# Towards Detection of Interest Using Physiological Sensors
## 2 Methodological Choices and Research Questions  
Here, we review all the related peer-reviewed articles that address interest or its levels using physiological sensors. Specifically, we reviewed recent work written in English from the past last 13 years, comprising articles written from 2003 until 2019. We intend to include the earliest studies with high impact on the current research and to precisely discuss and analyze recently published innovative findings and insights.  
A quick review of the literature indicated that many studies address interest subjectively, but very few studies with objective support. Many psychological, educational, and social studies lack support from neuroscientific research that examin the way interest modulates physiological parameters. Encouraging researchers to carry out physiological studies would lead to the publication of research that would not only support, but also explain and clarify ambiguities regarding interest, such as interest as a cognitive construct or emotional state, and the development of interest over time. These studies would also lead to a better understanding of the two common types of interest (personal and situational) and would assist future researchers in discovering solutions to reinforce the presence of either or both of these two types of interest. This would, in turn, improve student learning, well-being, and goal accomplishment.  
Hence, this review focuses on presenting research work that examines the physiological effects of interest using the following physiological parameters: electroencephalogram (EEG), electrocardiogram (ECG), heart rate (HR), galvanic skin response (GSR), eye movements, and pressure seat. We aim to answer the following research questions in this review:  
RQ1: What basic definitions of interest do the authors refer to?  
RQ2: What is interesting about the different levels and types of \"interest\"?  
RQ3: What are the physiological sensors that have been used so far to assess interest and what are their associated patents?  
RQ4: What are the possible effects of differences in experiment design, including differences in stimulation, number of subjects, age of subjects, and length of experiment, on the experiment output?  
RQ5: How can we improve research related to the detection of interest using physiological sensors?  
The terms used in our search included\" situational interest detection, \"detection of interest using EEG\", \"individual interest detection\", \"detection of interest using eye tracker\", \"detection of interest using ECG and HR\", \"interest in academic content\", \"customer interest detection using physiological sensors\", \"emotion detection using physiological sensors\", and \"recognition of interest. The main purpose of this paper is to review objective studies on interest. Hence, subjective studies are only discussed to form a basis for the understanding of the physiological (objective) research. Physiological studies were included or excluded based on the following criteria: (i) written in English, (ii) published between 2003 and 2019, (iii) the study addressed the detection of interest or emotions or cognition leading to the detection of interest, (iv) used physiological sensors, (v) had a valid stimulation paradigm to trigger interest, (vi) resulted in the detection of interest or a new output. Studies that did not fulfill these criteria were excluded. The success of each of the studies discussed here was measured by assessing the experiment's output. These outputs included the participant's grades [3], if applicable, the participant's self-report, and the classification of interest as suggested by the physiological parameter of interest. We included nineteen (19) studies in our review. The methodological choices and research questions are summarized in Figure 1.