I decided for health reasons I was definitely getting the haricots verts (fancy french for green beans). Then moments later when it was my turn to name 5 ingredients to go into my salad and was rushed by the salad-tosser-guy i just rattled off avocado, corn, alfalfa, artichokes, and tomatoes. After I got back to my desk and started eating, I noticed I had no green beans. I realized I had gone with "my usual" or what was familiar and safe.
So, in marketing, even if the marketing were so successful to have gotten a product in my consideration set and I had already decided to buy it, even then at the moment of purchase some other distractions may come into play that ultimately defeats the intended purchase.
How does marketing impact the moment of purchase and make one product "win" over another?