**2. Background**

In this work, we adopted the PSD model [18] as the theoretical framework for our research, and the SQ model [9].

## **2.1 The PSD model**

The PSD model [18] is a recent conceptualization for designing, developing and evaluating persuasive systems. It consists of (a) the premises behind any persuasive system, (b) the persuasion context and (c) the persuasive software system features. Hence, according to the PSD model any persuasive system is based on eight premises detailed in [18] and listed here: P1: Useful; P2 User-friendly; P3: Unobtrusiveness; P4: Open for transparency; P5: Cognitive Consistency; P6: Incremental; P7: Information technology partiality; P8: Direct and indirect routes to persuasion.

The analysis of the *persuasion context* consists of looking into (1) the intent, (2) the event and (3) the strategy. The event comprises the use situation, user's characteristics, technological platform and environment. The strategy includes the message itself and the route to be used to achieve a goal.

The PSD model describes persuasive software system features grouped in four categories: (i) The **primary activity support category** focuses on supporting the activities that lead to achievement of the BCSS goals. These activities include

<sup>1</sup> Systems in which software interacts with other software, systems, devices, sensors and people [14].

### *Negative UX-Based Approach for Deriving Sustainability Requirements DOI: http://dx.doi.org/10.5772/intechopen.96535*

reduction, tunneling, tailoring, personalization, self-monitoring, simulation and rehearsal. (ii) **Dialog support** refers to techniques/mechanisms to motivate users to use BCSS. This category includes praises, rewards, reminders, suggestions, similarity, liking and social role features. (iii) The **credibility category** relates to how to design a system so that it is more credible and thereby more persuasive. This category includes the following features: trustworthiness, expertise, surface credibility, real world feel, authority, third party endorsements, verifiability. iv) **The social influence category** describes how to design the system so that it motivates users by leveraging different aspects of social influence. The features that belong to this category are: social learning, social comparison, normative influence, social facilitation, cooperation, competition, recognition.

According to the PSD model, a behavior change can be divided into three categories:


The outcomes of these C, B and A-Changes are the formation, alteration or reinforcement:


### **2.2 The SQ model**

The SQ model [9] is defined in terms of four *sustainability dimensions*: (i) *Technical dimension* addresses the long-term use of software-intensive systems and their appropriate evolution in an execution environment that continuously changes. (ii) *Economic dimension* focuses on preserving capital and (economic) value. (iii) *Social dimension* focuses on supporting current and future generations to have the same or greater access to social resources by pursuing generational equity. (iv) *Environmental dimension* aims at improving human welfare while protecting natural resources. For software-intensive systems, this dimension aims at addressing ecologic concerns, including energy efficiency and ecologic awareness creation.

Each dimension is characterized by a set of *Quality attributes*, which can be interdependent. Such dependency can be of two types: (i) it is *inter-dimensional* if it relates a pair of quality attributes defined simultaneously in two different dimensions (e.g. security defined in the *technical* dimension can influence security in the *social* dimension); and (ii) it is *intra-dimensional* if a dependency exists between two different quality requirements defined within the same dimension (e.g. in the *technical* dimension, security may depend on reliability).

#### *Software Usability*

Our SQ model supports the identification of sustainability design concerns, and the quality assessment of software architecture. The list of measurable attributes of the SQ model and corresponding contributions to the four dimensions can be found at [9], which has been empirically evaluated [19, 20].
