The more effort something is, the more you value the result.

What is the commitment personal investment bias? 

The commitment – personal investment bias is the theory that the more involved people are in creating something, the better they feel about the end product. 

Meaning self-constructed products are valued more by the person who made it because of the effort it took.

The evidence it works

In the 50’s instant cake mix was invented, but it ran into a problem. People were used to baking and proud of what they could create. So, they were less likely to engage with the new product.

Manufacturers had a clever idea to solve the problem. They realised if they put ‘add an egg’ in the recipe customers still felt like they were baking the cake themselves and so sold more of the product (Shapiro 2004).

We’re naturally inclined to think more effort equals less sales. But in reality, whether it’s a cake mix or a flat pack bed, we feel more personal investment in the end product if we’ve had a hand in creating it.

Where it fits in our behavioural model – The ‘means’ METRIC

The three core principles of our Behavioural Model is that every behaviour has to have a motivation, trigger and the means.

The means are the resources to get what you want. This isn’t just money – choosing and buying also costs time and effort, thought and worry.

In theory, the means depend on what’s in short supply. So if we’re short of time, we’ll spend money. If we don’t want to take a risk, we’ll invest more thought. If everyone else is doing one thing, we’d rather join the queue and spend time, than feel like the odd one out.

But our judgement of these things is often flawed. For example, we can only judge numbers in comparison with other numbers and we’re inclined to not waste energy, so the easier something seems the more likely we are to choose it (like joining the queue). Which forms the basis of our Behavioural Model.

The means model is split into six different sections: Money, Effort, Time, Risk, Individuality, and Conscious thought. Which handily spells METRIC.

Commitment – personal investment fits into the effort category. If you’ve put effort into something, it’s more likely to hold value. 

For example getting rid of a jumper you’ve knitted over a jumper you’ve bought. Even though the bought jumper is higher quality, you’re more likely to keep the one you made.



IKEA use the commitment: personal investment bias extremely well, selling furniture we build ourselves so we feel great about the end product. Plus, we know it’s good value because the effort hasn’t gone into it yet. Sometimes referred to as the ‘Ikea Effect’

Sample IKEA Instructions


Again, with LEGO we have fun doing it, even though it’s more effort, because we’re committed to the end result. 

Add in past experiences of how rewarding it is and we’re personally invested before we even begin.

Commitment personal investment lego

How we can help you

We’re a creative agency that uses behavioural science to make marketing more effective.

We deliver everything from insights and strategy development for brand building or big ideas right down to tactical campaigns and execution.

If you’d like to find out more about how we can help you to apply behavioural science creatively then please get in touch.

By Ellen Jackson

Creative Copywriter