This thematic issue addresses natural interaction in Intelligent Environments (IEs). IEs are distributed network of intelligent devices that are sensitive, adaptive and responsive to the presence of people. Such environments are as varied as the places people inhabit encompassing settings such as homes, classrooms, offices, factories, transport, cities and online virtual worlds. These environments will adapt themselves to the user and even anticipate on user needs. Systems in IEs usually have three basic characters: pervasive, natural interaction, and intelligence. This thematic issue aims to explore how to use cutting edge technologies to provide one of the characters of IEs —natural interaction. The combination of human specific communication modalities such as speech, handwriting, and gesture, emotion, as well as the possibility to personalize to user needs play a major role in the design of novel applications and services. Papers submitted should explore questions such as: What are the natural interactions with applications in IEs? Which modalities are best suited for different devices and tasks? How to provide multi-modal interactions? How the system adapts with the intuition and preferences of its users? How the system supports interactivity based on the continuous interpretation and processing of tasks, activities and contexts? How to provide responsiveness to the user? How can we use user-centred design in IEs? How to improve user experience? What are the evaluation items of natural interaction systems in IEs? Areas covered by this special issue include, but are not restricted to:

Localization/navigation systems suitable for AAL, based on different sensing modalities
Human Computer Interaction in IEs
User preferences and user modelling
Wearable sensors in IEs
the Internet of Things
Context awareness in IEs
Ambient Intelligent
Signal processing for interactions (speech, facial expression, gesture, bio-signals…)
Multi-modal data fusion for interactions in IEs
Learning and reasoning algorithms for IEs
Agent Platforms
Ubiquitous Computing
Mobile devices and mobile agentsNatural interactions in Smart Cities (for tourism, transportation, smart buildings…)