective ratings** 

7 14

1 4 8

23

and WTU

Brain Activation According to Different Experiences with Cosmetics 63

Figure 6 shows the channels showing statistically significant correlations with impression or WTU. Under the explanation condition, brain activation in the left inferior frontal lobe was correlated with impression and WTU. Under the written condition, brain activation in the left parietal lobe was correlated with impression, and that in the right superior frontal lobe was correlated with impression and WTU. Under the application condition, brain activation in the left superior frontal lobe and lateral lobe was correlated with impression, that in the right superior frontal lobe was correlated with impression, and that in the right parietal and lateral lobes was correlated with impression and WTU. Under the smell condition, brain activation in the left parietal lobe was correlated with impression and WTU, that in the right inferior frontal lobe was correlated with impression, and that in the right parietal lobe was correlated with impression and WTU. Under the touch condition, brain activation in the left parietal lobe was correlated with impression, and that in the right parietal lobe was

20

a) b) c)

5 8 12

L20:Impression R5:Impression, WTU R8:WTU R12:WTU

20 18

Fig. 6. Channels with statistically significant associations of brain activation with impression

We analyzed the correlation between subjective ratings of the facial cream and brain

We found the following relationships between brain activation and subjective ratings for impression and WTU. Under the explanation condition, brain activation in the left frontal

activations using the dichotomy between impression and WTU described above.

22

L20:Impression, WTU R18:Impression, R22:Impression,

3

1 4

22

L3:Impression L23:Impression R1:Impression R4:Impression R14:Impression R16:Impression R17:Impression, WTU R22:Impression, WTU

16

14

17

23

Fig. 5. Channels with statistically significant brain activation

processing. More channels and more areas were activated under the next three conditions than under the explanation and written conditions. Under the application condition, the left and right frontal and lateral lobes were activated. Under the smell condition, the strongest activation location shifted in the superior direction in the left hemisphere and activation in the right frontal area increased compared with that under the application condition. Moreover, activation in the lateral lobes was weakened compared with that under the application condition, and activation in the parietal lobes was also evident. Under the touch condition, activation in the left parietal lobe disappeared and activation in the right frontal lobe weakened compared with the results under the application condition. Under the latter three conditions, participants were required to perform motor actions and engage in sensory-information processing, which may have activated broader areas in the corresponding motor and sensory areas. These results indicate that different ways of considering a facial cream activated different brain areas.

#### **3.3 Brain activation and subjective ratings**

We analyzed the correlation between the subjective ratings and brain activation. The 11 subjective ratings were classified into two subtypes: "impressions" of the facial cream (1, comfort; 2, relief; 3, conviction; 4, satisfaction; 5, understanding; 6, promise; 7, reliability; 8, likability) and "willingness to use" (WTU) (9, willingness to use; 10, interest; 11, appeal.).

processing. More channels and more areas were activated under the next three conditions than under the explanation and written conditions. Under the application condition, the left and right frontal and lateral lobes were activated. Under the smell condition, the strongest activation location shifted in the superior direction in the left hemisphere and activation in the right frontal area increased compared with that under the application condition. Moreover, activation in the lateral lobes was weakened compared with that under the application condition, and activation in the parietal lobes was also evident. Under the touch condition, activation in the left parietal lobe disappeared and activation in the right frontal lobe weakened compared with the results under the application condition. Under the latter three conditions, participants were required to perform motor actions and engage in sensory-information processing, which may have activated broader areas in the corresponding motor and sensory areas. These results indicate that different ways of

We analyzed the correlation between the subjective ratings and brain activation. The 11 subjective ratings were classified into two subtypes: "impressions" of the facial cream (1, comfort; 2, relief; 3, conviction; 4, satisfaction; 5, understanding; 6, promise; 7, reliability; 8, likability) and "willingness to use" (WTU) (9, willingness to use; 10, interest; 11, appeal.).

Fig. 5. Channels with statistically significant brain activation

considering a facial cream activated different brain areas.

**3.3 Brain activation and subjective ratings** 

Figure 6 shows the channels showing statistically significant correlations with impression or WTU. Under the explanation condition, brain activation in the left inferior frontal lobe was correlated with impression and WTU. Under the written condition, brain activation in the left parietal lobe was correlated with impression, and that in the right superior frontal lobe was correlated with impression and WTU. Under the application condition, brain activation in the left superior frontal lobe and lateral lobe was correlated with impression, that in the right superior frontal lobe was correlated with impression, and that in the right parietal and lateral lobes was correlated with impression and WTU. Under the smell condition, brain activation in the left parietal lobe was correlated with impression and WTU, that in the right inferior frontal lobe was correlated with impression, and that in the right parietal lobe was correlated with impression and WTU. Under the touch condition, brain activation in the left parietal lobe was correlated with impression, and that in the right parietal lobe was correlated with impression and WTU.

Fig. 6. Channels with statistically significant associations of brain activation with impression and WTU

#### **3.4 Brain activation and subjective ratings**

We analyzed the correlation between subjective ratings of the facial cream and brain activations using the dichotomy between impression and WTU described above.

We found the following relationships between brain activation and subjective ratings for impression and WTU. Under the explanation condition, brain activation in the left frontal

The Use of Near-Infrared Spectroscopy to Detect Differences in

**4.4 Advantage of NIRS for studying everyday situations** 

showed a correlation between brain activation and subjective ratings.

participants move with relative freedom.

*Neuroimage,* 16:1120–5.

*Psychonomic Science, 28, 2–16.*

*Physiology*, 90, 1657*–*1662.

29, 706*–*711.

1288.

reward circuitry. *NeuroReport,* 13:2499*–*2503

commercial domains.

**5. Conclusion** 

**6. References** 

Brain Activation According to Different Experiences with Cosmetics 65

results indicate the operation of a common brain mechanism in this regard. However, culture may nonetheless influence impressions, WTU, WTB, and brain activation related to these judgments. The cultural differences involved in-store shopping behaviors need to be understood given that such differences carry important implications for both academic and

The participants in the current study moved their arms and hands to apply a facial cream and touched jar. These actions are not permitted in magnetic resonance imaging scanners, and they also cause strong electroencephalogram artifacts due to muscle potentials. Thus, brain monitoring with NIRS is the only acceptable technique to use in situations in which

The current study was to investigate the relationship between different ways of learning about a cosmetic and brain activations. In the current experiment, participants learned about a facial cream in five different ways while their brain activity was monitored, and then rated their impressions and WTU on the facial cream. The results suggested that different ways of learning about a facial cream activated different brain areas. Moreover, some channels

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Kubota, Y., Toichi, M., Shimizu, M., Mason, R. A., Findling, R. L., Yamamoto, K., &

Matsuda, G., & Hiraki, K. (2006). Sustained decrease in oxygenated hemoglobin during

Okamoto, M., Dan, H., Shimizu, K., Takeo, K., Amita, T., Oda, I., Konishi, I., Sakamoto, K.,

near-infrared spectroscopy study. *Neuroimage*, 31, 1783-1789.

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lobe was correlated with impression and WTU; under the written condition, brain activation in the right superior frontal lobe was correlated with impression and WTU. Under the application condition, brain activation in the right superior frontal and parietal areas were related to impression and WTU. Under the smell and touch conditions, activation in the left and right parietal lobes was related to impression and WTU.
