Just Noticeable Difference

Is your Freddo getting smaller?

Have you ever sat down to enjoy your favourite snack only to realise that your Freddo Frog now looks disappointingly smaller? I know I certainty have and if you’re anything like me this lack of satisfaction might even cause you to walk straight past it next time it blatantly looks at you on the supermarket shelf.

Despite my frustration, unfortunately change is factor of life. Brands will continue to update their image, cut costs and up their prices in order to remain competitive in this fast paced world we live in.

So if change is inevitable, how do brand managers control and minimise adverse reactions?

The answer is just noticeable difference, JND is a scientific term that describes the minimal amount of change between two stimuli that a person can detect (Sarhan, 2017). It’s a marketer’s role to determine the relevant threshold for their products and in doing so they can discretely advantage themselves in the following ways:

  • Negative changes like price increase, size or quality reductions can be placed below the JND threshold, limiting their visibility to the public.
  • Positive changes like improvements to product packaging or price reductions are placed above the threshold, making them more apparent to consumers without being wastefully extravagant. (Schiffman, et al 2014)

Are you being taken advantage of?

While the just noticeable difference threshold varies from product to product, as a general rule Campbell and Diamond (1990) explain that all promotions should be large enough to be noticed but small enough to be accepted.

For example, picture yourself in a clothing store. Is a sign displaying 10% off likely to change your buying behaviour? My guess is not.  Now imagine the store next door has a 40% off sign, this is more likely to excite you because marketers have tactically positioned the sale amount above the JND threshold (Pah, 2007).

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Marketers need to be careful when taking this approach, as reaching too far above the threshold can damage a brand in the long run due to the notion of Webers law. Webers law states that the stronger the initial stimulus, the greater the additional intensity must be. (Monroe, 1973). This means stores who continuously boast large sales are forced to constantly increase the discount amount in order to receive the same attention as before.

Just noticeable difference in action

JND is a widely used technique that can be applied to any element of the marketing mix including price, promotion, packing and product modification. Sometimes marketers use it so well that you may not even realise you have been targeted.

Logo modifications 
Over the year’s countless brands like BP have used the JND concept to update their brand logo. Carefully making incremental changes to ensure the brand remains identifiable by consumers, preventing years of marketing campaigns going to waste. BP followed this approach until 2000, when they saw the need for a new fresh logo upgrade that unified its acquired and existing brand image (Schiffman, et al 2014).

It’s important to consider the types of relations consumers may build with a particular brand and its product attributes. For Coca Cola, packing has been a defining aspect, thus marketers need to be extra cautious when modifying its outlook. Whilst it would be dangerous to change its 100 year old contour-shape, a more acceptable approach saw Coke customise their labels with popular millennial names, sparking a growth in sales, without impacting their brand image.


Bhutani (2011) explains lesser known brands or me-too products also use JND. They generate imitations that resemble original brands to influence purchase decisions. For example Aldi’s version of Coco Pops.

Have you ever noticed your favourite brands doing this? Good or bad let me know your thoughts below.



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