How Behavioural Science Reveals How We Really Think, Decide and Act
By Let’s Think
Behavioural Science AI combines behavioural science methods with GenAI and advanced analytics to surface, evolve, and amplify expert knowledge. It’s a prized asset rarely captured by traditional systems. In Part 1 of our explainer series, we unpack what behavioural science really is—and what it’s not.
Image copyright: Becky Stevens: “Memory Leak” by CREST Research, CC BY-NC-SA 2.0As AI rapidly transforms how we work and live, there's growing recognition of something essential: that technology is only as useful as our understanding of the humans using it. Behavioural science offers a powerful lens for this understanding, but it’s often misunderstood.
For many, it’s associated with nudging—those subtle design tweaks that steer people toward safer, healthier (or more profitable) decisions. Think opt-out organ donation, default pension schemes, or perfectly-timed app notifications.
The popularity of “nudges” grew from the work of Daniel Kahneman and Amos Tversky, who famously revealed how we’re prone to cognitive biases—mental shortcuts that can sometimes lead us astray. Their research helped launch behavioural economics, and it has become shorthand for a diverse field deeply rooted in scientific rigour.
But behavioural science is much broader than that.
So, what is behavioural science?
Behavioural science is the study of human behaviour: how people think, decide, communicate, and act, especially in social and systemic contexts. It’s a multidisciplinary field dedicated to understanding not just what we do, but what, where, when, why and how we do things. It blends insights from both natural and social sciences, such as:
Psychology: how we perceive, learn, remember, think and feel
Neuroscience: what’s happening in the brain
Sociology, anthropology & political science: how we interact within groups, institutions and systems
Behavioural scientists use diverse methods: from self-report questionnaires and experiments, to brain imaging and ethnographic observation, not just to describe behaviour, but to understand why it happens, and how it can be supported and improved.
A common misconception, rooted in the “nudge theory”, is that behavioural science focuses on how humans are flawed, irrational, or easy to trick.
In reality, many of these so-called flaws are adaptations that work incredibly well in real life, especially when decisions are fast, high-stakes, and complex.
How experts actually think
Other fields of cognitive science look not at average consumers in controlled experiments, but at real experts making tough decisions in real environments—like emergency responders, pilots and military leaders.
Initially developed by cognitive psychologist Gary Klein, this research shows that experts often don’t compare options rationally at all. Instead, they:
Rapidly assess the situation by matching it to past experience
Use intuition to recognise patterns and simulate likely outcomes
Make fast, high-quality decisions under pressure
This explains why experience matters—not because it makes people smarter, but because it shapes their internal understanding of how things work.
Enter tacit knowledge: The hidden engine of expertise
So how do experts actually know what to do, if they’re not consciously reasoning through every step? The answer lies in different types of knowledge:
Explicit knowledge: formal, written information (books, policies, training)
Implicit knowledge: what you know from experience, but can explain if asked
Tacit knowledge: deep, intuitive understanding that’s hard to articulate. It just feels right
Tacit knowledge is elusive—difficult to elicit and measure, and often invisible in traditional systems. Yet most people instinctively know it exists and that it’s critical to expert decision making. For example, a trauma surgeon may instantly recognise signs of internal bleeding and act without waiting for a scan, or a fire commander may detect subtle cues of a structural collapse and change strategy on the spot. These are not guesses—they’re rapid, experience-based decisions powered by pattern recognition and mental simulation. This is tacit knowledge in action.
“I help people and organisations navigate human complexity, not with guesswork, but with insight. Technology can be a delivery mechanism for that process, and behavioural science principles can be used to design the technology” – Anna Leslie, Chief Scientific Officer and Co-founder, Let’s Think
Why this matters in knowledge work
While behavioural science insights can be used to influence others, its greater power lies in helping organisations understand and support how people actually work, especially in complex fields with frequent high stakes decisions such as law, financial services, law enforcement, and medicine.
We can use Behavioural Science to:
Understand expert decision making
Support judgement under uncertainty
Design tools and systems that work with, not against, human cognition
Make tacit knowledge shareable and visible
At Let’s Think, we’re applying behavioural science principles to build tools that help people think brilliantly—because when they do, they make better decisions, solve harder problems, and create real impact. That’s the kind of thinking the world needs more of.
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If you are new to decision making research, a helpful jargon-busting overview can be found in this A–Z of decision-making from CREST, which outlines key terms and frameworks used across the field.
