Analysis of How Impressions are Fixed After One Week of Listening to Music Using Subjective Evaluation and Brain Activity Measurement
Authors: Kamada Kouki , Endo Anna , Takahashi Naoki , Sakamoto Takashi , Kato Toshikazu 
Published: June 2022

In advertising and marketing, information is often repeatedly presented to consumers to increase their interest and sensitivity. This method is based on what is known in psychology as the ‘mere exposure effect’. In contrast, there is a growing interest in "neuromarketing," the application of brain science ideas to marketing, and the relationship between various psychological effects and brain activity in marketing. Brain measurements have also been used to study the mere exposure effect.However, although there have been various neuroscientific studies and verifications of the mere exposure effect, there have been few experiments that involve multiple exposure to stimuli across days. Therefore, we measured brain activity to investigate the effect of stimulus presentation across multiple days on impressions.In this study, we conducted an experiment in which subjects listened to music every day for a week. On the first day, when the subjects listened to the music for the first time, we conducted subjective evaluations of liking and brain function measurements. The next day, they listened to the music once every day, at home, for five days. On the last day, six days after the first day, we conducted the same subjective evaluation and brain function measurements as on the first day. To create music stimuli that the subjects had never perceived before, an automatic music creation tool was used.During brain activity measurement using optical topography, we focused on the change in the impression of likeability. In optical topography, the change in the concentration of Oxy-Hb in the brain blood flow was measured as a time-series data volume based on functional near-infrared spectroscopy (fNIRS). In the human brain, the amount of Oxy-Hb in specific activity areas increases with time. By measuring the increase and decrease in Oxy-Hb, we can understand how the subject responds to stimuli.We experimented with 10 healthy right-handed undergraduate and graduate students in their 20s (8 men and 2 women, average age 22.6 years) who provided informed consent, following the rules of the Ethics Committee of Chuo University.Consequently, the verification of impression evaluation, which is a subjective evaluation, showed that the impression evaluation increased significantly from the first day to the last day. At this point, it can be said that the mere exposure effect occurred through repeated listening. An analysis of the brain blood flow data showed that the prefrontal cortex became more active during the processing of negative impressions. In particular, the activity of the DLPFC may be deeply involved in the judgment of impressions. Although this was considered a hypothetical event in the previous study, it was clarified in this study without contradicting the data. The results also suggest a new possibility that the brain activity of first impressions can be used to estimate how impressions change in the future. These results may be useful in the field of neuromarketing for predicting long-term advertising effects.