[grkvlt]

> no outside-of-store advertising plays a part here and in-store advertisement I typically ignore

Having read about the psychology of these things, I suspect you are more influenced than you would like. Even simple stuff like putting a more expensive product at the right height, and arranged in pleasing rows of identical objects, while the cheaper products are lower or higher (so difficult to get to) and in smaller quantities (so less of the pleasing identical objects effect) etc.

There are books on supermarket psychology, and I recall a good BBC documentary also, but can't think of any names right now, sorry.