What is intuitive design…part 2

In part 1 of this blog on intuitive design we discussed how perceptions and experience vary so much between individuals.  The role of human factors in the design process is critical in trying to understand this variability.  This is especially true in the design of products like medical devices.

In this second part, we explore some of the details around psychology and behaviour and how these impact the design process.


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.

Seeing and intuitive design

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.

How we’re influenced

We have been involved in a great number of usability tests and experiments and although users first experience of a new product is through vision, their normal reaction is to want to handle it. We investigate not only by seeing, but also by feeling. 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.

How we understand

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.

What motivates us?

To help further understand intuition, we must understand what the drive and motivation of the user is. 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 they manipulate the product, provide signals that let the user know that they are progressing along the right path.

The closer we get to a goal, the more motivated we are to continue. In one study, for example: people were given loyalty cards for a cafe. Some cards required 5 stamps to get a free breakfast. Other cards required 7 stamps but two stamps were already on the card. In both cases, subjects needed to get 5 stamps but those who got cards that already had progress toward the goal filled up their cards faster. 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.

In Summary

Understanding cognitive psychology will enable medical product designers to develop products that are intuitive to use and that appeal to the identified 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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