Yup, psych has been looking at this intently for a while - I think cognitive has been doing work looking into this.

There was an article on this a while back on HN as well - why walmart knew someones daughter was pregnant before her dad did. (forbes, after taking it from wired iirc)

Its based on the fact that peoples habits (in regards to shopping) are ingrained, and that there are only a few times in life when those habits are open to change.

Thats when there is a major change in their life - like a new job, baby, marriage and so on.

Dan O Reily (from arming the Donkeys) also had an old pod cast on this.