**1. Introduction**

56 Infrared Spectroscopy – Life and Biomedical Sciences

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#### **1.1 Economic behavior and brain imaging**

Human economic and purchasing behavior has been studied primarily with brain imaging techniques such as functional magnetic resonance imaging (fMRI). One common topic in this domain of investigation is the willingness to pay (WTP). An essential component of every marketplace transaction is a WTP calculation in which buyers calculate the maximum amount of money they are willing to pay in exchange for the object being sold. WTP decisions are related to activation in the (medial) orbitofrontal cortex (OFC) (Wallis & Miller, 2003; Padoa-Schioppa & Assad, 2006; Erk, Spitze, Wunderlich, Galley, & Walter, 2002; Rolls, 1996; Plassmann, O'Doherty, Rangel, 2007; Schoenbaum, Chiba, & Gallagher, 1998; Tremblay & Schultz, 1999; Roesch & Olson, 2004). Medial OFC activation is related to choice or preference in the absence of explicit attention to the products presented, suggesting that the WTP calculation occurs implicitly. These studies have been performed under both wellcontrolled experimental settings and artificial environments because of the restrictions involved in using fMRI techniques. Although fMRI offers advantages related to the spatial resolution of cognitive and deep-brain activities, it requires a high degree of patient restraint during measurements made in pediatric research settings.

#### **1.2 Advantages of using near-infrared spectroscopy**

Near-infrared spectroscopy (NIRS) is a relatively new imaging technique that is noninvasive, highly flexible, and requires less participant restraint and sedation; it also produces continuous real-time measurements (Baird, Kagan, Gaudette, Walz, Hershlag, & Boas, 2002; Endo, Nagai, Kumada, 2009; Kubota, Toichi, Shimizu, Mason, Findling, Yamamoto, & Calabresea, 2006; Matsuda & Hiraki, 2006; Otsuka, Nakato, Kanazawa, Yamaguchi, Watanabe, & Kakigi, 2007). The NIRS technique has been successfully used in investigations of the neural correlates of complex actions such as walking and running on a treadmill (Suzuki, Miyai, Ono, Oda, Konishi, Kochiyama, & Kubota, 2004), peeling an apple (Okamoto, Dan, Shimizu, Takeo,

The Use of Near-Infrared Spectroscopy to Detect Differences in

Brain Activation According to Different Experiences with Cosmetics 59

Fig. 1. Positions of optodes placed on the prefrontal regions of both hemispheres. The distance between each emitter (indicated by light gray squares) and the corresponding detector (indicated by dark gray squares) was 3 cm. These emitters and detectors were

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).

placed in probes with 4 × 4 arrays.

**2.3 Stimuli, conditions, and task** 

Amita, Oda, Konishi, Sakamoto, Isobe, Suzuki, Kohyama, & Dan, 2004), demonstrating that NIRS can be applied to real-life situations involving actions and movements.

#### **1.3 In-store buying experiences and brain imaging**

Many different ways of trying articles/products at stores exist, including touching and listening to explanations offered by sales persons. However, the most effective ways to provide a good impression to customers or increase the chance that customers will purchase a given item remains unclear. Additionally, the association of the formation of an impression and buying behavior with brain activation has not been investigated. In actual situations, sales persons have a variety of ways to explain the features of articles to be sold. In the present study, we simulated a situation in which a customer (i.e., participant) and a sales person (i.e., confederate) interacted in five different ways.
