Frogs, fried chicken, fags, F1 and find the lady!

4 September 2023

There’s an old consumer psychology story about boiling frogs that got me thinking about why I’m absolutely sure there are less crisps in my packet.

Allow me to demonstrate:

You will need:

Frogs (around 20)

A large saucepan


A net (the type you go rock pooling with)

Half fill a pan with water, bringing it to a medium heat. When the water is very warm, pour the frogs in. The frogs will immediately jump out. Use the net to catch them. Put them to one side.

Empty the pan and allow to cool. Once cool, half fill with cold water and add frogs. Place pan on a low heat. The water will slowly go from cold to boiling hot. The frogs will all die, as they will not respond to the small incremental changes in temperature until it is too late.

Obviously this is just an allegorical representation of incremental change. No frogs died. But this story has been retold many, many times in order to illustrate many different points. Some good. Some bad. The gradual process of falling in love, or the gradual erosion of civil rights. Or indeed both, depending upon where you are in your personal life!

A really good example of how this affects the life of my family, can be seen in the giving out of Christmas and Birthday presents by my Mother. She has gradually, and incrementally, moved from wrapping presents, to simply handing out the unwrapped present in the bag the store placed it in.

Just the other day I had to take an unwrapped box, with a doll inside, around to my cousin’s, as it was her daughter’s birthday. I asked Mum to wrap it, so she scurried off and came back with the box shoved in a bag that said Happy Christmas (the box is still unwrapped). Again I left saying nothing. The water gets a little warmer. I’m now convinced that I’m going to come downstairs one morning to find a load of flour, eggs, butter, sugar and milk pushed through my letterbox – with a note from my Mum that cheerfully reads “Enjoy the cake!”

Happy Birthday

Happy Birthday

So how do brands manipulate us like the pot of frogs we are – and why don’t we do anything about it?

Well the answer lies in something known as ‘The Just Noticeable Difference

According to Weber’s Law of Just Noticeable Differences the Difference Threshold or “Just Noticeable Difference” (jnd) is the minimum amount by which stimulus intensity must be changed in order to produce a noticeable variation in sensory experience.

There’s even a little experiment you can do here

For those of you who like this sort of thing, here’s what the jnd looks like as an equation:

Don't panic

Don’t panic

It can be measured in physical units, we have where “I” is the original intensity of stimulation, “WebersLaw2” is the addition to it required for the difference to be perceived (the jnd), and “k” is a constant.

For those of you who prefer this sort of thing

Come on in, the water's lovely

Come on in, the water’s lovely

Let’s get back to the frogs. And more importantly the small increments of change that cause them ultimately to croak (sorry couldn’t resist it).

So the jnd has mass implications across all areas of our lives, but this Blog is concerned with the really interesting things that happen in the consumer world when we stay under the jnd. Obviously there is the other side of jnd. The side that draws our attention to product enhancements and price cuts, but I think the more interesting things lie in the covert way that things chage in front of our eyes, without us noticing. Because that’s exactly what ‘they’ want – us not to notice.

Operating under the jnd to cut product range and save money is something that happens on a daily basis. In fact it happens so often, there’s a name for it. Retailers call it ‘Efficient Assortment’. And psychologists like Broniarczyk et al (1998) asked themselves why is all the choice disappearing from the shops? Susan M Broniarczyk et al (1998) looked at what retailers call ‘Efficient Assortment’. Having realised that retailers need to reduce their shopkeeping units (sku’s) in order to remain competitive, retailers were concerned that adopting efficient assortment would lower consumer assortment perceptions and that would decrease the likelihood of store choice. Utilising two heuristic clues, Broniarczyk and her colleagues examined how consumers form assortment perceptions in the face of sku reduction, with particular emphasis on the availability of a favourite item, as well as the amount of general store space devoted to the category.

The study showed that retailers were able to make substantial reductions in sku’s carried without negatively effecting assortment perceptions and store choice, as long as low-preference items are eliminated and category space is held constant. In other words, as long as product choice is altered below the jnd, then our perceptions let it go unnoticed.

So, if we don’t notice those subtle changes in product choice differences, what else are we missing? Well how about the amount of products we’re being sold? Because our inability to spot decreases in the amount of product we’re being sold, as long as the reduction stays below our jnd is a great way of getting more profits out of us customers, without the pain of trying to increase the price we pay. It’s a strategy called ‘Package-Pricing’. And it’s happening everywhere.

Spot the difference

Spot the difference

Ok so in our supermarket from hell, we’ve had the choice subtly reduced, but as it remained just under our jnd, we’re ok about the whole thing. What about the products themselves?

For years, I’ve been telling everyone that would listen that my crisp packet has not only been inflated to the point of popping, but it also contains less crisps. No one ever listened, but it turns out I was right!

It drives me mad. I feel ripped off and lied to. And it turns out that I’m not alone. Research by lobby group Which? found 58 per cent of us would rather pay more than have goods downsized.

But just like the frogs, we let the these things slip by unnoticed as they don’t quite reach the jnd mark.

Other interesting uses of the jnd are in updates of trademarks and logos.

You only really notice when you see the line up

You only really notice when you see the line up

There’s so much equity in a brand that companies are rightly nervous regarding playing around with the brand too much. So they do it over a long period of time, hoping to stay as near to being under the jnd as possible. Or at least not too far above it.

It’s a good way of subtly moving a brand like Kentucky Fried Chicken away from the word ‘fried’. Done incrementally we can see how it moved KFC from a fried chicken association to just chicken.

We no longer say the F-Word

We no longer say the F-Word

One of the more interesting uses of this concept over recent years has been cigarette advertising in and around Formula 1 racing. Ferrari was traditionally always paired with Marlboro Cigarettes. In fact the brands were synonymous with one another on the F1 circuit. So when cigarette advertising was banned, Marlboro relied upon the strong association of the brand (mainly through the colour red) and took the bold step of introducing symbols instead of letters, that still delivered the cigarette brand.

Now you see them

Now you see them

Now you don't - but actually you still do!

Now you don’t – but actually you still do!

With all of the associations, proximities and partnership associations with the two brands, the symbolic representation of Marlboro kept them in full focus on the F1 circuit. Now that Marlboro no longer sponsor F1, I’m not sure that Santander should have been quite so fast to leap in. For me, and it’s subjective, they don’t make it over my jnd threshold enough to break my association with Ferrari and Marlboro.

Possibly a bit too close to the previous association

Possibly a bit too close to the previous association

Why is it that whenever I see a poster for Santander Online banking I want a cigarette?



Other Consumer Psychology Articles:

Cats, Google and the pleasure to be found in a worldwide computer meltdown

Our love of luxury brands is genetic! Take it from the Consumer Psychologists.





SM Broniarczyk, WD Hoyer, L McAlister – Journal of Marketing Research, 1998 – JSTOR
Consumers’ perceptions of the assortment offered in a grocery category: the impact of item reduction

Consumers Prefer to Get More Rather than Pay Less – Because They’re Bad at Math

Ernst Heinrich Weber (1795–1878)–price-remains-same.html