An alpha consumer is someone that plays a key role in connecting with the concept behind a product, then adopting that product, and finally validating it for the rest of society.
They feel the first vibrations of the explosion and transmit them to the rest of the culture.
The women who flocked to the touchy-feely movie The Bridges of Madison County followed their daughters to Titanic.
The college music fans who discovered Hootie & the Blowfish were different from the VH1 audience that made them a national phenomenon.
The first Jeep buyers were a far cry from the soccer moms now cruising about in their nine-seater Suburbans.