Evaluation of Pleasure-Displeasure Induced by Use of Lipsticks with Near-Infrared Spectroscopy (NIRS): Usefulness of 2-Channel NIRS in Neuromarketing.

In order to examine whether near-infrared spectroscopy (NIRS) would be a useful neuromarketing tool, we employed NIRS to evaluate the difference of pleasure-displeasure in women, induced by the use of different types of lipsticks. The subjects used lipsticks A and B; A is softer than B. Concentration changes of oxy-Hb were measured in the bilateral prefrontal cortex (PFC) during use of lipsticks A and B. We evaluated the right and left dominancy of PFC activity by calculating the Laterality Index (LI) (LI = leftΔoxy-Hb - rightΔoxy-Hb); positive LI indicates left-dominant activity while negative LI indicate right-dominant activity. We found a significant interaction between the use of lipsticks A and B, using a two-way factorial analysis of variance [F(1,13) = 9.63, p < 0.01]; Δoxy-Hb in the left PFC was larger than that in the right PFC during the use of lipstick A, while Δoxy-Hb in the right PFC tended to be larger than that in the left PFC during the use of lipstick B (p < 0.1). The LI of lipstick A was larger than that of lipstick B (paired T-test, p = 0.0083). We suggest that lipstick A caused a more positive emotional response than lipstick B, since greater left than right frontal cortical activity is associated with positive affect. These results suggest that 2-channel NIRS may be a useful neuromarketing tool, since it allows objective assessment of pleasure-unpleasure.