'What is intuitive design?'

06 February 2017

Medilink member

By Dan Simmons, Human Factors Consultant, CCD

If a user describes a product or system as intuitive it is among the highest praise they can offer, but what does being intuitive actually mean? Ironically, people’s definition of intuitive is, well, intuitive, as they struggle to define the term in a specific, meaningful way. In effect though something is intuitive when users understand it without use of reason, experimentation, assistance, or special training. For such intuition to be possible requires prior knowledge, from experience in the real world. So, for example, if something looks like a push button, we know from the real world that we can push it to make something happen. 

The challenge for designers is that everyone has a different background, experience or expectations, and what is intuitive to one person may not be to another. To design products that feel intuitive for most users we first need to understand what intuition is and that is where human factors practitioners bring a different dimension to the design process by suggesting an approach that is based on human behaviour.

Complex products that you have been using for a long time can feel intuitive simply because you’ve had them for a long time and have got used to using them. New and seemingly simple products can feel very unintuitive because you don’t have any knowledge of how to use them. Confusing isn’t it? Yet, by understanding human factors designers can create products that feel intuitive from the outset. With a new product, there is always a learning curve….the shorter the better.  If human factors have not been considered, and it appears complex, the new user may have to process too much new information, cognitive overload can occur, information will get lost and a feeling of discomfort arises. The user will experience this as un-intuitive. Therefore, it is essential for designers to create products in which the amount of new information does not overwhelm the user.

In processing information, our brains are subject to three types of demands, or loads: cognitive (including memory), visual and motor. Each demand requires a different amount of mental effort. Trying to remember something or do a mental calculation – both cognitive loads – requires the most mental effort. Users therefore tend to want to keep things as they are, especially if it takes a lot of mental energy to change them. As we use up mental effort, our attention span lapses. It takes less mental effort to recognise something than it does to recall it from memory. Icons or prompts are useful in this regard. We also lose attention if too little mental effort is required. We have a fundamental drive to seek out information, and this concept of cognitive load suggests that a medical product design that is too plain won’t hold our attention. A design that is too complex will overload us, and too much choice inhibits decision-making. Finding the right balance is the key to effective medical product design.

When we interact with a surgical tool, medical device, lab instrument or indeed any object, our first impression will most likely be visual. We’ll see the object and then begin to make sense of it. What we perceive visually is not just what the eye physically sees; visual stimuli are then interpreted by the brain. The importance of the visual system to medical products is in understanding that we make connections even when information is missing. Considering Instructions for Use, how visual information is arranged and grouped will influence how the user interprets and understands the product and how easy or difficult it is to use.

Although users' first experience of a new product is through vision, their normal reaction is to want to handle it. Usability testing investigates not just the visual impact, but also what happens when they feel it. Our sense of touch has significant influence on how we judge things and our reactions to them. If we hold something warm, we trust it has been prepared. If we hold something cold we question it. This is referred to as the “priming” effect. Designers can tend to focus primarily on the visual aspects of the design, but it’s important to consider the tactile and aural as well. Warm or cold, heavy or light, rough or smooth – all influence our opinion.

Medical product design has a lot to do with developing devices with characteristics that make them easy to understand and to use. To do this effectively, designers must understand perception and cognition: how users sense the world, how those sensations are interpreted by their brains and how they think about and act on what it is they perceive. Much of the design process is spent considering how users will interact with the device that is being designed. By knowing how we sense, interpret and act on information in the world around us, medical product designers can be deliberate in providing cues that enable devices to be operated intuitively, confidently and safely.

The function of a medical device is of most importance. The device must work as intended, no questions asked. Designing a medical device in a way that clearly shows the user how to operate it must employ knowledge of cognition as a basic tool. Each of us have developed mental models of the world that we refer to when we encounter novel situations. Our mental models guide how we perceive, think, feel, decide and act. The key to designing an intuitive medical product lies in aligning the design with the user’s mental model of similar objects and visual cues present on the device.

It is important that medical product designers do not make assumptions about users. What might be obvious to you as the designer might not be obvious to those using what you’ve designed. People will always make mistakes. It’s impossible to design a perfectly fail-safe system. The approach to take is to anticipate as much as possible the mistakes that people might make and where possible design those mistakes out. Performing a failure modes and effects analysis (FMEA) is one way of identifying cognitive errors that users could make. Indeed, FMEA or similar procedures are required for medical devices as part of the FDA’s design control regulations. A common pitfall with FMEAs is that they have been written in a way that identifies potential failures in the devices that are essentially mechanical.

A successful FMEA is one that has used Human Factors knowledge to identify cognitive errors from the users’ perspective, rather than the devices. It understands the potential user group and identifies and attributes biases and perceptions that may influence how a device is used, or indeed misused.

To further understand intuition, we must also understand the drive and motivation of the user. Though we learn to hide it well, at the most basic level we all harbour doubt, fear, insecurity and a sense of incompleteness. To counteract those feelings, we are drawn to objects that reflect our view of our ideal selves. If you see yourself as intelligent, competent and serious, you’ll be attracted to things that embody those characteristics. We are also motivated by progress, mastery and control. Small signs of progress can have a big effect. Providing feedback is especially important here as that lets the user know that they are progressing along the right path. The closer we are to a goal, the more we focus on what’s remaining and the less we think about what has already been accomplished. And the more we focus on what’s left to do and not on what’s already been done, the more motivated we are. This creates a positive feedback loop. The user will be more engaged and their engagement will promote a positive user experience, which will encourage a feeling of intuitiveness.

Understanding cognitive psychology enables medical product designers to develop products that are intuitive to use and that appeal to the target user population. Knowing how we sense and make sense of things – how we see, understand and decide – is the essence of good medical product design.

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