# Webcam Eye Tracking for Monitoring Visual Attention in Hypothetical Online Shopping Tasks
## 2 Literature Review  
There are a variety of techniques for monitoring human-computer interactions while visiting a website. On the server site, sever logs can be collected. On the client site, user behaviour can be monitored in more detail with mouse and event tracking. Mouse clicks and moves, scrolling, keyboard inputs or selecting, copying or printing content can be recorded and analysed [11]. Applications such as the e-commerce preference monitoring (ECPM) behaviour-tracking tool allow capturing a spectrum of online customer activities [12]. However, to obtain information about the website user's visual attention, eye tracking is an essential tool [13]. Traditionally, eye tracking devices based on infrared technology are used, either in the form of eye tracking glasses or remote eye trackers. They enable non-invasive eye movement recording under largely natural conditions with high precision and at manageable costs [14]. Besides applications, e.g., in medicine, psychology, learning, and reading research [15,16,17], eye tracking is widely used in marketing and user experience research [8,14]. However, the use of traditional eye trackers requires participants to visit an eye tracking laboratory [9] or researchers to visit participants to take the eye tracking recordings, resulting in time and travel costs and requiring organisational preparation [8]. In addition, the researchers have to handle the eye tracking devices and supervise each participant from the beginning to the end of an experiment, as they must at least start and stop the eye tracking recording. They also have to educate participants about potential (admittedly extremely rare) health impairments that might be triggered by the infrared eye tracking devices [18]. Another issue that emerged with the COVID-19 pandemic outbreak are pandemic-related recommendations and orders to avoid physical contacts. This, of course, also hinders eye tracking studies that require face-to-face contact between researchers and participants. An alternative to overcome the financial, logistical, and organisational challenges might be webcam-based eye tracking. The technology does not require any specific eye tracking equipment, only a webcam and software, which gives researchers access to a large number of potential participants who would be otherwise too far away [8]. Nowadays, a webcam is often already integrated into computer or laptop screens, so participants can take part in a webcam eye tracking study from home using their own equipment and without having to interact with a researcher face-to-face, avoiding health risks from infrared light and infection risks in times of a pandemic. However, existing webcam eye tracking solutions suffer from lower accuracy of the eye tracking data compared with traditional eye trackers [8; 19]. In addition, it is questionable if each participant can ensure optimal and reproducible experimental conditions, e.g., with regard to the quality of the webcam, the incidence of light on the camera and eyes, or the appropriate distance to the computer screen, without a researcher supervising the experimental procedure. Thus, the online approach raises some questions about the validity of the experimental process [9; 19]. Despite these challenges, webcam eye tracking is considered by various authors to be a promising technology for the future. This applies in particular to studies that primarily aim to determine which elements attract user's visual attention on a website, as long as extremely high accuracy is not required, e.g., if the elements are large enough and have sufficient distance from each other [8; 9; 20]. Visual attention is driven both by endogenous or top-down factors such as an individual's goals, preferences, expectations, task, cognitive load and mood and by exogenous or bottom-up factors that are beyond the individual's control such as visual salience, surface size or position of an object [7; 21; 22]. Which factors dominate in guiding visual attention are controversially discussed.