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Many studies shown that high abandonment rate of assistive technologies and/or interactive systems may be important because no sufficient representation from potential users. Philips and Zhao (1993) related that almost one third of all the user’s assistive technologies were completely abandoned. This high rate of abandonment ascertained that a large percent of devices (assistive technologies, interactive systems, physical devices, etc.) are not meeting user' needs. Riemer-Ress and Wacker (1999) reported additional explanations such as environmental barriers dependent of the disability and also fear of technology. Sometimes low performance of interactive systems or their inability to adapt to new user’ functional abilities that are inevitably imposed by the development of impairment are also reported within the literature.
It is well established that the User-Centered Design (UCD) approach to design assistive and rehabilitation technologies might represent an important way to improve accessibility, usability, acceptability and appropriation.
The Norman’s model (Norman, 1986), (Norman, 2013) is a well-known conceptual model used for interactive system design. It helps the designers to understand the stages followed by the users when interacting with a system, and may incite them to involve explicitly the user in the design process. This model is generic and is centered mainly on only one person: the end ‘user of the interactive system.
However, the design of assistive and rehabilitation system for disabled people needs to identify the right stakeholders involved in the UCD for informing the design process and to express their needs, to report their behavior in the activity daily life, to acquire a mental model of the system as defined by (Norman & Draper, 1986). Disabled end users may have difficulties to express their needs, other stakeholders such as caregivers, family members, teachers, specialized educators, etc., have to collaborate in the different design stages (Marti & Bannon, 2009) (Markopoulos et al., 2011). More their needs have also to be taken into account as direct or indirect users of the future systems in the context of common activities with the disabled person. These stakeholders launch a working group called ecosystem.
Our definition of the ecosystem is the following: The ecosystem is defined as a subset of people present in the human environment accompanying him/her during one or several his/her daily activities. For example, the human environment of a child consists of his or her family, friends, teachers, caregivers and so on; but his or her ecosystem as part of a school activity is composed of the teacher, specialized educators, speech therapist, psychologist and his or her fellows. The initial Norman’s model does not consider explicitly such important aspect.
The paper contributes to Human-Centered Design in case of assistive interactive systems. To resume, our motivations are the following: in case of assistive interactive system design for different categories of disabled people (spoken and written disorders and behavioral disorders), the Norman’s model does not reflect explicitly the importance of the ecosystem in each user’s activity. Our experience in several projects shows that it must be adapted.
In consequence, this paper will report the participation of the ecosystem according with the different steps of the Norman’s model. An adaptation of the conceptual Norman’s model will be proposed. Two representative case studies will then illustrate the adapted Norman’s model. In both cases, despite different disabilities, users have communication difficulties. Both studies are also interested in two different phases in the Norman’s model. The first study focuses on the design step of prototypes, while the second focuses on the evaluation of an existing tool. These two studies thus show the crucial importance of the ecosystem whatever the design stage.