# Deep Learning for EEG-Based Preference Classification in Neuromarketing
## 2 Background
### Neuromarketing  
Traditional marketing approaches include surveys, interviews, questionnaires, and focus groups, in which consumers openly and consciously report their experiences and opinions. However, such traditional approaches cannot evaluate the unconscious side of the consumer behavior. Neuroscience has the potential to discern the unconscious motivations that influence the act of making choices. It has been reported that approximately 90% of data are processed subconsciously in the human mind [8]. In the field of neuromarketing and consumer neuroscience, the evaluation of the subconscious activities exposes the true preferences of consumers more accurately than traditional marketing research does. Furthermore, neuromarketing can reveal information regarding the consumer preferences/ratings that cannot be accurately determined through the traditional methods. This is because subconscious opinions play a key role in consumer decision-making. Traditional market research approaches fail to assess the subconscious activities in the consumer brain, which leads to an inequality between the results of the traditional market research and the real behavior of the consumers at the points of purchase [8].  
The term \"neuromarketing\" is derived by combining the prefix \"neuro\" and the term'marketing\", indicating the integration of two study areas: neuroscience and marketing [1]. Neuroscience is a field that examines the facets of the brain at the biological level and from a psychological perspective [2]. In addition, neuroscience has significantly enlightened the field of marketing, and the interaction between these fields assists in intuitive the consumer behavior [8].  
The term \"neuromarketing\" began to emerge organically around 2002. At that time, a few corporations, such as Brighthouse and SalesBrain, began offering neuromarketing studies and consultations, motivating the application of technology and knowledge from cognitive neuroscience to the field of marketing. Neuromarketing values the study of the consumer behavior from a psychological perspective [1]. Recently, several high-profile companies have begun exploiting neuromarketing approaches to assess the advertisements before introducing products to consumers [9]. This neuromarketing approach has gradually gained favor with brand executives in major corporations, such as Coca-Cola and Campbell's [10].  
Neuromarketing researchers aim to use neuroscientific procedures to exploit consumer behavior (i.e., requests, needs, and preferences) when shoppers purchase goods. This factor represents the researchers' primary motivation for examining the consumers' sensorimotor, mental, and effective feedback for products and advertisements through various modalities [9]. There are several neuromarketing modalities besides BCI, such as eye-tracking, galvanic skin response, skin conductance, facial coding, and facial electromyography. Each modality records different neural measure [11]. Eye tracking is used to determine eye locations and eye movement to grasp the consumer's attention and natural responses to marketing stimuli. Galvanic skin response measures the moisture activity, which is related to the emotional state. Electromyography is used to evaluate the physiological features of facial muscles. Facial coding measures emotional states through facial expressions.