Human perception is inherently multi-sensorial involving five traditional senses: sight, hearing, touch, taste, and smell. In contrast to traditional multimedia, based on audio and visual stimuli, mulsemedia seek to stimulate all the human senses. One way to produce multi-sensorial content is authoring videos with sensory effects. These effects are represented as metadata attached to the video content, which are processed and rendered through physical devices into the user's environment. However, creating sensory effects metadata is not a trivial activity because authors have to identify carefully different details in a scene such as the exact point where each effect starts, finishes, and also its presentation features such as intensity, direction, etc. It is a subjective task that requires accurate human perception and time. In this article, we aim at finding out whether a crowdsourcing approach is suitable for authoring coherent sensory effects associated with video content. Our belief is that the combination of a collective common sense to indicate time intervals of sensory effects with an expert fine-tuning is a viable way to generate sensory effects from the point of view of users. To carry out the experiment, we selected three videos from a public mulsemedia dataset, sent them to the crowd through a cascading microtask approach. The results showed that the crowd can indicate intervals in which users agree that there should be insertions of sensory effects, revealing a way of sharing authoring between the author and the crowd.

Crowdsourcing arose as a problem-solving strategy that uses a large number of workers to achieve tasks and solve specific problems. Although there are many studies that explore crowdsourcing platforms and systems, little attention has been paid to define what a crowd-powered project is. To address this issue, this article introduces a general-purpose conceptual model that represents the essential elements involved in this kind of project and how they relate to each other. We consider that the workflow in crowdsourcing projects is context-oriented and should represent the planning and coordination by the crowdsourcer in the project, instead of only facilitating decomposing a complex task into subtask sets. Since structural models are limited to cannot properly represent the execution flow, we also introduce the use of behavioural conceptual models, specifically Unified Modeling Language (UML) activity diagrams, to represent the user, tasks, assets, control activities and products involved in a specific project.