# Review of Studies on User Research Based on EEG and Eye Tracking
## 3 Indicators of User Research
### Experimental Paradigm  
In user research, eye tracking and electroencephalography are used to observe changes in users' physiological data in product use or objective environments. The combination of dynamic and static images and feelings is used as the observation object to explore the top-down and bottom-up processing methods in cognitive processing, in order to establish computational models or make quantitative predictions of visual processing. Classic paradigms of eye tracking experiments involving such scenarios include eye tracking paradigms, background cue paradigms, and object perception paradigms. Among them, eye tracking paradigms generally present scene stimuli to subjects, and require subjects to freely view the scene. During the subject's viewing process, their eye tracking information is recorded and then analyzed. The background cue paradigm is mainly based on visual search research, and aims to explore the effect of the scene background on the target search [39]. The object perception paradigm is illustrated in Figure 6. First, the name of the target object is presented to the subject, then a fixation point is presented, followed by scene stimuli; then, a mask composed of meaningless lines with a circle indicating the location where the target object appears on it is presented; and finally, the subject makes a judgment and records their reaction time [40]. Target location cues can appear before orafter the scene. If the location cue appears before the scene presentation, the reaction time recording begins after the scene presentation ends.  
The \"Go/Nogo experiment paradigm\", \"Oddball paradigm\", \"Flanker paradigm\", \"Stroop paradigm\" and their related variations are commonly used in ERP experiments. In the Go/Nogo paradigm, LRP (lateralized readiness potential) and N200 components are mainly focused on to explore the rules of cognitive processing. The Oddball paradigm is widely used, and is an experimental paradigm that produces ERP components such as P300 and MMN related to differences in stimulus probability; they have produced many subtypes [41]. Flanker is a research paradigm used to measure target stimuli and interference stimuli, while the Stroop paradigm is used to study the interference effect of emotional stimuli on cognitive processing.  
The current combination of EEG and eye-tracking research is mainly based on the Oddball paradigm. The Oddball paradigm refers to the continuous alternation of two or more visual or auditory stimuli, such as using the process of \"experimental instruction language--500 ms target picture/irrelevant picture--800-1200 ms random blank screen\" to study the subject's brain activity based on differences in stimulus frequency. This experimental process has similarities and complementarities with EEG and eye-tracking experiments, in terms of experimental objects and processes [14]. Integrating multimodal physiological signals related to visual feature processes can obtain more convincing research data, which are very suitable for the quantitative analysis of combined EEG and eye-tracking methods in user research.