Blind testing is a way to consumer test products or packages whereby consumers are unaware of the underlying brand which they are evaluating. The idea is to focus on the intrinsic product characteristics, so that the direction for R&D product development can be clearly derived.
The opposite of blind testing would be branded testing. There is currently a debate in the technical consumer science community whether testing products in context, is more relevant and realistic than blind testing. Still, when testing branded basically the result is driven by the brand image and the product characteristics in combination. Only when running blind testing, the effect of the product characteristic can be measured. Therefore the combination of blind and branded testing is best.
Products can be blinded different ways: The brand has to be removed, or should not be visible. The shape, size, dimensions should be such that the brand is not recognized. Some products can easily be tested blind, by refilling them in neutral containers. This is true for most liquid products, as long as the characteristic product features are not changed through refilling and the hygienic requirements are ensured.
Others, most solid products, have brand names imprinted, or they are easily identified as a specific brand. This means they can hardly be blinded, or the end product is no longer the same as the one consumers can buy.
In case of doubt it is recommended to add a brand recognition question, offering a choice of five well known brands to consumers, asking "Which brand does the product you just tried best match with?"
When time and budget allows, it is recommended to combine blind and branded testing, to understand the intrinsic product effects on top of the brand effect.
Branded tests for products with a premium image result in better scores than blind tests, whereas branded tests of products expected to be private label or cheap will result in worse scores versus blind.