Simplicity in behavioural science: reflections on EAST and beyond
How do the tools we champion shape not only our interventions, but the craft of our field and the expertise we value?
Michael Hallsworth recently published a thoughtful reflection on the continued relevance of the EAST framework, arguing that simplicity offers resilience in a complex world. To illustrate his point, he reaches for a memorable metaphor: EAST, he suggests, is like a BIC pen - a simple, reliable tool whose enduring value lies in its universal, accessible design.
It’s an elegant image that invites reflection. How do the tools we champion shape not just our interventions, but the craft of our field and the expertise we value? Simplifying a tool doesn’t just change its design — it changes what people think they know, and how far they think they can go without help.
This piece offers a collegial response, exploring where simplicity strengthens behavioural practice, where it risks limiting it, and why the ways we talk about tools quietly shape both how the field is perceived and how it evolves. I shared an early draft with Michael Hallsworth as part of that dialogue, and refined several sections after thoughtful exchanges and clarifications where we also discovered that, despite different working contexts, we are largely in agreement on the fundamentals.
Simplicity as resilience, or simplification as flattening?
Hallsworth argues that simplicity offers resilience. Frameworks like EAST, he suggests, help people navigate complexity without becoming paralysed, stripping interventions down to core principles that remain robust across contexts and under pressure.
There’s real merit here: simplicity can create traction where complexity overwhelms, but simplicity can also flatten. Relying too heavily on broad heuristics risks missing the nuances, trade-offs, and contextual details that make behavioural interventions effective and ethical.
To make this concept more concrete, let's look at dog training as an analogy. Positive reinforcement, at its simplest, is an invaluable tool for everyday dog owners. But without a deeper understanding of timing, motivation, and environmental cues, it’s often applied poorly and it can even be applied coercively. Owners may conclude “positive reinforcement doesn’t work” and abandon it in frustration, sometimes switching to punitive methods. Here, simplicity doesn’t just fail but instead it can backfires dramatically.
Cognitive biases can quietly reinforce this dynamic. For example, confirmation bias leads people to remember when simple approaches seem to work and forget when they don’t. Over time, this can entrench the myth that simplicity is always sufficient, even in domains where more careful diagnosis and adaptation are needed.
The challenge, then, is not to abandon simplicity but to know where its limits lie and how to help practitioners recognise when simplicity begins to obscure, rather than clarify, the work at hand.
Popularity as a proxy for value, or as institutional inertia?
Hallsworth suggests that one way to judge frameworks is by their use: if a tool like EAST is widely adopted, that popularity can signal practical value. Simplicity, in this view, is not just an aesthetic virtue but a functional one - making behavioural science tools more likely to be applied, and therefore more likely to improve outcomes on the ground.
There’s intuitive appeal to this claim. After all, tools that sit unused on the shelf are of little help to practitioners under pressure and Hallsworth is clear that popularity alone does not make a framework adequate or universally fit for purpose. His point, rather, is to push back against the assumption that more sophisticated tools automatically yield better results and that tendency that can shape discourse in the field.
More broadly, it is worth reflecting on how popularity shapes practice. Frameworks can become widespread for many reasons, not all of which reflect their fitness for purpose. Availability, institutional inertia, marketing, mandates, and convenience can all drive uptake. A widely used tool may be useful, or it may simply be the easiest to reach for.
A useful comparison comes from medicine. Basic first aid is widely taught and used, often with life-saving consequences. Its popularity reflects its accessibility and the fact that it gives people practical means to respond in emergencies. But no one suggests that first aid can substitute for professional care. We don’t conclude that because basic first aid is widely taught, we no longer need paramedics, doctors, or surgeons. Popularity reflects reach and necessity, not sufficiency or sophistication.
The same caution applies in behavioural science. Just because EAST is widely used does not mean it is the best tool for every problem, or that it can replace more specialised frameworks. Here, availability bias can creep in: what is familiar and easy to remember tends to crowd out less visible or more complex tools, even when those tools are better suited to the challenge at hand.
The key, then, is not to dismiss simple tools because they are popular, nor to equate popularity with universal adequacy. As with first aid, we need to be clear about where simple tools are enough and where they are only the first line of response in a much larger system of expertise.
Complexity, fragmentation, and the misreading of frameworks
Hallsworth raises an important concern about complexity. He argues that adding more sophisticated frameworks like the Behaviour Change Wheel (BCW), COM-B, or the Theoretical Domains Framework (TDF) risks overwhelming practitioners and fragmenting the field. From this perspective, what looks like progress toward precision can instead produce confusion, duplication, and diminished practical impact.
There’s validity in this worry. The field has indeed seen an explosion of models and taxonomies, not all of which integrate well or achieve broad uptake, but here Hallsworth makes a move that needs more careful unpacking. Frameworks like COM-B and TDF are fundamentally different from EAST: they are not simple behaviour change prompts but diagnostic tools, intended to help experts understand complex behavioural problems and develop tailored interventions. Comparing them as if they compete in the same space risks collapsing distinct purposes and audiences into a single continuum of “more or less complex.”
Car maintenance offers a helpful analogy: many people know how do important simple tasks such as to check the oil or change a tire but when a car develops a complex fault, no one sensibly argues that a user manual or YouTube tutorial is enough. We turn to trained mechanics who work with diagnostic tools that, by nature, are more sophisticated.
In behavioural science, frameworks like COM-B and TDF play that diagnostic role. They exist not to replace simple tools but to guide deeper analysis when the problem demands it. The risk of dismissing them as “too complicated” is not just a category error - it may actually reinforce the fragmentation Hallsworth worries about, by pushing practitioners away from integrated approaches that could bring coherence to the field. Recognising when complexity is necessary, and when simplicity is enough, is part of the discipline’s craft and its responsibility.
Satisficing practitioners - but which practitioners?
Hallsworth makes a thoughtful point about the reality of practice: many practitioners are muddling through, making the best decisions they can with limited time, knowledge, or resources. From this angle, simple tools like EAST are not just helpful - they are humane, lowering cognitive load and offering something workable in the real world.
This raises a crucial distinction: who are we designing these tools for? It’s one thing to provide simple frameworks to frontline workers, public servants, or volunteers who need to make progress without becoming paralysed by technical detail. It’s another to suggest the same tools suffice for consultants, policy designers, or leaders who position themselves as behavioural experts. Without recognising this difference, we risk echoing dynamics seen in fields like UX, where the language of expertise has spread faster than the depth behind it.
Here, overconfidence and the illusion of explanatory depth come into play. Familiarity with a simple framework can give a false sense of mastery, masking how much deeper expertise is needed. Without clear distinctions between audiences, we risk misuse and an inadvertent devaluing of professional expertise.
Expert judgment, phronesis, and the limits of simplicity
Hallsworth’s final point turns toward the idea of practical wisdom. He suggests that expert judgment (what Aristotle called phronesis) allows skilled practitioners to use simple tools in sophisticated ways. In this view, simplicity is not inherently limiting, because good practitioners know how to apply it judiciously, adapting to context and recognising when a tool needs to be set aside.
There’s truth in this, but also a limitation. Expert improvisation depends on something that doesn’t “travel” with the tool: the expertise of the user. A doctor may use a checklist as a starting point, but their ability to interpret symptoms and order tests goes far beyond it. A mechanic may safely override a manual’s recommendation, but when an amateur tries the same, it often ends badly. What allows experts to use simplicity well is precisely what non-experts lack.
Even among professionals, biases can quietly reinforce overreliance on simple tools. People tend to notice when simple approaches succeed and overlook when they fall short. At the organisational level, shared defaults can spread responsibility so thinly that no one checks whether the right expertise is being applied.
Context matters: public sector realities and professional dilution
One of the most revealing aspects of discussing this piece with Michael was realising how much our different working environments shape what we notice as dominant risks. His experience, shaped by public policy work, often involves contexts where limited resources and high pressure make it pragmatic (even essential) to empower non-experts to apply behavioural insights, however imperfectly. In that setting, simple tools help spread responsibility, ease pressure on specialists, and raise the baseline of practice across large systems. There is often a push toward greater sophistication, and part of Michael’s aim has been to push back gently against the assumption that more complexity always produces better results.
My experience in the private sector, by contrast, frequently exposes the opposite dynamic. Many organisations have no dedicated behavioural expert to guide how tools like EAST are used. Instead, people often encounter behavioural ideas through popular books or articles and begin applying them enthusiastically across a wide range of challenges. This can lead to a false sense of mastery - a dynamic I’ve seen echoed in fields like UX, where the language of human-centred design has become familiar even as true expertise remains hard-won.
Surfacing this divergence matters because it highlights that the conversation about simplicity and sophistication plays out differently depending on institutional context, practitioner pressures, and the expertise available. The challenge is not to pit simplicity against sophistication, but to recognise where each belongs and to stay aware of how context, audience, and organisational setting shape the use of tools and the value placed on expertise. For me, the deeper question is: how do we equip non-specialists to recognise when they are stepping beyond their expertise, especially when the nature of our work makes those limits hard to see?
Conclusion: simplicity with judgment, clarity with care
Simplicity has an important and legitimate place in behavioural science. Frameworks like EAST have played a crucial role in making behavioural insights accessible, actionable, and scalable, particularly in resource-constrained environments. They have raised the profile of the field and offered practitioners practical tools to experiment, learn, and improve outcomes.
But simplicity is not a universal solution strategy. It works best when paired with clarity about purpose, audience, and limits. Without that clarity, simplicity risks becoming a cover for overreach, a magnet for overconfidence, or a substitute for the very expertise the field depends on.
What’s at stake here is not just the elegance of our tools, but the craft of our practice - the ability to know when simplicity serves, and when it constrains. That judgment is not something we can embed in an acronym or a framework. It’s something we cultivate, teach, and protect.
As we reflect on how behavioural science continues to grow and mature, perhaps the real challenge is not to choose between simplicity and complexity, but to learn how to hold them together with care and to help others do the same.
Michael’s LinkedIn post for the discussion