Research Article Forecasting Unplanned Purchase Behavior under Buy-One Get-One-Free Promotions Using Functional Near-Infrared Spectroscopy SuJin Bak , 1 Minsun Yeu , 2 and Jichai Jeong 1 1 Department of Brain and Cognitive Engineering, Korea University, Seoul 02841, Republic of Korea 2 College of Business Administration, University of Ulsan, Ulsan 44610, Republic of Korea Correspondence should be addressed to Minsun Yeu; minsunyeu@ulsan.ac.kr and Jichai Jeong; jcj@korea.ac.kr Received 28 June 2022; Revised 4 October 2022; Accepted 8 October 2022; Published 7 November 2022 Academic Editor: Jesus Peral Copyright © 2022 SuJin Bak et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. It is very important for consumers to recognize their wrong shopping habits such as unplanned purchase behavior (UPB). Te traditional methods used for measuring the UPB in qualitative and quantitative studies have some drawbacks because of human perception and memory. We proposed a UPB identifcation methodology applied with the brain•computer interface technique using a support vector machine (SVM) along with a functional near•infrared spectroscopy (fNIRS). Hemodynamic signals and behavioral data were collected from 33 subjects by performing Task 1 which included the Buy•One•Get•One•Free (BOGOF) and Task 2 which excluded the BOGOF condition. Te acquired data were calculated with 6 time•domain features and then classifed them using SVM with 10•cross validations. Tereafter, we evaluated whether the results were reliable using the area under the receiver operating characteristic curve (AUC). As a result, we achieved average accuracy greater than 94%, which is reliable because of the AUC values above 0.97. We found that the UPB brain activity was more relevant to Task 1 with the BOGOF condition than with Task 2 in the prefrontal cortex. UPBs were sufciently derived from self•reported measurement, indicating that the subjects perceived increased impulsivity in the BOGOF condition. Terefore, this study improves the detection and understanding of UPB as a path for a computer•aided detection perspective for rating the severity of UPBs. 1. Introduction Consumers have experienced fnancial problems such as excessive consumption, household debt, and monetary losses because of unplanned purchases [1]. Many studies have shown that reasonable consumption is difcult because unplanned purchase behavior (UPB) occurs emotionally or impulsively [2]. Many studies have reported that UPB can occur under situations that encourage people’s impulsive• ness such as price discounts and time pressures [3, 4]. UPBs are defned as a purchase of any item that consumers had not planned to purchase before entering the shops [5]. UPBs are increased by promotion strategies [6] such as price dis• counts, coupons, and money•back guarantee. Especially, “Buy•One•Get•One•Free” (BOGOF) is one of the most popular promotion strategies. A previous study found that over 53.3% of 192 respondents preferred BOGOF over other promotions [7]. Tis promotion strategy plays an important role in eliciting consumer’s UPBs. To assess whether consumers’ UPB is, there are tradi• tional research methods such as interviews, surveys, and questionnaires [8]. However, they rely on consumers’ subjective perceptions and memories [9]. Furthermore, there is still a lack of tools and equipment for empirically measuring UPBs. To solve this issue, there are recent studies that have reported empirical evidence for unplanned pur• chases through brain signal measuring equipment [10]. Tere are noninvasive equipment for brain measurements such as electroencephalogram (EEG) [11, 12] and functional magnetic resonance imaging (fMRI) [13]. Figure 1 describes the noninvasive brain signal measurement equipment that is harmless to the human body. EEG records voltage Hindawi Computational Intelligence and Neuroscience Volume 2022, Article ID 1034983, 12 pages https://doi.org/10.1155/2022/1034983