At MacMartin, we believe effective design starts long before the visuals hit the page. It starts with people – how they think, feel, and behave. If we want to influence behaviour, we need to understand it first. Design psychology gives us the tools to do that.
Here’s how we use behavioural science to shape design that not only looks good – but drives real, meaningful change.
1. Start With Behaviour, Not Aesthetics
Good design isn’t just about what looks nice – it’s about what works. That’s why we begin with behavioural insight.
One of the models we often use to guide this process is COM-B, which helps us understand the building blocks behind any human behaviour:
Capability, Opportunity, and Motivation shape Behaviour.
Put simply, capability is about whether someone has the skills, knowledge, or mental resources to take action. Opportunity looks at whether the environment around them supports that action – are there barriers in the way, or is it even possible in their current setting? And motivation is about desire – whether someone actually wants to do it and sees value in making the change. If even one of these elements is missing, the behaviour is unlikely to happen.
Before jumping into creative solutions, we ask:
- What’s stopping people right now?
- What would need to change for them to take action?
Once we understand what needs to shift, whether that’s mindset, environment, or emotion, we can design more effectively. Real change doesn’t come from forcing behaviour. It comes from making the desired action feel natural, possible, and worthwhile.
2. Use Human Shortcuts (aka Cognitive Biases)
People don’t make decisions purely rationally. We use mental shortcuts and biases that help us act quickly, even if we’re not always conscious of them.
Great design leans into these, not against them.
Some of our favourites:
- Loss aversion – People fear losing more than they value gaining. So, show them what they’ll miss if they don’t act.
- Social proof – individuals tend to follow the crowd. Highlight how others are already on board.
- Authority – Credible voices carry weight. Use trusted sources or endorsements.
- Scarcity – Limited time or quantity adds urgency. But be genuine – people can smell fake pressure a mile off.
3. Design for the Brain, Not Just the Eye
Visual psychology helps people process information and make decisions quickly. That’s key when you’re competing for attention.
Here are a few principles we apply:
- Hick’s Law – The more choices, the longer it takes to decide. Less really is more.
- Gestalt Principles – Our brains love patterns. Group elements so they’re easy to scan and understand.
- Anchoring – Start with a high-value option to set a frame of reference. It makes other options feel more attainable.
- Confirmation bias – Reinforce what people already believe. It feels reassuring – and it builds trust.
4. Make Action Feel Natural and Worthwhile
For people to take action, it needs to feel easy, rewarding, and timely.
Start by reducing friction. If something feels like a hassle, like too many steps, confusing forms or unnecessary barriers, most people will abandon it. So we should simply the process by cutting down on clicks, removing clutter, and minimising cognitive load wherever we can.
Next, make the experience visually appealing and worthwhile. Bold, clear design draws attention. Rewards, whether real or perceived, make the effort feel valuable. If it looks good and feels good, people are more likely to engage.
Social influence also plays a big role. People tend to follow the lead of others, especially those they relate to. So, we show them that others are already taking part. Testimonials, stats, even subtle cues can build that sense of collective momentum.
And finally, timing is everything. Catch people in the right moment, like when they’re already thinking about the topic or most open to change, and the message lands far more effectively. Design should feel like it shows up just when you need it.
Would you like to learn more about how we utilise design psychology?
5. Structure Messages for Real Impact
Design and messaging go hand in hand. Every message needs to do three things:
- Grab attention – Be bold, clear, and relevant.
- Give direction – Tell people exactly what to do next.
- Motivate – Show why it matters. Make the benefit personal and immediate.
No fluff. Just meaningful, well-timed communication.
6. Test It in the Real World
It’s one thing for someone to want to make a change. It’s another thing entirely for them to follow through. That gap is where great design plays a crucial role.
To truly shift behaviour, we have to go beyond just inspiring people, we need to support action. That means testing designs in real-world environments. Does it work on a busy commute? In a cluttered inbox? At 7am before the first, critical coffee of the day? We make sure our solutions fit naturally into people’s routines and their realities.
We also help people picture success and prepare for what might get in the way. That could mean prompting them to visualise the outcome they want, identify what could trip them up, and make a simple, clear plan for moving forward. It’s about helping them feel confident and capable, not overwhelmed.
By making the path to action feel practical, personal, and doable, we give people the tools they need to actually make the change they’re aiming for – not just make them think about it.
The Bottom Line?
Design is more than decoration. It’s behaviour change in action.
When we understand how people tick and we design with that in mind, we create communications that don’t just look good, but work brilliantly. That’s what drives results and what makes changes truly stick.
And that’s why design psychology isn’t just a nice-to-have – it’s integral to effective design.
Want to shape smarter design? Let’s chat – we’d love to help you make it happen.
