This is lesson fourteen. This is towards one of our missions. Education. You’ll learn everything about marketing — from the basics to the most advanced strategies — for free, thanks to VellumWorks.
Have you ever wondered why people say they’ll donate or pay for your product… but don’t?
That frustrating gap between intention and action is exactly what the Theory of Planned Behaviour helps explain.
Developed by psychologist Icek Ajzen, it’s one of the most influential models in modern marketing and behavioural science.
It helps us understand why people behave the way they do, and more importantly, how to influence that behaviour ethically.
What is the Theory of Planned Behaviour?
The Theory of Planned Behaviour (TPB) is a psychological model developed by Icek Ajzen that explains why people decide to perform (or not perform) a certain behaviour.
At its core, the theory says that a person’s intention, their motivation or plan to act, is the strongest predictor of whether they’ll actually do something.
What is the core idea?
Human behaviour is guided by three key factors:
Attitude → What they believe about the behaviour.
Subjective Norms → What others expect them to do.
Perceived Behavioural Control → How easy or possible they think it is to act.
Together, these shape a person’s intention, which is the biggest predictor of whether they’ll actually take action.
Attitude: “Is this worth it?”
Attitude is how someone feels about the behaviour itself.
Do they see it as good, useful, or worth their time?
For example, if donors believe your charity truly makes an impact, they’ll feel positively about giving.
But if they’re unsure where the money goes, their attitude weakens — and so does their intent.
How to build positive attitudes:
Show tangible results (“£10 = 2 days of meals”)
Share real stories of impact
Use emotion and proof, not pressure
Subjective Norms: “What do people like me do?”
Humans are social creatures. We look to others: friends, influencers, communities, to decide what’s normal or admirable.
In marketing, these “social norms” are powerful.
When people see others supporting your cause, they feel encouraged to do the same.
How to use social proof effectively:
Show how many others have joined or donated
Highlight community challenges or team goals
Use testimonials and local ambassadors
Here is an example: “You’ll join 2,500 others who’ve already helped fund clean water projects this month.”
Perceived Behavioural Control: “Can I actually do this?”
Even if someone wants to act, they might not if it feels too hard.
Maybe your form is too long, your message too vague, or they feel their small donation won’t make a difference.
That’s where perceived control matters: how easy it feels to take action.
How to increase perceived control:
Simplify every step (1-click donate, prefilled forms, instant confirmation)
Offer flexible options (monthly vs one-time, small vs large gifts)
Reinforce the impact of any contribution
When people believe they can act, they usually will.
How These Work Together
The Theory of Planned Behaviour shows that decisions don’t happen randomly. They’re shaped by beliefs, norms, and control.
When attitudes are positive, social norms are supportive, and perceived control is high, the intention to act becomes powerful and often turns into real behaviour.
It’s the foundation of ethical influence: helping people take action they already believe in.
10-Minute Exercise: Audit Your Campaign with TPB
Take one campaign: maybe a donation page, newsletter, or volunteer drive and ask:
Does it make people feel good about the action (attitude)?
Does it show others doing the same (social norm)?
Does it make it easy and possible to act (control)?
Wherever one of these is weak, intention and results will drop.
Why is this important to know?
The EKB Model reminds us that donors and supporters aren’t ATMs. They’re people with needs, values, and emotions.
When you respect that process and guide them thoughtfully through it, you build something stronger than a one-time donation: a relationship.
At VellumWorks, we believe knowledge should be free. That’s why this series will guide you, step by step, through everything from the basics to the most advanced strategies in marketing: no jargon, no gatekeeping, just education that empowers.
