# Towards Detection of Interest Using Physiological Sensors
## 2 Methodological Choices and Research Questions
### The Nature of Interest
The researchers then studied differences in physiological measures following the viewing of the two categories of video clips in the participants. Here, the terms \"interest,\" \"attention,\" \"engagement,\" and \"boredom\" were used to describe the stimuli and/or the participants' reactions to the stimuli. [PERSON] et al. [30] described interest as one of eight basic learning emotions in their affective learning model. Interest was also regarded as an academic emotion, along with confidence, excitement, and frustration by [PERSON] in [31]. Other studies have investigated students' interest in learning in terms of positive emotions displayed in the classroom. For example, [PERSON] et al. [32] studied student interest in learning science by observing four emotions, namely happiness, fear, sadness, and calm. In a study by [PERSON] and [PERSON] [33], the authors assessed the level of interest while the subjects watched movies. The authors explained interest as a representation of how strongly an audio-visual experience attracts a viewer's interest. The rest of the reviewed papers, did not specifically define interest [34]. Rather, interest in these papers was described as an affective state [35; 36] or described in detail in terms of its different levels [37] and/or associated physiological patterns [38]. More details are given in the appropriate sections of this paper. Obviously, many of the objective studies presented here are not associated with or refer to an appropriate psychological or theoretical model. Many theories and models regarding interest development have been proposed. These models include, but are not limited to the four-phase model for interest development by [PERSON] and [PERSON] [13], the integrated model of interest development by [PERSON] and [PERSON] described in [3], the psychology of constructive capriciousness by [PERSON] [39], the model of domain learning by [PERSON] [40], and the person-object theory of interest [27; 41]. The lack of connection between physiological and psychological models, and the results obtained based on these models, may cause confusion with similar cognitive and emotional concepts. For example, the study by [PERSON] et al. [29] used interesting versus non-interesting video clips to assess participant's attention and engagement. Therefore, it is unclear if the observed physiological effects in this study were related to interest, engagement, attention, or all three parameters at the same time. In fact, as mentioned earlier, interest has been described as cognitive or emotional states, including engagement or pleasant tension. Furthermore, [PERSON] stated that interest is a construct with cognitive and emotional intrinsic qualities and values [42]. One possible way to distinguish interest from other states, e.g., engagement or attention, is to monitor its development rather than studying it as a single emotional or cognitive state. Therefore, it is advisable to suggest or provide evidence for links between physiological and psychological studies in order to establish an informative, well-established, and well-developed concept. However, as argued by [PERSON] and [PERSON], [PERSON], and [PERSON] [27; 43], one should not define or limit the meaning of interest to only one specific aspect in order to establish a common definition. Instead, one should develop a theoretical framework referring to different interest phenomena. Therefore, we provide the reader with an overview of the different perspectives regarding interest in this section. Although each model or theory is distinct from the others by different reasoning and arguments, the models still overlap in some areas, e.g., the impactof interest on individuals.