Neuro Packaging test for the most Sustainable and Attractive Packaging

Tom van Bommel

Eindverantwoordelijke voor dit onderzoek
Main Question

What is the sustainability and volume perception of a cardboard versus plastic packaging?

At Unravel Research we love it: sweet peppers as a snack. We could therefore not be happier when Vitapep approached us for a packaging study. The well-known mini sweet pepper grower was curious about the effects of packaging material on the sustainability perception of the consumer.

In their efforts to pack their sweet peppers in a more environmentally friendly way, Vitapep is considering introducing cardboard packaging to replace their current plastic buckets. To make the switch to cardboard as successful as possible, the brand wants to map two things:

  • Is the cardboard packaging indeed associated with sustainability?
  • How does the cardboard packaging affect the volume perception or - freely translated - the feeling of 'value for money'?

Implicit Association Testing (IAT) on sustainability perception

Vitapep wanted to do more than just ask potential buyers to what extent they associate plastic and cardboard with sustainability. This form of traditional research often leads to distorted insights, arising from social desirability on the one hand and the major role of the unconscious regarding our associations on the other.

Unravel therefore turned to the Implicit Association Test (IAT) developed at Harvard. This method is able to quantify unconscious associations on the basis of processing speed in the brain. For example, the more strongly two thoughts are associated (a packaging photo + "Sustainable"), the faster the brain can process these concepts simultaneously.

Packaging Research Toolbox

How sustainable is cardboard for the brain

In this study, we tested a cardboard packaging versus three plastic variants:

  • A regular plastic bucket
  • A plastic bucket with the imprint “100% recycled plastic”
  • A plastic bag (flowpack in jargon)

The IAT showed that the cardboard buckets are indeed perceived as considerably more sustainable than the plastic variants. A plastic bag is slightly less sustainable, but is still considered more sustainable than a plastic bucket.

Interestingly, recycled plastic is considered less sustainable than a bucket without this label.

Although rationally counterintuitive, this is a well-known phenomenon in consumer psychological literature: when you emphasize that a negative point is not present or to a lesser extent, the consumer is more aware of the existence of this negative property. In this way, a boomerang effect occurs, which means that consumers consider packaging to be even less environmentally friendly.

Does the customer get value for money?

Each type of packaging differed greatly in shape. From the tall and narrow plastic buckets to the low and wide cardboard boxes. This brings up the challenge of volume perception; with which package does the customers feel like they get the most value for money?

To find out, Unravel conducted an estimation experiment. Three groups of 75 respondents each were presented with one type of packaging within a supermarket context, asking "How many grams of Vitapep do you think this package contains?". Because each group estimated a single package, there was no undesirable influence of multiple types of packaging on each other.

Interestingly, the volume is underestimated with the low wide cardboard packaging, while they are underestimated with the tall narrow plastic buckets. This is a well-known phenomenon in perception psychology: height overrules width. High packaging seem to be larger in volume. This research sublimely confirms that: people overestimate both plastic buckets and underestimate the cardboard packaging.


In explicit questioning, consumers indicate that a label with "recycled plastic" indicates to them that this packaging is sustainable. However, our unconscious associations show something completely different. We therefore know that consumers who care about sustainability, do not include this label in their consideration.

A super valuable insight for Vitapep that gives clear recommendations for even better (and sustainable) packaging.

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