The influence of aesthetics on usability engineering

Sean Hägen, founder & director of research and synthesis, BlackHägen, shares his theories and methodologies to optimise human factors engineering for usability.

How a medical product’s impression enables usability has scientific premises in human factors/usability engineering (UE) and industrial design. Each discipline shares theories that, when harmonised, can become a method to optimise usability, which is ease of use and use safety. The importance and challenges in the relationship between medical device design, UE and the aesthetic development process significantly impact usability and delight. There are two theories that complement each other to create an applicable methodology: affordance and product semantics.

UE Research has documented the nature of a user’s choices and user interface behaviour, as it is influenced by aesthetics, specifically initial visceral impressions and intuitiveness of use. Consider, the apparent usability of a device may be just as important to the actual usability. The initial impression of a device and the user’s expectation for how it will function and meet their needs is often critical to safety and efficacy in the healthcare context of use.

These initial impressions can be characterised and planned for, via the theory of affordances. That is, a user’s perception of potential interaction with an object based on its properties, are referred to as its affordances. In this capacity it is a subset of product semantics. When designers are developing a user interface, the decisions and anticipation of successful interactions are related to aesthetics and are most crucial in the design process.

The industrial design theory of product semantics informs the design process and enables a self-evident user interface through the qualities of the device’s aesthetic, form, texture, colour, and metaphor. The aesthetic composition, or semantic, of a design does not literally explain what it does, rather, it influences how the user interprets it. When the two theories are integrated, product semantics can be a framework methodology to proactively enable the desired affordances in the design of a device.

The application of a perceived attributes methodology, where attributes of function and aesthetics define user perception of value, can align the cross-functional team in the development and the interpretation of requirements. This method can connect the two theories of product semantics and affordances into a cohesive approach to enable a meaningful and appropriate aesthetic by providing a common vernacular across development disciplines. A common challenge that usability engineering specialists have characterising user needs and user interface (UI) requirements is trying to understand and characterise intuitive use, or worse yet, "ease of use." Having a common definition of function, aesthetic and ultimately, value can help characterise such ambiguous requirements with a documented baseline.

Use-safety impacts the design from the perspective of regulatory objectives, engineering being the lead stakeholder. Ease of use impacts design from the perspective of marketing business objectives. However, the engineering stakeholders for regulatory objectives are not necessarily the same as those focussed on technology or usability. Use-safety is the responsibility of UE, which may be initiated as part of system engineering or implemented as part of quality engineering. 

Often the implementation of these varied agendas is translated into user interfaces by industrial design. The UI design is responsible for influencing the user to behave and use the device as intended by both the device manufacturer and the user. The connection of these disciplines and objectives is typically documented in requirements. This is where the deployment of a product semantics methodology, enabling intended affordances through a collaboration tool such as perceived attributes, can align all the designers’ interpretations of the requirements. 

Consider the UE process and the validation of the UI design. Formative studies typically identify tasks that have usability issues and many of those are characterised as not intuitive, requiring the design to be more user friendly. Those evaluations are purposely designed so that the user does not know how the device is intended to operate in order to expose usability issues and, by default, demonstrate intuitiveness. When UE report on usability issues, there is language used to describe the deficiencies. These can inform the development of the perceived attributes that, in turn, inform the product semantics.

Consider product semantics as a design language for optimising usability, aesthetic, shape, form, colour, and metaphor, which speaks to the end user and is open to their interpretation. Where the syntax is the affordance and the vocabulary is its perceived attributes informed from the UE process.