# Questionnaires or Inner Feelings: Who Measures the Engagement Better?
## 1 Introduction  
Users' involvement [1] is crucial in all the product development cycle, including the early conceptual stages of product or service design. Participation in the system development process by representatives of the target user group impacts each stage of the product development cycle, influencing their contributions in an aggregate way, thus maximizing their effects [2]. In today's modern competitive market, user-centered design (UCD) [3] methods become more and more efficient in developing new consumer products. The UCD process is explicitly focused on the users, and consists of:  
- identifying the context of use and who are the primary users of the products;  
- specifying user requirements setting goals to make the product successful;  
- producing design solutions and prototype;  
- evaluating designs through usability tests to get users' feedback. Therefore, the term user-centered design, also known as human-centered design [4], indicates a precise design mentality focused on human needs. This approach originates from co-design [5], a widerange of creative techniques whose aim is to actively involve all stakeholders in generating ideas to support the process and to reach both immediate and longer-term benefits. The evaluation and quantification of users' engagement respond to this need, and, in particular, addresses the 4 th step, i.e., \"evaluating designs through usability tests to get users' feedback\". In this sense, the main contribution of this paper is to propose a novel methodology for measuring the student's engagement in a virtual learning environment, although it could fit the design of every type of product or service. According to [PERSON] [6], there are three distinct yet interrelated types of engagement in learning: behavioral, cognitive, and affective. Behavioral engagement is defined in terms of persistence, effort, attention, participation, and involvement conduct towards the learning activity; cognitive engagement refers to psychological effort to learn, to understand, and to master intended knowledge and skills; lastly, affective or emotional engagement [7] involves interest, happiness, boredom, and other feelings in learning processes. The more time students spend engaged during instruction, the more they learn [8]. First, researchers have studied and developed in-depth methods to measure students' engagement to increase it [9]. E-learning systems have been introduced to facilitate and enhance the learning process [10; 11]. The most popular methods of measuring engagement [12] can be divided into 3 categories, each of them with pros and cons. (1) Questioning methods: surveys, questionnaires, or self-reports. The interviewees describe their level of engagement by answering several open-ended or closed-ended questions in a set format [13]. Questionnaires are practical and affordable ways to gather data from a large audience, and they do not require the use of any instrument to perform the evaluation. Nevertheless, respondents may not be truthful with their answers, there is a chance that some questions will be left unanswered, and there is no way to observe facial expression, reactions or body language to fully capture the respondents' feelings. (2) Physiological methods: physiological and neurological sensor readings [6; 14]. Physiological measures such as galvanic skin response (GSR), electroencephalogram (EEG) [15], blood pressure [16] and heart rate can be used to evaluate students' engagement and alertness [17; 18]. These methodologies are alternative tools to provide feedback, but require specialized sensors and are difficult to use in large-scale studies. (3) Observational methods: analysis and interpretation of cues from face [19], body posture [20] and hand gestures [21]. Observation is a low-impact and flexible approach to collect data and can produce a mix of qualitative and quantitative data. It is often used in conjunction with other approaches in initial focus groups, interviews or surveys.