Interaction Design

One of the barriers to the application of task analysis to interaction design has been the lack of a tool to enable rapid construction of task descriptions with accompanying elegant task diagrams. TaskArchitect enables interaction designers to rapidly sketch task sequences and review them on the fly with end users through a variety of task diagrams. That’s just the start. The ease of defining what information to collect means that interaction designers can develop their own custom tools to support their design process.

Two examples of how different experts have developed task analysis to support interaction design are described below. Stammers and Astley in 1987 illustrate how task analysis, originally conceived 20 years earlier for training applications, could be applied to interface design. The paper shows how the collection of information requirements for tasks can support design decisions.

A further 20 years later, Adriano Galvao applied task analysis initially to industrial design, then more broadly to the topic of interaction design. His Function Task Interaction (FTI) Design Method integrates task analysis, product affordances and product functions to produce a sophisticated and easy to use design tool.

TaskArchitect supports both of these approaches and enables designers to develop and apply their own approaches, quickly and elegantly.

Stammers and Astley (1987)

Their approach focused on the information required to carry out tasks:

  • The operations (task elements) the human has to perform
  • The conditions and temporal ordering under which they are performed
  • The information flows to and from the interface
  • The information that is prerequisite to the operator being able to perform the task
  • The kind of task for which the information will be used

This information, supplemented by notes about the task, provides a foundation for design decisions. This perspective on design, to leave the design decision to the designer yet provide a sound analytical foundation, fits with Norman’s account of HCI’s needs. Their approach has much in common with techniques that have become more popular, recently such as the application of use cases and the perspectives applied under the banner of information design. Web design, application design and customer experience design can all benefit from this foundation.

Stammers, R. B., & Astley, J. A. (1987). Hierarchical Task Analysis: Twenty Years On. In E, D. Magaw (ed.) Contemporary Ergonomics, Taylor and Francis, London, pp135-139.

Function Task Interaction (FTI) Design Method (2006)

Successful designs are based on a deep understanding of users and their activities. Task analysis is an effective way to decompose activities into subtasks and understand the possible ways users fulfill their needs.

The FTI methodology gives designers more control over their designs by linking users' tasks with product functions in order to identify user-product requirements during the early stages of product development. The method utilizes the concept of affordances as an instrument for understanding the relationships between technical functions and user tasks. The outcomes of the method include:

  • Exploration of users’ tasks and subtasks
  • Investigation of user-product interactions
  • Indication of affordance demands on product functions
  • Introduction of visual means for representing functional affordances in product architecture
  • Exploration of solutions based on affordance attributes

The first step in the FTI methodology includes the collection and organization of users' tasks based on Hierarchical Task Analysis (HTA). The goal is to clearly describe what the user intends to do. Tasks are broken down into hierarchical descriptions with several levels of abstraction, from general tasks to specific subtasks. TaskArchitect can be used in this step as a central tool to capture and organize the user data and as a conduit to the following analysis tools. The task information is documented using a "verb-object-qualifier" format. Concurrently to the task analysis, the overall functions of the new device are defined and decomposed into sub-functions that delineate design problems to be solved. Functional Modeling approaches may be used at this stage with the information captured in [company_short.

The second step involves the exploration of “must have” relationships between users and the product, or affordances. The process of defining these affordances consists of three sub-steps:

  • Understanding and expressing user needs in terms of affordances
  • Creating a generic affordance list
  • Prioritizing affordances

The output of this phase is a generic list of affordances prioritized by user groups. The list emphasizes product attributes that should receive greater attention during product architecture, based on the utility each provides for a particular user group.

In the third step a Design Structure Matrix relates the users' tasks and the product functions. The matrix has users’ tasks as the column headings, and product functions from functional model decomposition studies as the row headings. The strength of the FTI matrix lies in the visualization of the interaction points between tasks and functions.

Interaction here refers to functions that are required to engage in a certain user task and vice-versa. The relationships from technical functions to user tasks specify which product attributes are needed, while the relationships from user tasks to technical functions specify where affordances can aid users in accessing them. Based on this information, designers can explore provisional design options for future devices in the final step four.

Galvao, A. and Sato, K. Affordances in Product Architecture: Linking Technical Functions and Users' Tasks, in Proceedings of 17th International Conference on Design Theory and Methodology, ASME, Long Beach, CA, 2005.
Galvao, A. and Sato, K. Human-Centered System Architecture: A Framework for Interpreting and Applying User Needs, in Proceedings of 16th International Conference on Design Theory and Methodology, ASME, Salt Lake City, UT, 2004.
Swanson, E., Galvao, A. and Sato, K. A Framework for Understanding Contexts in Interactive Systems Development. Proceedings of 7th World Conference on Systemics, Cybernetics and Informatics, FL, USA, Vol. 4, pp.405-408, 2003.

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