How the ‘Illusion Delusion’ Threatens Intuitive Design and Hurts Your Business
Don’t be fooled – our basic cognitive processes are far more robust and trustworthy than some designers would have you believe. And designing products that speak to these basic processes does not simply guarantee usability – it’s good for business too
✎ By Rune Nørager, Senior Human Factors Specialist. March 2022
Key takeaways from this article:
– Illusions tell us little about how our brains normally work
– Our basic visual and spatial cognitive processes are actually very reliable at tapping into the world
– There is a strong business case for designing products that are designed for these virtually unlimited resources
Our Senses Have a Firm Grasp on Reality - If We Let Them
Our senses can’t be trusted and our brains are easily fooled. We know this thanks to illusions that show we can’t always accurately judge depth, size or colour, for example. But what does this mean for design? Does it mean that our experiences of the world are so different that you can’t expect people to share the same intuitive experience of a product?
Figure 1. In the checkerboard shadow illusion, tiles A and B appear to be different shades of grey, but are in fact identical. This illusion is widely used to demonstrate the apparent fallibility of our senses. But we shouldn’t take it so seriously – it is cleverly designed to trick our senses.
No. Illusions are actually extremely marginal phenomena that overemphasise our cognitive limitations and say very little about how we normally experience the world.
Our brain has actually evolved a range of different cognitive processes, over millions of years, which enable us to effectively and accurately tap into the world around us.
Some of these cognitive processes, like our visual and spatial skills, work quickly and unconsciously to provide us with accurate knowledge about the world under almost all circumstances. Carefully crafted illusions, like the checkerboard illusion in figure 2, carefully trick these basic processes by limiting our natural exploration of the world.
Others, like our conscious and intellectual processes, can kick in as backup when these basic cognitive processes break down under extreme circumstances – for example when they are presented with carefully crafted illusions (see the checker shadow illusion in figure 1 and the Ames Room illusion in figure 2). We use these processes to ask questions, logically process problems and actively learn.
At Design Psychology we help to design products that fit how our senses and brains actually work – for the full set of cognitive processes. Because when it comes to usability, the ultimate hallmark of intuitiveness is that it matches the way that we work in the natural world. It doesn’t just create better products, it’s a far better business case.
I’ll unpack these arguments in a little more detail below.
The Brain is Not a Computer
There was a time when psychologists and computer scientists thought of our brain as a type of computer – it collects sensory information about the world, processes it to create a representation of the world, which we then use to take action.
Some designers have internalised this paradigm of the brain as a computer that processes information. So if the information it receives is faulty – like the experience of an illusion – it can’t take the right action.
The solution that they propose is to design in a way that expects users to spend time learning how to interact with products. Because if we see the world differently, then we we cannot trust that a single design will be understood by all users. That’s why they argue that we should design primarily for our conscious and intellectual processes – the human equivalent of a computer processor.
But you should be wary of this claim. It’s the ‘illusion delusion’, and it will only result in sub-optimal products.
Tapping Into Reality
We now know better – that many of our basic cognitive processes work automatically without any need for conscious processing. It’s more like we are tapping into the world fluidly, quickly and unconsciously.
And while our conscious cognitive processes are powerful, they are slow, limited and fragile – so they require plenty of time, concentration, and protection from distraction. We place a high cognitive burden on the user if we expect them to always interact with the product using these ‘backup’ conscious cognitive processes.
This hardly an optimal cognitive state for the user to be in, if you want a user to interact with a product fluidly and intuitively. It only results in counter intuitive design and unhappy users who struggle to develop a strong relationship to the product – both threaten your business.
Illusions are designed to make us fail
Figure 2. The Ames Room illusion is carefully designed to trick our senses. The effect is shown in the top middle panel – people appear large when they stand in one corner but small in the other. This can only be accomplished by restricting our senses – like a straitjacket restricts our movement – so we cannot detect that the room is not a square box, but actually much deeper one one side than another. This relates closely to design: Does your design put users in a straight jacket, or does it empower them to function freely?
It’s not that illusions don’t work. Take a look at the Ames Room illusion in figure 2. People appear to be larger when standing on the right than on the left.
Like many illusions, it seemingly demonstrates our cognitive limitations that prevent us from experiencing the world accurately, or in the same way as each other.
But illusions are not a useful model for how we normally interact with the world. Illusions are designed to make us fail, and it takes a lot of careful work to trick our perception. They do this by limiting the behavioural mechanisms we normally use to tap into the world. It’s like putting our brain in a straitjacket and poking out one eye – it’s simply not fair!
An illusion is really hard to make exactly because our senses are so robust.
Figure 3. A demonstration of the Ames Room and how the illusion instantly disappears the moment we are allowed to function naturally and freely explore the scene. The point is that we, as designers, should ensure that our natural grip on reality is supported - even when we design abstract realities like graphical user interfaces. This requires a deeper appreciation of perceptual psychology than what designers reflect when they celebrate illusions as evidence of our fallibility.
Take another look at the Ames Room. The world does not normally present us this type of half-baked static information. Firstly, it presents us with carefully manipulated contextual information to impede us from accurately judging the size of the two people. And secondly, we are unable to view the illusion from another angle – we are fixed in place.
Instead, the real world normally presents us with dynamic information. For example, if we want to understand the size and depth of objects in space, we don’t do this by standing still. We get a better view by physically moving our bodies and our line of sight. In the real world even the slightest movement or nod of the head reveals robust and reliable information. In the video below, figure 3, you can see how the illusion collapses once the camera is moved from its fixed position mimicking or own movement to gather robust information.
This is just one example of the many ways that our brains naturally, effortlessly and intuitively tap into the world around us - if allowed to by design.
Intuitive Design Makes Good Business Sense
A well-known example of designing for our basic and robust perceptual and cognitive resources is the iPhone. What is less well-known is that much of the "human factors technology" was existing re-purposed technology that goes all the way back to Walt Disney and his team of animation researchers. At Design Psychology, we "re-purpose" psychological insights in the same way to help our clients design products that support our basic human skills to achieve truly intuitive use and a superior user experience.
Of course, we cannot overlook the importance of cultural context in design. There will always have to be some learning that takes place. But our basic cognitive resources are universal across all human beings, which means we can disregard differences in skill, IQ and gender. They also have virtually unlimited resources compared to more intellectual and conscious resources, and rarely break down.
That’s why there’s a strong business case for understanding how we are already fundamentally integrated with how the world works at large, and using it to underpin a design foundation – this is the approach we take at Design Psychology.
Doing so is a profound recognition and respect for how amazing it is that animals and human beings have adapted to tap into the deepest layers of the physical reality we live in. It’s an integration that has taken five billion years.
So, if a product isn’t working as intended, don’t blame the brain. Blame a faulty understanding of how to tap into the brain’s incredible abilities – blame the illusion delusion.
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If you want to learn more about the Design Pscyhology approach to design please reach out to:
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Rune Nørager
+45 4041 4422
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