The human being is curious by nature, when we meet our neighbor at the store with a shopping bag filled, we would like to know what he bought (do not tell me that it has never crossed you the mind!).
Besides curiosity, it can sometimes give us ideas ...
Another novelty this week!
We know that consumers trust consumers much more than merchants themselves!
So if a merchant tells you, "this product is the best", few of you will be convinced.
On the other hand if another customer tells you "I tested it, it's really the best!", There however the doubt will be raised and there will be a phenomenal queue at the cash register!
This is called social proof. This principle has been applied since the beginning of time and it is very human :-)