michelle madhok analyzes retail and marketing trends and knows these tactics all too well. >> these storesre set up to set off your brain in the pleasure center. they are hitting something in our human behavior that gets you to want to buy. we call it you are buying yourself happy. >> i'm in love with this but it is an extra small. >> there's lights music, smells good. it is immersing yourself in the feel-good experience. >> this is at h and m. you can see they are using the pricing technique to draw you in. instead of saying $10, it is $9.95 which makes it seem cheaper than it actually is. uniqlo is their fashion. they are good at limited edition. these are limited edition outfits they are doing with artists right now. andy warhol, keith herring. this is something fashion does to skraet a scarcity and mediascy to buy something. >> reporter: alex says learning the science behind her shopping habits won't deter her from getting that fashion fix. for "nightline," i'm mara schiavocampo in new york. >>> and next from snoop dogg to scooby-doo. whether you are a presidential hopeful or a sing er