Are you one of those intrepid shoppers who stood in line to pick up a door buster deal on Black Friday?

Or perhaps you're reading this with your finger hovering over the mouse waiting to scoop up those Cyber Monday bargains. 

While the holidays can leave us full of cheer, they can also leave our wallets a little light. 

A Martinez talks with Kit Yarrow, professor of psychology and marketing at Golden Gate University in San Francisco, to explain WHY we buy and HOW to avoid spending too much on the wrong things this festive season.