# Towards Detection of Interest Using Physiological Sensors
## 2 Methodological Choices and Research Questions
### The Nature of Interest  
Interest has been extensively studied in the last decades from different perspectives and based on expanded empirical and theoretical approaches. There is probably no uniform definition for interest. However, it is accepted that interest is \"a construct that characterizes a person's special relationship with an object (contents, topic, special subject, object domain, etc. )\" in the psychological, sociological, and educational domains [10]. According to many researchers, namely, [PERSON], [PERSON], and [PERSON], focused attention and/or engagement with a specific content reflect interest in the characteristics of that particular content or object [11; 12; 13]. [PERSON] et al. [14] considered interest to be \"both a psychological state of attention and affect toward a particular object or topic, and an enduring predisposition to reengage overtime\". [PERSON] [4] described interest as a facet of human motivation and emotion and suggested using interest to solve practical problems in learning, education, and motivation. In fact, many studies have shown that interest enhances learning (for a summary, see [5; 15; 16]). [PERSON] [17] described interest in an object or a topic as \"being engaged, engrossed, or entirely taken up\". Furthermore, interest has been discussed by many researchers in connection with individual states, e.g., emotions by [PERSON] [18], attention by [PERSON] and [PERSON] [19], curiosity by [PERSON] and  
Figure 1: Methodological choices and research questions. [PERSON] [20], flow by [PERSON] [21], and \"a thinking state, rather than an emotion\" by [PERSON] [22]. Although there is a valid justification for each consideration, studying interest as related to only one of these phenomena narrows its meaning. [PERSON] and [PERSON] [23] have stated that emotions consist of three different components: physiological response, behavioral expressive response, and subjective experience. Interest appears to have these components: it encompasses a subjective experience as described by [PERSON] [24], physiological and behavioral expressive responses associated with increased cognition, activation, and concentration, and approach-oriented action [4; 18; 25]. These arguments support the idea that interest has both affective and cognitive components. [PERSON] [6] has suggested that interest involves affect when it is initially triggered, which makes it appropriate to consider interest as an emotion at this stage. Interest is then integrated into one's cognition as it develops [13; 26]. [PERSON] [27] studied interest as an independent variable such as certain aspects of learning outcomes, dependent variables such as academic achievement, or hypothetical mediators such as attention and emotional experience. He also discussed the relationships between situational and individual interest, which are widely accepted as different types of interest (for a review, see [3]), and learning outcomes. This will be discussed thoroughly in the next section. This brief review highlights the variety of publications establishing or studying the numerous meanings of interest. Nevertheless, the studies outlined here generally agree that \"interest\" is a multidimensional construct, i.e., it has both emotional and cognitive components [28]. Establishing that interest has both emotional and cognitive components is necessary to assess the feasibility of different methods and sensors used to measure interest in the physiological studies that will be discussed in the following sections. Here we will briefly review studies discussing interest as a physiological construct to explore differences in addressing interest in different domains. [PERSON] et al. [29] used interesting and non-interesting video clips to assess the levels of attention and engagement in study subjects. They used interesting clips in order to keep viewers attentive and engaged with the content presented. Non-interesting clips were intended to induce boredom in the subjects and to reduce attentiveness.